Question

You have 47.0 mL of a 0.400 M stock solution that must be diluted to 0.100 M. Assuming the volumes are additive, how much water should you add?

Answer 1

Hey there!

Moles of stock solution:

47.0 mL in liters : 47.0 / 1000 => 0.047 L

n = M * V

n = 0.400 * 0.047

n = 0.0188 moles

Volume final :

M = n / V

0.100 = 0.0188 / V

V = 0.0188 / 0.100

V = 0.188 L =>  188 mL

Therefore Watter added :

volume final - volume initial

188 mL - 47.0 mL =>  141 mL

Hope That helps!