Moles and Molar Mass · 摩尔与摩尔质量
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| mole/məʊl/ | 摩尔 | mó ěr |
| Avogadro's number/ˌævəˈɡædrəʊz ˈnʌmbə/ | 阿伏伽德罗常数 | ā fú gā dé luó cháng shù |
| molar mass/ˈməʊlə mæs/ | 摩尔质量 | mó ěr zhì liàng |
Counting the uncountable
- You cannot count atoms one by one -- there are billions of billions.
- Yet a chemist needs to know exactly how many are in a sample.
- The trick is to weigh it, because each atom has a known heft.
- One clever number bridges the grams you weigh and the atoms you cannot see.
数不清也要数
- 你无法一个一个地数原子——数量是亿亿之多。
- 可化学家又必须准确知道样品里有多少个。
- 诀窍是称它的重量,因为每个原子都有已知的分量。
- 一个巧妙的数把你能称的克与看不见的原子连接起来。
The mole
- A mole 摩尔 is a fixed count of particles:
- That count is Avogadro's number 阿伏伽德罗常数.
- Just as "a dozen" means 12, "a mole" means $6.022\times10^{23}$.
摩尔
- 摩尔是固定数目的粒子:
- 这个数目叫阿伏伽德罗常数。
- 正如"一打"表示 12,"一摩尔"表示 $6.022\times10^{23}$。
One mole of any substance contains how many particles? · 一摩尔任何物质包含多少个粒子？
A mole is Avogadro's number of particles, $6.022\times10^{23}$. · 一摩尔是阿伏伽德罗常数个粒子，即$6.022\times10^{23}$。
Molar mass
- The molar mass 摩尔质量 is the mass of one mole, in g/mol.
- Numerically it equals the atomic or molecular mass on the periodic table.
- Water ($\text{H}_2\text{O}$) has a molar mass of about $18\ \text{g/mol}$.
摩尔质量
- 摩尔质量是一摩尔物质的质量,单位 g/mol。
- 它的数值等于周期表上的原子质量或分子质量。
- 水($\text{H}_2\text{O}$)的摩尔质量约为 $18\ \text{g/mol}$。
The molar mass of water is 2(1) + 16. What is it (in g/mol)? · 水的摩尔质量为 2(1) + 16。它的值是多少（单位 g/mol）？
$2\times1 + 16 = 18\ \text{g/mol}$.
The units of molar mass are... · 摩尔质量的单位是……
Molar mass is the mass of one mole, so g/mol. · 摩尔质量是一摩尔的质量，因此单位为 g/mol。
Grams, moles, particles
- Divide mass by molar mass to get moles: $n = \dfrac{m}{M}$.
- Multiply moles by Avogadro's number to get the particle count.
- These two steps convert between what you weigh and how many you have.
克、摩尔、粒子
- 用质量除以摩尔质量得到摩尔数:$n = \dfrac{m}{M}$。
- 用摩尔数乘以阿伏伽德罗常数得到粒子数目。
- 这两步在"你称的重量"和"你拥有的数目"之间换算。
How many moles are in $44\ \text{g}$ of $\text{CO}_2$ (molar mass $44\ \text{g/mol}$)? · $44\ \text{g}$的$\text{CO}_2$（摩尔质量$44\ \text{g/mol}$）包含多少摩尔？
$n = m/M = 44/44 = 1\ \text{mol}$.
What is the mass of $3\ \text{mol}$ of carbon atoms (molar mass $12\ \text{g/mol}$) in grams? · $3\ \text{mol}$碳原子的质量是多少克（摩尔质量$12\ \text{g/mol}$）？
$m = nM = 3\times12 = 36\ \text{g}$.
How many moles are in $36\ \text{g}$ of water?
- The molar mass of $\text{H}_2\text{O}$ is $18\ \text{g/mol}$.
- $n = \dfrac{m}{M} = \dfrac{36}{18} = 2\ \text{mol}$, which is about $1.2\times10^{24}$ molecules.
$36\ \text{g}$ 的水里有多少摩尔?
- $\text{H}_2\text{O}$ 的摩尔质量是 $18\ \text{g/mol}$。
- $n = \dfrac{m}{M} = \dfrac{36}{18} = 2\ \text{mol}$,约为 $1.2\times10^{24}$ 个分子。
Moles to grams · 摩尔转克
The mole links a count of particles to a mass you can weigh: mass is proportional to amount. · 摩尔将粒子数量与可称量的质量联系起来：质量与物质的量成正比。
Two moles of water contain about $1.2\times10^{24}$ molecules. · 两摩尔水大约含有$1.2\times10^{24}$个分子。
$2 \times 6.022\times10^{23} \approx 1.2\times10^{24}$.
Molar mass has units of g/mol -- do not confuse it with the mass of a single molecule, which is far tinier. For a compound, add the molar masses of every atom ($\text{H}_2\text{O} = 2\times1 + 16 = 18$). And match the particle: moles of atoms, moles of molecules, and moles of ions are counted separately.
摩尔质量的单位是 g/mol——别把它与单个分子的质量混淆,后者要小得多。对化合物,把每个原子的摩尔质量相加($\text{H}_2\text{O} = 2\times1 + 16 = 18$)。而且要对应粒子:原子的摩尔数、分子的摩尔数、离子的摩尔数是分别计数的。
A mole is $6.022\times10^{23}$ particles (Avogadro's number), and molar mass is the grams in one mole, read off the periodic table. Convert with $n = m/M$, then multiply by Avogadro's number for a raw count. This is how weighing a sample tells you how many atoms it holds.
一摩尔是 $6.022\times10^{23}$ 个粒子(阿伏伽德罗常数),而摩尔质量是一摩尔的克数,可从周期表读出。用 $n = m/M$ 换算,再乘以阿伏伽德罗常数得到原始数目。这就是称量样品如何告诉你它含有多少原子。