Question

Calculate the molarity of a solution given the following information: 10g NaOH dissolved in 500 mL of solution.

0.03 M
0.1 M
0.5 M
10 M

Answer 1

M= mol/L


10g NaOH x 1 mol / 40gNaOH = 0.25 mol NaOH

500mL / 1000 = 0.5 L


0.25 mol NaOH / 0.5 L = 0.5 M

Answer 2

First you calculate the number of moles of the solution :

Molar mass Of NaOH = 40.0 g/mol

number of moles = mass solute / molar mass

n = 10 / 40.0

n = 0.25 moles of NaOH

Molarity = number of moles / volume in liters

500 mL = 500 / 1000 = 0.5 L

M = 0.25 / 0,5

M = 0.5 M

Answer C

hope this helps!