# Question 3e721

Oct 10, 2016

$\text{928.4 g}$

#### Explanation:

You know that chalcopyrite is 34.63% copper by mass, which essentially means that every $\text{100 g}$ of chalcopyrite contain $\text{34.63 g}$ of copper.

That is what percent concentration by mass tells you. That % sign means that you're looking at $\text{100 g}$ of a compound.

So, you know that you get $\text{34.63 g}$ of copper for every $\text{100 g}$ of chalcopyrite, and that the sample contains $\text{321.5 g}$ of copper.

You can use the ore's percent concentration by mass as a conversion factor to help you calculate the mass of ore that would contain that many grams of copper

321.5 color(red)(cancel(color(black)("g Cu"))) * "100 g ore"/(34.63color(red)(cancel(color(black)("g Cu")))) = color(green)(bar(ul(|color(white)(a/a)color(black)("928.4 g ore")color(white)(a/a)|)))#

The answer is rounded to four sig figs.