Determining Molar Mass

Question

Determine the molar mass potassium chloride. How many moles of potassium chloride are needed to make 100mL of a 1.0 M solution? What mass of Potassium Chloride is needed?

Please show and explain steps. Thanks!

Answer 1

Potassium chloride = KCl

molar mass = K + Cl = 39.089 + 35.453 = 74.542 g/mol

100 ml = 0.100 L

1.0 M = 1.0 mole/L

moles needed = 0.100 L x 1.0 mol/L = 0.10 moles KCl needed to make 100 ml of 1.0 M KCl

mass KCl needed = 0.100 moles x 35.453 g/mol = 3.6 g KCl needed (to 2 sig. figs.)