Question

How many grams of sodium chloride are present in a 0.75 M solution with a volume of 500.0 milliliters?

Answer 1

number of moles = molarity X volume in L = 0.75 X 500/1000 = 0.375

molar mass of NaCl = 58.44 g/mole

it means that 1 mole of NaCl = 58.44 g

so 0.375 moles of NaCl = 0.375 X 58.44 = 21.915 g

Answer 2

A solution of sodium chloride has a molarity of 0.75 M

molarity is defined as the number of moles of solute in 1 L of a solution

molarity of NaCl solution is 0.75 M

this means there are 0.75 mol of NaCl in 1 L of solution

1 L contains 1000 mL

so if 1000 mL of NaCl contains - 0.75 mol

then 500.0 mL of NaCl contains - 0.75 mol / 1000 x 500.0 = 0.375 mol

Molar mass of NaCl is 58.5 g/mol

so if 1 mol of NaCl weighs - 58.5 g

then 0.375 mol of NaCl weighs - 58.5 g/mol x 0.375 mol = 21.9 g

mass of NaCl in volume of 500.0 mL is 21.9 g