我们来解决下mole 和 gram之间的关系是怎样的：
首先我们看下mole的英文定义：the mole as the number equal to the number of carbon atoms in exactly 12 grams of pure carbon 12.
在此我们引出另外一个定义Avogadro’s number: one mole of something consists of 6.022 * 1023 units of that substance. 注意这里的1023 or 10 power to 23即10的23次方。
那么6.022 ＊ 1023 atoms of carbon (each with a mass of 12 amu) have a mass of 12 g, then
6.022 ＊ 1023 atoms (12 amu/atm) = 12 g
so 6.022 * 1023 amu = 1 g
接下来我们看一道具体的题目：
The mass of 1 mole (6.022 * 1023 atoms) of aluminum is 26.98 g 也就是我们说的 ‘atomic mass’。The sample we are considering has a mass of 10.0 g. Since the mass is less than 26.98 g, this sample contains less than 1 mole of aluminum atoms. We can calculate the number of moles of aluminum atoms in 10.0 g as follows:
10.0 g Al * (1 mol Al/26.98 g Al) = 0.371 mol Al atoms
The number of atoms in 10.0 g (0.371 mol) of aluminum is
0.371 mol Al * (6.022*1023 atoms/1 mol Al) = 2.23 * 1023 atoms