1. ## molar masses?

I don't know if i am allowed to post this here, and i apologize in advance if i am not supposed to.

but i am trying to do my homework and the book doesn't explain it too well.

how did they go from 3.50 mol of copper to 63.55 g as the molar mass?

2. Recall that molar mass is the mass in grams per 1 mol of a substance. From the periodic table, it is given that copper has a molar mass of about 63.55 g/mol. If the purpose of your question was to find the mass of the substance, notice that by multiplying the number of moles with the molar mass, the moles unit cancel and grams remain.

$3.5~\rlap{///}{\text{mol}} \times \frac{63.55~\text{g}}{1~ \rlap{///}{\text{mol}}}$