Determine the number of moles in each of the quantities?

Question

1. 25 g of NaCl?


2. 125 g of H2SO4

Answer 1

Divide the mass of the sample by the molar mass of the substance.

grams divided by grams per mole gives you an answer in terms of moles.

The molar mass of NaCl = 58.44 g/mol.
The molar mass of H2SO4 = 98.08 g/mol.

25 g NaCl / 58.44 g/mol = .4278 moles of NaCl
125 g H2SO4 / 98.08 g/mol = 1.274 moles of H2SO4

Answer 2

1) 0.4277 moles NaCl

2) 1.2755 moles H2SO4

Divide the number of grams of the molecule by the molecular weight of that molecule (use periodic table and add up weights of each atom in molecule).