每日一词:raddled(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 31, 2019 is:

raddled • \RAD-uld\  • adjective

1 : being in a state of confusion : lacking composure

2 : broken-down, worn

Examples:

We were met at the door by a raddled old man who turned out to be the actor’s father, and who in his day had also been an estimable presence on the London stage.

“The real skill of Swan Song is the kaleidoscopic portrait it paints of its raddled hero. The narrative moves through time from Capote’s tawdry childhood and friendship with Harper Lee to his withered end in Fu Manchu pyjamas.” — Alex Preston, The Observer (London), 22 July 2018

Did you know?

The origin of raddled is unclear. Its participial form suggests verbal parentage, and indeed there is a verb raddle just a few decades older than raddled that seems a likely source. This raddle means “to mark or paint with raddle,” raddle here being red ocher, or sometimes other pigments, used for marking animals. Raddle eventually came to mean “to color highly with rouge,” the metaphor connecting the raddling of animal husbandry with immoderate makeup application: to be raddled thusly was not a compliment. The “confused” sense of raddled is often associated with the influence of alcohol or drugs. That connection is in keeping with the word’s earliest known use, from a 1694 translation of French writer Francois Rabelais: “A … fellow, continually raddled, and as drunk as a wheelbarrow.”


Lake桑

January 31, 2019 at 01:00PM

每日一词:proliferate(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 30, 2019 is:

proliferate • \pruh-LIF-uh-rayt\  • verb

1 : to grow or cause to grow by rapid production of new parts, cells, buds, or offspring

2 : to increase or cause to increase in number as if by proliferating : multiply

Examples:

Muskies in Lake St. Clair are a world-class presence because local folks 30 years ago got smart. They agreed on a catch-and-release ethic. Catch the muskie. Put it back into the water. And watch a species proliferate.” — Lynn Henning, The Detroit News, 26 December 2018

“The surge in the price of bitcoin, and of other cryptocurrencies, which proliferated amid a craze for initial coin offerings, prompted a commensurate explosion in the number of stories and conversations about this new kind of money….” — Nicholas Paumgarten, The New Yorker, 22 Oct. 2018

Did you know?

Proliferate is a back-formation of proliferation. That means that proliferation came first (we borrowed it from French in the 18th century) and was later shortened to form the verb proliferate. Ultimately these terms come from Latin. The French adjective prolifère (“reproducing freely”) comes from the Latin noun proles and the Latin combining form -fer. Proles means “offspring” or “descendants,” and -fer means “bearing.” Both of these Latin forms gave rise to numerous other English words. Prolific and proletarian ultimately come from proles; aquifer and words ending in -ferous have their roots in -fer.


Lake桑

January 30, 2019 at 01:00PM

每日一词:charisma(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 29, 2019 is:

charisma • \kuh-RIZ-muh\  • noun

1 : a personal magic of leadership arousing special popular loyalty or enthusiasm for a public figure (such as a political leader)

2 : a special magnetic charm or appeal

Examples:

The young singer had the kind of charisma that turns a performer into a star.

“Winner of seven Tony Awards including Best Musical, ‘Evita’ is the story of Eva Peron who used her charisma and charms to rise from her penniless origins to political power as the first lady of Argentina at the age of 27.” — Oscar Sales, The Press Journal (Vero Beach, Florida), 19 Dec. 2018

Did you know?

The Greek word charisma means “favor” or “gift.” It is derived from the verb charizesthai (“to favor”), which in turn comes from the noun charis, meaning “grace.” In English, charisma has been used in Christian contexts since the mid-1500s to refer to a gift or power bestowed upon an individual by the Holy Spirit for the good of the Church, a sense that is now very rare. The earliest nonreligious use of charisma that we know of occurred in a German text, a 1922 publication by sociologist Max Weber. The sense began appearing in English contexts shortly after Weber’s work was published.


Lake桑

January 29, 2019 at 01:00PM

每日一词:sleuth(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 28, 2019 is:

sleuth • \SLOOTH\  • verb

1 : to act as a detective : search for information

2 : to search for and discover

Examples:

“Farmer would go sleuthing in the archives of Arizona State University’s Center for Meteorite Studies to find evidence of an undiscovered landfall in Canada, and Ward could build a rig that trailed an 11-foot metal detector behind a combine, which is how they unearthed $1 million in pallasite fragments from several square miles of Alberta farmland.” — Joshuah Bearman and Allison Keeley, Wired, January 2019

“For more than five decades, Morse has sleuthed out long-lost family trees for a living. From his home base here in Haywood, Morse travels the world tracking down missing heirs.” — Becky Johnson, The Mountaineer (Haywood County, North Carolina), 20 Nov. 2018

Did you know?

“They were the footprints of a gigantic hound!” Those canine tracks in Arthur Conan Doyle’s The Hound of the Baskervilles set the great Sherlock Holmes sleuthing on the trail of a murderer. It was a case of art imitating etymology. When Middle English speakers first borrowed sleuth from Old Norse, the term referred to “the track of an animal or person.” In Scotland, sleuthhound referred to a bloodhound used to hunt game or track down fugitives from justice. In 19th-century U.S. English, sleuthhound became an epithet for a detective and was soon shortened to sleuth. From there, it was only a short leap to turning sleuth into a verb describing what a sleuth does.


Lake桑

January 28, 2019 at 01:00PM

又一个周一。

一周又开始了。加油工作!(由 IFTTT 发送)

Lake桑

January 28, 2019 at 07:00AM

每日一词:foray(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 27, 2019 is:

foray • \FOR-ay\  • noun

1 : a sudden or irregular invasion or attack for war or spoils : raid

2 : an initial and often tentative attempt to do something in a new or different field or area of activity

Examples:

“Although she debuted a line of jewelry last year, this is her first foray into creating her own makeup line.” — Hayley Schueneman, The New York Magazine, 28 Nov. 2018

“Edgardo Defortuna has been flying high for years, … erecting a string of ultra-luxury condo and hotel towers on his way to becoming one of Miami’s most prominent developers. He recently announced his first foray outside South Florida, unveiling a design for a trio of luxury towers in Paraguay.” — Andres Viglucci and Rene Rodriguez, The Miami Herald, 16 Dec. 2018

Did you know?

Foray comes from Middle English forrayen and probably traces back to an Anglo-French word that meant “raider” or “forager.” It’s related to the word forage, which commonly means “to wander in search of food (or forage).” Foray, in its earliest sense, referred to a raid for plunder. Relatively recently, foray began to take on a broader meaning. In a sense, foray still refers to a trip into a foreign territory. These days, though, looting and plundering needn’t be involved in a foray. When you take a foray, you dabble in an area, occupation, or pastime that’s new to you.


Lake桑

January 27, 2019 at 01:00PM

每日一词:doldrums(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 26, 2019 is:

doldrums • \DOHL-drumz\  • plural noun

1 : a spell of listlessness or despondency

2 often capitalized Doldrums : a part of the ocean near the equator abounding in calms, squalls, and light shifting winds

3 : a state or period of inactivity, stagnation, or slump

Examples:

“A vacation on a tropical island could be just the thing you need to fight against the winter doldrums,” said Christine as she handed me the resort’s brochure.

“At the time, the bourbon industry was in the process of emerging from a lengthy period of doldrums and rebranding itself as not just something old men drank.” — The Kentucky Standard, 21 Nov. 2018

Did you know?

Almost everyone gets the doldrums—a feeling of low spirits and lack of energy—every once in a while. The doldrums experienced by sailors, however, are usually of a different variety. In the early-19th century, the word once reserved for a feeling of despondency came to be applied to certain tropical regions of the ocean marked by the absence of strong winds. Sailing vessels, reliant on wind propulsion, struggled to make headway in these regions, leading to long, arduous journeys. The exact etymology of doldrums is not certain, though it is believed to be related to the Old English dol, meaning “foolish”—a history it shares with our adjective dull.


Lake桑

January 26, 2019 at 01:00PM

每日一词:myopic(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 25, 2019 is:

myopic • \mye-OH-pik\  • adjective

1 : affected by myopia : of, relating to, or exhibiting myopia : nearsighted

2 : lacking in foresight or discernment : narrow in perspective and without concern for broader implications

Examples:

“This is, on the whole, an encouraging finding. If children became myopic due to looking at objects too closely, then we’d be stuck with an unsolvable dilemma: choosing between teaching children to read and protecting their eyesight.” — Brian Palmer, Slate, 16 Oct. 2013

“But even the most myopic seer can foretell with near certainty that our traditional use of privately owned vehicles running on fossil fuels is going to be giving way to new mobility options, and soon.” — John Gallagher, The Detroit Free Press, 9 Dec. 2018

Did you know?

Myopia is a condition in which visual images come to a focus in front of the retina of the eye, resulting in defective vision of distant objects. Those with myopia can be referred to as “myopic” (or, less formally, “nearsighted”). Myopic has extended meanings, too. Someone myopic might have trouble seeing things from a different perspective or considering the future consequences before acting. Myopic and myopia have a lesser-known relative, myope, meaning “a myopic person.” All of these words ultimately derive from the Greek myōps, which comes from myein (meaning “to be closed”) and ōps (meaning “eye, face”).


Lake桑

January 25, 2019 at 01:00PM

又一个周五!


周五中午啦~ 吃完午饭,下午继续工作! (由 IFTTT 发送)

Lake桑

January 25, 2019 at 12:00PM

每日一词:adjudicate(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 24, 2019 is:

adjudicate • \uh-JOO-dih-kayt\  • verb

1 : to make an official decision about who is right in (a dispute) : to settle judicially

2 : to act as judge

Examples:

“… Nichols said in addition to the nine dogs brought to the shelter, it is housing 31 dogs that were confiscated in animal cruelty or neglect cases. She said the shelter has to board the dogs, feed them and care for them until the cases are adjudicated.” — Russ Coreyemp, The Times Daily (Florence, Alabama), 16 Dec. 2018

“To qualify as a couture house, which is an official designation like champagne, a brand must maintain an atelier of a certain number of artisans full time and produce a specific number of garments twice a year for a show. There are only a very few that can fulfill the requirements…. A lot have dropped out over the years …, and the governing organization that adjudicates this has relaxed some of its rules to admit younger, less resourced and guest designers….” — Vanessa Friedman, The New York Times, 17 Dec. 2018

Did you know?

Adjudicate is one of several terms that give testimony to the influence of jus, the Latin word for “law,” on our legal language. Adjudicate is from the Latin verb adjudicare, from judicare, meaning “to judge,” which, in turn, traces to the Latin noun judex, meaning “judge.” English has other judex words, such as judgment, judicial, judiciary, and prejudice. If we admit further evidence, we discover that the root of judex is jus. What’s the verdict? Latin “law” words frequently preside in English-speaking courtrooms. In addition to the judex words, jury, justice, injury, and perjury are all ultimately from Latin jus.


Lake桑

January 24, 2019 at 01:00PM

有论坛啦啊啊啊啊啊啊啊!

我们终于开了论坛。

准确的来说就我一个人。

链接:https://lakejason0.wixsite.com/forum

Lake桑

2019.1.23

每日一词:imbroglio(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 23, 2019 is:

imbroglio • \im-BROHL-yoh\  • noun

1 a : an acutely painful or embarrassing misunderstanding

b : a circumstance or action that offends propriety or established moral conceptions or disgraces those associated with it : scandal

c : a violently confused or bitterly complicated altercation : embroilment

d : an intricate or complicated situation (as in a drama or novel)

2 : a confused mass

Examples:

“He was close to scandal—GOP chairman during the Watergate years, vice president during the Iran-Contra imbroglio—yet was not tainted by it.” — David M. Shribman, The Boston Globe, 1 Dec. 2018

“The present imbroglio follows protracted struggles over the budget of the sheriff’s office, the fate of the 911 system, the county role in reducing blight and who should pay what for animal control.” — Rockford (Illinois) Register Star, 13 Dec. 2018

Did you know?

Imbroglio and embroilment are more than just synonyms; they’re also linked through etymology. Both descend from the Middle French verb embrouiller (which has the same meaning as embroil), from the prefix em-, meaning “thoroughly,” plus brouiller, meaning “to mix” or “to confuse.” (Brouiller is itself a descendant of an Old French word for “broth.”) Early in the 17th century, English speakers began using embroil, a direct adaptation of embrouiller, as well as the noun embroilment. Meanwhile, the Italians were using their own alteration of embrouiller: imbrogliare, meaning “to entangle.” In the mid-18th century, English speakers embraced the Italian noun imbroglio as well.


Lake桑

January 23, 2019 at 01:00PM

每日一词:cumulate(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 22, 2019 is:

cumulate • \KYOO-myuh-layt\  • verb

1 : to gather or pile in a heap

2 : to combine into one

3 : to build up by addition of new material

Examples:

“In the alternative, the company may provide greater input to minority shareholders by allowing shareholders to cumulate their votes and cast them all for one director.” — Gregory Monday, The Milwaukee Business Journal, 5 Mar. 2018

“The report … compares various income estimates and reaches a similar conclusion: Most Americans have realized small annual increases that ultimately cumulated into meaningful gains.” — Robert Samuelson, The Sun Journal (Lewiston, Maine), 12 Dec. 2018

Did you know?

Cumulate and its far more common relative accumulate both come from the Latin word cumulare, meaning “to heap up.” Cumulare, in turn, comes from cumulus, meaning “mass.” (Cumulus functions as an English word in its own right as well. It can mean “heap” or “accumulation,” or it can refer to a kind of dense puffy cloud with a flat base and rounded outlines.) Cumulate and accumulate overlap in meaning, but you’re likely to find cumulate mostly in technical contexts. The word’s related adjective, cumulative, however, is used more widely.


Lake桑

January 22, 2019 at 01:00PM

每日一词:substantive(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 21, 2019 is:

substantive • \SUB-stun-tiv\  • adjective

1 : having substance : involving matters of major or practical importance to all concerned

2 : considerable in amount or numbers : substantial

3 a : real rather than apparent : firm; also : permanent, enduring

b : belonging to the substance of a thing : essential

c : expressing existence

4 a : having the nature or function of a noun

b : relating to or having the character of a noun or pronominal term in logic

5 : creating and defining rights and duties

Examples:

“How many more carefully researched reports will need to be released before we finally act in a substantive way to protect our only home, planet Earth?” — Edwin Andrews, The New York Times, 14 Dec. 2018

“These are the moments—funny, yet substantive and cuttingly insightful—that will remain in the collective memory long after Ralph Breaks the Internet leaves cinemas and many of its meme jokes lose their relevance.” — Jim Vejvoda, IGN (ign.com), 20 Nov. 2018

Did you know?

Substantive was borrowed into Middle English from the Anglo-French adjective sustentif, meaning “having or expressing substance,” and can be traced back to the Latin verb substare, which literally means “to stand under.” Figuratively, the meaning of substare is best understood as “to stand firm” or “to hold out.” Since the 14th century, we have used substantive to speak of that which is of enough “substance” to stand alone, or be independent. By the 19th century, the word evolved related meanings, such as “enduring” and “essential.” It also shares some senses with substantial, such as “considerable in quantity.”


Lake桑

January 21, 2019 at 01:00PM

又一个周一。

一周又开始了。加油工作!(由 IFTTT 发送)

Lake桑

January 21, 2019 at 07:00AM

每日一词:wherewithal(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 20, 2019 is:

wherewithal • \WAIR-wih-thawl\  • noun

: means or resources for purchasing or doing something; specifically : financial resources : money

Examples:

If I had the wherewithal, I’d buy that empty lot next door and put in a garden.

“Typically, when a person makes more money and has more savings, they add credit such as signing up for a new card or taking on a car loan. That’s because they’re confident they have the financial wherewithal to pay back the debt.” — Janna Herron, USA Today, 5 Dec. 2018

Did you know?

Wherewithal has been with us in one form or another since the 16th century. It comes from our still-familiar word where, and withal, a Middle English combination of with and all, meaning “with.” Wherewithal has been used as a conjunction meaning “with or by means of which” and as a pronoun meaning “that with or by which.” These days, however, it is almost always used as a noun referring to the means or resources—especially financial resources—one has at one’s disposal.


Lake桑

January 20, 2019 at 01:00PM

每日一词:gargantuan(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 19, 2019 is:

gargantuan • \gahr-GAN-chuh-wuhn\  • adjective

: tremendous in size, volume, or degree : gigantic, colossal

Examples:

“In 1920, the town council of Chamonix … decided to change the municipality’s name to Chamonix-Mont-Blanc, thus forging an official link to the mountain … with a summit that soars 12,000 feet above the town center. The council’s goal was to prevent their Swiss neighbors from claiming the mountain’s glory, but there was really no need: It’s impossible when you’re in Chamonix to ignore the gargantuan, icy beauty that looms overhead.” — Paige McClanahan, The New York Times, 13 Dec. 2018

“Due to our gargantuan scope, Houston is a haven for live music. As the nation’s fourth largest city, we have become a destination for touring acts by default—it certainly isn’t because of our collective reputation as an audience….” — Matthew Keever, The Houston Press, 17 Dec. 2018

Did you know?

Gargantua is the name of a giant king in François Rabelais’s 16th-century satiric novel Gargantua, the second part of a five-volume series about the giant and his son Pantagruel. All of the details of Gargantua’s life befit a giant. He rides a colossal mare whose tail switches so violently that it fells the entire forest of Orleans. He has an enormous appetite: in one memorable incident, he inadvertently swallows five pilgrims while eating a salad. The scale of everything connected with Gargantua gave rise to the adjective gargantuan, which since William Shakespeare’s time has been used of anything of tremendous size or volume.


Lake桑

January 19, 2019 at 01:00PM

化学相关:化学方程式

目录:化学相关:开坑预告及目录

上一期:化学相关:水

下一期:化学相关:碳与碳的氧化物

化学反应前后,很多东西都变了。很多东西也没变,比如说元素的种类,原子的个数,但在微观现象还没被认知的时候,人们还不知道微观上的原子个数不变,也推导不出质量不变。

化学之父小作坊主拉瓦锡在1774年通过精确的定量实验研究了氧化汞(\rm HgO)的分解和合成反应中各物质质量之间的变化关系。他将45.0份质量的氧化汞加热分解,恰好得到了41.5份质量的汞和3.5份质量的氧气,反应前后各物质的质量总和没有改变。

由此我们可以得出结论,参加化学反应的各物质质量总和等于反应后生成的各物质的质量总和。也就是,化学反应前后,质量守恒。这个规律,就是质量守恒定律

质量守恒定律只能解释化学变化,并且,所有化学反应都遵守质量守恒定律

其微观解释,就是因为化学反应的本质是分子破裂成原子,原子重新组合成新分子,而原子的种类数目质量不变,元素的种类质量也不变。自然质量是不变的。而分子种类与物质种类一定发生改变,分子个数可能发生改变。

一、质量守恒定律的探究

我们之前在探究空气中氧气的含量的实验时使用了红磷燃烧。这一次也可以。

1、通过红磷燃烧

在底部铺有细沙的锥形瓶中,放入一小堆干燥的红磷,在锥形瓶口的橡胶塞上安装一根玻璃管,在其上端系牢一个小气球,并使玻璃管下端能与红磷接触。将锥形瓶和玻璃管放在托盘天平上用砝码平衡,记录所称的质量。

然后,取下锥形瓶,将橡胶塞上的玻璃管放到酒精灯火焰上灼烧至红热后,迅速用橡胶塞将锥形瓶塞紧,并将红磷引燃。待锥形瓶冷却后,重新放到托盘天平上,记录所称的质量。

我们会发现,两次的质量相等。

关于如何使用托盘天平,请参见初中物理教科书。(停顿)我们在此处再次给出如何使用托盘天平。

把天平放在水平工作台上。取下垫圈,将游码移至称量标尺左端的“0”刻度线。调节平衡螺母,直至天平横梁平衡。(停顿)

但在化学这门学科中,一般使用定量方法的时候,都是先将对应质量的砝码放在右盘,把游码调节至对应质量的刻度处,再放置物质至左盘,与物理需要知道物质的质量不同。

称量干燥的固体药品之前,应该在两个托盘上各放一张干净的大小相同的纸片(称量纸),然后把药品放在纸上称量。易潮解的药品(比如氢氧化钠),必须放在玻璃器皿(如小烧杯、表面皿)里称量。

因此,我们其实可以不去记录质量的准确数字,而是观察反应前后,天平是否都平衡。

2、通过铁与硫酸铜溶液反应

在锥形瓶中加入适量稀硫酸铜溶液(\rm CuSO_4),塞好橡胶塞。将几根铁钉用砂纸打磨干净,将盛有硫酸铜溶液的锥形瓶和铁钉一起放在托盘天平上称量,记录所称的质量。

将铁钉浸到硫酸铜溶液中,观察实验现象。待反应一段时间后溶液颜色改变时,将盛有硫酸铜溶液和铁钉的锥形瓶放在托盘天平上测量,记录所称的质量。

我们可以观察到,锥形瓶内,铁钉表面生成红色固体,溶液颜色从蓝色变成浅绿色,两次质量又一次相等了。反应表达式如下。

\rm Fe+CuSO_4\longrightarrow Cu+FeSO_4

通过盐酸与碳酸钠粉末反应

把盛有盐酸的小试管小心地放入装有碳酸钠粉末的小烧杯中,将小烧杯放在托盘天平上用砝码平衡。取下小烧杯,并将其倾斜,使小试管中的盐酸进入小烧杯中,观察现象。反应进行一段时间以后,再把烧杯放回托盘天平。天平是否仍然平衡呢?

反应表达式如下。

\rm HCl+Na_2CO_3\longrightarrow NaCl+H_2O+CO_2

我们观察到,小烧杯中产生大量气泡,天平指针向右偏转。

不是说化学反应前后质量守恒吗?为什么这次没有平衡呢?

观察反应的表达式。我们发现,生成物中有二氧化碳气体。气体在反应时会逸出烧杯,所以,我们在反应后称量的质量,并不是反应生成物的质量而是反应生成物中固体和液体质量。反应后生成的二氧化碳的质量并没有称量在内。根据质量守恒的内容,参加化学反应的各物质质量总和等于反应后生成的各物质的质量总和,我们发现,这个反应依然遵循质量守恒定律。

我们还可以通过镁条燃烧来探究。这里不再展开。我们在分析这个实验的时候,要注意,生成物并不是气体,但是,生成物附着在其他物体的表面,因而称量的质量也不都是生成物的质量。

通过质量守恒定律,我们可以改进原有的反应表达式,变成化学方程式来定量计算。

二、化学方程式

书写化学方程式有几个原则。

  • 以客观事实为依据
  • 遵守质量守恒定律

书写步骤(以电解水为例)

1、写

\rm H_2O -\!\!\!-\!\!\!-\!\!\!-\!\!\!- H_2+O_2

2、配(配平)

要让左边反应物的各元素的原子个数等于右边生成物的各元素的原子个数。

\rm 2H_2O =\!=\!=\!=2H_2+O_2

3、标

在等号上方标注反应的条件。还要在生成物侧根据要求,标上气体生成符号“↑”和沉淀符号“↓”。

\rm 2H_2O\overset{\text{Electrify}}{=\!=\!=\!=\!=}2H_2\uparrow +O_2\uparrow

气体生成符号一般根据“前无后有”的原则,也就是说反应物中,如果没有气体,而生成物中有气体,要在相应的化学式后,加上等高的↑。

例如:

\rm 2NO+O_2+4CO\overset{Catalyst}{=\!=\!=\!=\!=\!=}N_2+4CO_2

反应物与生成物中都有气体,则不打气体生成符号。条件的中文一般写作催化剂

再例如:

\rm 3Fe+4H_2O\overset{High\;temperature}{=\!=\!=\!=\!=\!=\!=\!=\!=\!=\!=}Fe_3O_4+4H_2

高温条件下,水是气态的,因此氢气后不打气体生成符号。

在高中教学中,会学习一些其他的化学方程式,比如热化学方程式。这要求在化学式后书写括号,在内部标注物质的状态:g(即 gaseous,气态的)、l(liquid,液态的)、s(solid,固态的)、aq(aqueous,水溶液的),晶体有时还要标注晶系。初中化学不做要求。

但是,我们可以在水后面标注状态来区分。

\rm 3Fe+4H_2O(g)\overset{High\;temperature}{=\!=\!=\!=\!=\!=\!=\!=\!=\!=\!=}Fe_3O_4+4H_2

初中化学,考试时请一定不要标注状态,只要标注气体生成符号和沉淀符号。

沉淀符号一般遵循“前溶后沉”的原则。也就是说,溶液中的反应如果反应物和生成物中都有固体,就不打沉淀符号。

例如二氧化碳通入澄清石灰水:

\rm CO_2+Ca(OH)_{2}=\!=\!=CaCO_3 \downarrow +H_2O

再例如(不完整请拖动):

CuSO4 + 2NaOH ═══ Na2SO4 + Cu(OH)2

在这里有一个练习,配平以往文章中出现的反应表达式。这里再给出一个(条件已给出)。

\rm TiCl_4+Mg\overset{High\;temperature}{-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!-}Ti+MgCl_2

点击查看答案。

\rm TiCl_4+2Mg\overset{High\;temperature}{=\!=\!=\!=\!=\!=\!=\!=\!=\!=\!=}Ti+2MgCl_2

三、利用化学方程式进行简单计算

我们现在谈一谈化学方程式的含义。就以点燃氢气为例。

\rm \underset{2\times\left(1\times 2\right)}{2H_2}+\underset{16\times 2}{O_2}\overset{\text{Fire}}{=\!=\!=}\underset{2\times\left(1\times 2+16\right)}{2H_2O}

下方标注的算式是各物质的质量份数。计算结果为:4、32、36。

宏观上,它表示,氢气和氧气在点燃的条件下生成了水。

微观上,它表示,每两个氢分子和一个氧分子点燃时生成两个水分子。

质量上,它表示,每4份质量的氢气和每32份质量的氧气完全反应生成36份质量的水。

例:31.6克的高锰酸钾受热完全分解,可以生成多少氧气?

答题格式如上。

下一期,碳与碳的氧化物,记得来看。

Lake桑

2019.1.19

化学相关:水

目录:化学相关:开坑预告及目录

上一期:化学相关:我们需要更深入些

下一期:化学相关:化学方程式

水是生命之源。也许你旁边就放着水杯,可能还是保温杯,可能还泡着枸杞(梗注意)。

那么,你知道现代城市里的水是如何净化的吗?我们喝的水是纯净水吗?为什么要珍惜爱护水资源?化学式与化合价又是什么?

一、水资源与水的净化

地理课上说过,地球,更应该说成“水球”——约百分之七十一的表面都被海水覆盖着。但是人类真正可利用的淡水资源并不多,再加上污染,水资源在一些地区都算得上稀罕物了。

海水淡化技术比较困难,又无法推广直接净化尿液和粪便来获得水,那就只有先利用好我们有的淡水资源。

自然界的水,通常含有不溶性杂质和可溶性杂质。不溶性杂质,一般来说就是泥沙,会使水浑浊。可溶性杂质会使水带上颜色与气味。

我们按照一定的顺序来净化水资源。

首先,收集到的自然界的水,要进入沉淀池静置。静置的目的是使悬浊液[1]在之后的步骤中能够更好地固液分离。通过在水中加入明矾(\rm KAl(SO_4)_3\cdot 12H_2O)或者其他絮凝剂生成的胶状物来吸附更小的不溶性杂质,使效果更好。

[1]:100纳米不溶的固体小颗粒悬浮于液体里形成的混合物叫悬浊液。这种状态不稳定,静置会导致固体颗粒沉降,即出现分层。

然后。我们要把这些大的杂质过滤掉。

过滤示意图
实验室过滤的常用仪器

过滤的目的就是做到真正的固液分离。

如图,实验室过滤一般需要烧杯、漏斗、玻璃棒和铁架台,其中前三个是玻璃仪器。我们还需要在漏斗内壁上紧贴滤纸(一种实验耗材,故不是仪器),做到没有气泡,不让过滤速度过慢。滤纸边缘要低于漏斗边缘,防止溅出。漏斗下端要紧贴下方烧杯内壁,玻璃棒下端要紧靠在滤纸三层的那一面。然后,将装有要过滤的液体的烧杯的口紧靠在玻璃棒上,水流应该做到顺着玻璃棒流下,即玻璃棒起到引流的作用。水流滴完时,若还浑浊,可以再过滤一遍,或者检查滤纸是否破损,过滤时漏斗内液面是否高于滤纸边缘。

一般来说,自来水的过滤是通到过滤池里,里面会有石头,从粗到细,就类似于大滤纸,山中的水流也是因为水中的鹅卵石才清澈。

接着吸附可溶性杂质,自来水一般就通到吸附池里。而活性炭的疏松多孔结构也正好适合吸附。色素和异味会跑到这些孔里面,于是可溶性杂质就去除了。但是你并不是要把活性炭直接丢水里。活性炭净水器,一般是将水从活性炭层的下方通入,上方出来较为纯净的水。

再接着,通入氯气(\rm Cl_2)等物质消毒,杀死水中的一些微生物,就是我们喝的自来水了。

但是以上步骤并不能把水变成纯水,也就是还是有杂质。部分地区的水中含有较多可溶性的钙镁化合物,称为硬水,相对较少的就是软水。加入肥皂水可以检验。若泡沫多就是软水,浮渣多就是硬水。硬水浪费肥皂,影响锅炉的正常使用,所以日常生活中会煮沸水,实验室则是蒸馏

蒸馏应用了不同的物质沸点一般不同的原理,将原来水中的水先汽化为水蒸气,再冷凝,液化形成蒸馏水。这样的水,一般就视作纯水了。但由于这样的水中缺少矿物质,一般不作为饮用水,只当成实验用品。

二、水的组成

根据化学反应前后元素种类不变,我们可以让水发生分解反应,或者有什么反应只生成水探究生成物中有什么元素,推理出水中有什么元素。

1、通过氢气燃烧

氢气是一种无色无味的气体,难溶于水,密度比水小。氢气可燃,如果是纯氢气,燃烧时无声,淡蓝色火焰,放热,通过在火焰上方罩干冷烧杯等检验方式,我们可以得出,氢气与氧气在点燃的条件下反应生成水。反应的表达式如下。

\rm H_2+O_2\overset{\text{Fire}}{\longrightarrow}H_2O

由此我们可以得出,水是由氢元素和氧元素组成的。

点燃氢气需要注意氢气纯度是否足够,否则可能会爆炸。先取样,若点燃发出尖锐爆鸣声,则不纯,响声较小则较纯。

2、通过电解水

在电解器玻璃管里加满水(最好加入少量硫酸钠(\rm Na_2SO_4)或氢氧化钠(\rm NaOH)),接通直流电源,观察到两个电极上均产生了气泡。切断电源,用燃着的木条分别在两个玻璃管尖嘴口检验电解反应中产生的气体。我们可以发现,正极的气体燃烧的更旺,负极的气体可燃,并且发出淡蓝色火焰。正极产生的气体体积与负极产生的气体体积之比为\dfrac{1}{2}。由此,我们可以知道,正极产生的是氧气,负极产生的是氢气。表达式如下。

\rm H_2O\overset{\text{Electrify}}{-\!\!\!-\!\!\!-\!\!\!-\!\!\!-\!\!\!\rightarrow}H_2+O_2

中文,反应条件一般写作通电

通电只使用直流电源。水中添加的硫酸钠和氢氧化钠只是为了增强水的导电性,不是催化剂。

我们可以再一次地得出结论,水是由氢元素和氧元素组成的。

三、对物质再一次分类

像水这样,组成中含有不同种元素的纯净物叫做化合物,比如二氧化碳,氧化铁(\rm Fe_2O_3),高锰酸钾,等等。由两种元素组成的化合物中,其中一种元素是氧元素的叫做氧化物,比如上例中的二氧化碳和氧化铁。由同种元素组成的纯净物叫做单质。比如氢气、氧气、氮气、氯气、铁、碳等等都是。

四、化学式与化合价

1、化学式

用元素符号和数字的组合表示,物质的组成的式子,叫做化学式。之前所说的化学符号大体上都是指化学式。每种纯净物的组成是固定不变的,所以表示每种物质组成的化学式只有一个。在前面文章的选读部分,我们也知道了,一个化学式可能对应不同的物质(e.g. \rm C_2H_6O可以表示酒精与二甲醚两种物质),一般来说,是因为分子的原子组成相同,但原子的排列或结构不同,导致它们的化学式相同。在以后的学习中,我们将会学习分子式,但在初中教学中,一律使用化学式,不使用分子式。

化学式 \rm H_2O 可以表示四种含义。它可以表示:水这种物质,水由氢元素和氧元素组成,一个水分子,一个水分子由两个氢原子和一个氧原子构成。

由离子构成的物质中不存在一个个的分子,其化学式表示了该物质中各元素原子数的最简整数比。

在书写化合物的化学式时,当某种组成元素原子个数比是1的时候省略不写。氧化物化学式的书写,一般把氧的元素符号写在右边,另一种元素的符号写在左边。由金属元素与非金属元素组成的化合物,书写化学式时,一般把金属元素的化学符号写在左边,非金属元素的元素符号写在右边。

至于这么写的原因,我们马上就来讲。

2、化合价

初中教学中,一般不涉及化合价的定义。此处我们给出来。

化合价是一种元素的一个与其他元素的原子化合(即构成化合物时)表现出来的性质。

摘自 百度百科

这个定义看起来比较难懂,但是我们可以知道,化合价的来源就是最外层电子得失的情况。

化合价有固定的标记方法,以及它的意义。比如\rm H_2\overset{-1}{O_2}中,氧元素上方的数字“-1”表示,在过氧化氢中,氧元素显-1价。

在化合物里,正负化合价的代数和为零。利用这个,我们可以检查并观察化学式的规律。

这里给出记诵的口诀,里面包含了元素最常见的化合价。

钾钠氢银正一价,
钙镁钡锌正二价。
氟氯溴碘负一价,
通常氧为负二价。
一二铜,二三铁,
三铝四硅五价磷。
莫忘单质价为零。

一般来说,化合物中,金属元素显正价,非金属元素显负价。当然不是绝对的。

通过化合价,我们可以写出只知道名字未知化学式物质的化学式,计算物质中的元素质量比,与相对分子质量。

下一期,讲化学方程式。记得来看哦。

Lake桑

2019.1.18

每日一词:teetotaler(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 18, 2019 is:

teetotaler • \TEE-TOH-tuh-ler\  • noun

: one who practices or advocates teetotalism : one who abstains completely from alcoholic drinks

Examples:

“… he is one of those fit older people who have redefined what 74 can look like. It probably helps that he is a teetotaler, a choice he made as a young man, having been disturbed by the effect that alcohol had on members of his family.” — David Kamp, Vanity Fair, December 2017

“The names Rockefeller and Diego Rivera are forever intertwined thanks to the Mexican artist’s infamous mural at Rockefeller Center, which the family commissioned in 1932 and had demolished two years later—due in part to its depiction of the teetotaler John D. Rockefeller Jr. sipping a martini.” — Adam Rathe, Town & Country, May 2018

Did you know?

A person who abstains from alcohol might choose tea as his or her alternative beverage, but the word teetotaler has nothing to do with tea. More likely, the “tee” that begins the word teetotal is a reduplication of the letter “t” that begins total, emphasizing that one has pledged total abstinence. In the early 1800s, tee-total and tee-totally were used to intensify total and totally, much the way we now might say, “I’m tired with a capital T.” “I am now … wholly, solely, and teetotally absorbed in Wayne’s business,” wrote the folklorist Parson Weems in an 1807 letter. Teetotal and teetotaler first appeared with their current meanings in 1834, eight years after the formation of the American Temperance Society.


Lake桑

January 18, 2019 at 01:00PM

又一个周五!


周五中午啦~ 吃完午饭,下午继续工作! (由 IFTTT 发送)

Lake桑

January 18, 2019 at 12:00PM

每日一词:farouche(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 17, 2019 is:

farouche • \fuh-ROOSH\  • adjective

1 : unruly or disorderly : wild

2 : marked by shyness and lack of social graces

Examples:

“Though she wrote three ‘novels’ (more extended free associations than novels as we know them), she is best thought of as a poet of small, farouche poems illustrated with doodles….” — Rosemary Dinnage, The New York Review of Books, 25 June 1987

“Jeremy Irons’s natural mode as an actor is fastidious rather than farouche, but he perfectly captures James Tyrone’s professional extravagance and personal meanness.” — Michael Arditti, The Sunday Express, 11 Feb. 2018

Did you know?

In French, farouche can mean “wild” or “shy,” just as it does in English. It is an alteration of the Old French word forasche, which derives via Late Latin forasticus (“living outside”) from Latin foras, meaning “outdoors.” In its earliest English uses, in the middle of the 18th century, farouche was used to describe someone who was awkward in social situations, perhaps as one who has lived apart from groups of people. The word can also mean “disorderly,” as in “farouche ruffians out to cause trouble.”


Lake桑

January 17, 2019 at 01:00PM

每日一词:nomothetic(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 16, 2019 is:

nomothetic • \nah-muh-THET-ik\  • adjective

: relating to, involving, or dealing with abstract, general, or universal statements or laws

Examples:

“Moreover, there is the often-incorrect assumption that crimes and offenders are sufficiently similar to be lumped together for aggregate study. In such cases the resulting nomothetic knowledge is not just diluted, it is inaccurate and ultimately misleading.” — Brent E. Turvey, Criminal Profiling, 2011

“First, they can expect to find an investigation of the ways in which males and females differ universally: that is, of the nomothetic principles grounded in biology and evolutionary psychology that govern sex-differentiated human development.” — Frank Dumont, A History of Personality Psychology, 2010

Did you know?

Nomothetic is often contrasted with idiographic, a word meaning “relating to or dealing with something concrete, individual, or unique.” Where idiographic points to the specific and unique, nomothetic points to the general and consistent. The immediate Greek parent of nomothetic is a word meaning “of legislation”; the word has its roots in nomos, meaning “law,” and thetēs, meaning “one who establishes.” Nomos has played a part in the histories of words as varied as metronome, autonomous, and Deuteronomy. The English contributions of thetēs are meager, but thetēs itself comes from tithenai, meaning “to put,” and tithenai is the ancestor of many common words ending in –thesishypothesis, parenthesis, prosthesis, synthesis, and thesis itself—as well as theme, epithet, and apothecary.


Lake桑

January 16, 2019 at 01:00PM

每日一词:liaison(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 15, 2019 is:

liaison • \LEE-uh-zahn\  • noun

1 : a binding or thickening agent used in cooking

2 a : a close bond or connection : interrelationship

b : an illicit sexual relationship : affair

3 a : communication for establishing and maintaining mutual understanding and cooperation (as between parts of an armed force)

b : a person who establishes and maintains communication for mutual understanding and cooperation

4 : the pronunciation of an otherwise absent consonant sound at the end of the first of two consecutive words the second of which begins with a vowel sound and follows without pause

Examples:

“Brennan and Alejandro Castro agreed on a series of steps to build confidence. One called for the Cubans to post an officer in Washington to act as a formal liaison between the two countries’ intelligence agencies.” — Adam Entous, The New Yorker, 19 Nov. 2018

“… the book offers vignettes that describe Smith’s childhood as the youngest of seven Irish-American kids in Chicago; his sister’s short liaison with a married British man who shared the surname Smith; and a panicked hashish trip in Amsterdam.” — Kirkus Reviews, 1 Dec. 2018

Did you know?

If you took French in school, you might remember that liaison is the term for the phenomenon that causes a silent consonant at the end of one word to sound like it begins the next word when that word begins with a vowel, so that a phrase like beaux arts sounds like \boh zahr\. We can thank French for the origin of the term, as well. Liaison derives from the Middle French lier, meaning “to bind or tie,” and is related to our word liable. Our various English senses of liaison apply it to all kinds of bonds—from people who work to connect different groups to the kind of relationship sometimes entered into by two people who are attracted to one another.


Lake桑

January 15, 2019 at 01:00PM

语文相关:觊觎

解释:

  1. (动)企图获取(非分的东西)
  2. (名)非分的愿望或企图

例句:

  • 祖国的领土,岂容列强觊觎!
  • 觊觎大位 | 心怀觊觎

相关文献:左传·桓公二年》:庶人、工、商,各有分亲,皆有等衰。是以民服事其上,而下无觊觎。杜预注:下不冀望上位。

Lake桑

2019.1.14

每日一词:mea culpa(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 14, 2019 is:

mea culpa • \may-uh-KOOL-puh\  • noun

: a formal acknowledgment of personal fault or error

Examples:

The mayor’s public mea culpa for his involvement in the scandal didn’t satisfy his critics.

“The internal investigation ended with a mea culpa from the sheriff’s department and a reprimand and reassignment for a deputy overseeing the property room.” — Allie Morris, The Houston Chronicle, 15 Nov. 2018

Did you know?

Mea culpa, which means “through my fault” in Latin, comes from a prayer of confession in the Catholic Church. Said by itself, it’s an exclamation of apology or remorse that is used to mean “It was my fault” or “I apologize.” Mea culpa is also a noun, however. A newspaper might issue a mea culpa for printing inaccurate information, or a politician might give a speech making mea culpas for past wrongdoings. Mea culpa is one of many English terms that derive from the Latin culpa, meaning “guilt.” Some other examples are culpable (“meriting condemnation or blame especially as wrong or harmful”), culprit (“one guilty of a crime or a fault”), and exculpate (“to clear from alleged fault or guilt”).


Lake桑

January 14, 2019 at 01:00PM

又一个周一。

一周又开始了。加油工作!(由 IFTTT 发送)

Lake桑

January 14, 2019 at 07:00AM

Minecraft 相关:你卖给村民的成书

冒险者日记

—-LakeJason

每日一词:clement(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 13, 2019 is:

clement • \KLEM-unt\  • adjective

1 : inclined to be merciful : lenient 

2 : not severe : mild

Examples:

The judge decided to be clement and said she would forgive the young defendants so long as they paid back the money they stole from the fundraiser.

“Eagle Scout Michael Eliason completed his project by literally blazing a trail: he created a half-mile-long trail along a Heights park still being developed along the Yellowstone River, Dover Park. ‘We rototilled and used pickaxes on it, and we had to wait until the weather was clement,’ he said.” — Mike Ferguson, The Billings Gazette, 24 Nov. 2014

Did you know?

Defendants in court cases probably don’t spend much time worrying about inclement weather. They’re too busy hoping to meet a clement judge so they will be granted clemency. They should hope they don’t meet an inclement judge! Clement, inclement, and clemency all derive from the Latin clemens, which means “mild” or “calm.” All three terms can refer to an individual’s degree of mercy or to the relative pleasantness of the weather.


Lake桑

January 13, 2019 at 01:00PM

每日一词:boycott(转自 韦氏词典)

原文链接


Merriam-Webster’s Word of the Day for January 12, 2019 is:

boycott • \BOY-kaht\  • verb

: to engage in a concerted refusal to have dealings with (a person, a store, an organization, etc.) usually to express disapproval or to force acceptance of certain conditions

Examples:

“Chinese boycotted Norwegian salmon over the awarding of the Nobel Peace Prize to the late dissident writer Liu Xiaobo. They stopped buying fruit from the Philippines amid a dispute over territory in the South China Sea.” — Associated Press, 13 Dec. 2018

“[Saul] Bellow … showed up at President Johnson’s White House Festival of the Arts in the summer of 1965, which other writers, such as Philip Roth (a friend and follower) and Robert Lowell, boycotted to protest against the war in Vietnam.” — Benjamin Markovits, The Spectator, 17 Nov. 2018

Did you know?

In the 1870s, Irish farmers faced an agricultural crisis that threatened to result in a repeat of the terrible famine and mass evictions of the 1840s. Anticipating financial ruin, they formed a Land League to campaign against the rent increases and evictions landlords were imposing as a result of the crisis. Retired British army captain Charles Boycott had the misfortune to be acting as an agent for an absentee landlord at the time, and when he tried to evict tenant farmers for refusing to pay their rent, he was ostracized by the League and community. His laborers and servants quit, and his crops began to rot. Boycott’s fate was soon well known, and his name became a byword for that particular protest strategy.


Lake桑

January 12, 2019 at 01:00PM