# Question #a279a

##### 1 Answer

#### Explanation:

The key here is the fact that **mole** of any element contains **atoms** of that element, as given by **Avogaro's constant**.

So if your sample contains **mole** of iron, it contains **atoms** of iron. Similarly, if a sample contains **mole** of potassium, it contains **atoms** of potassium.

Now, you know that iron has a **molar mass** of **mole** of iron, it will have a mass of **atoms** of irion, the equivalent of **mole** of iron, havea mass of

Potassium has a **molar mass** of **mole** of potassium has a mass **atoms** of potassium have a mass of

So, use this to find the number of atoms of potassium present in

#780 color(red)(cancel(color(black)("g"))) * (6.022 * 10^(23) quad "atoms K")/(39.0983 color(red)(cancel(color(black)("g")))) = 120.137 * 10^(23) quad "atoms K"#

Now all you have to do is to figure out how many grams of iron will contain **atoms** of iron.

#120.137 * color(blue)(cancel(color(black)(10^(23)))) color(red)(cancel(color(black)("atoms Fe"))) * "55.845 g"/(6.022 * color(blue)(cancel(color(black)(10^(23)))) color(red)(cancel(color(black)("atoms Fe")))) = color(darkgreen)(ul(color(black)("1100 g")))#

The answer is rounded to two **sig figs**, the number of sig figs you have for the mass of iron.

Notice that because **mole** of atoms of iron is heavier than **mole** of atoms of potassium, which is essentially saying that **atom** of iron is heavier than **atom** of potassium, the mass of iron that contains the same number of atoms as the number of atoms of potassium present in