Question

How many moles are in 987 grams of : Ra(OH)2

Answer 1

Here are the molar masses of these atoms:

Ra = 226 g/mol

H = 1.008 g/mol * 2 (there are two hydrogen atoms in radium hydroxide)

O = 15.999 g/mol * 2

The molar mass of radium hydroxide is therefore 260.014 g/mol.

Divide this number by 987 grams to cancel the units in order to obtain the number moles.

260.014 g/mol / 987 g = 0.263 mol

Answer 2

Your answer is 3.80 moles