Question

calculate the molarity of 10.0 g of NaOH were dissolved in 500.0mL of solution

Answer 1

Hi! This probably belongs in the chemistry section, but it can be relevant to a physicist.

Anyway!

Do you know what molarity is?

Answer 2

First we have to find how many mols we have with 10.0 g of NaOH.
\[\eta=\frac{m}{MM}\]
\[MM_{NaOH}=40.0~g/mol\]
\[\eta=\frac{10.0}{40.0}\]
\[\boxed{\eta=0.25~mol}\]
now we can divide
\[molarity=\frac{\eta}{V}\]
\[V=500.0~mL=0.5~L\]
\[molarity=\frac{0.25}{0.5}\]
\[\boxed{\boxed{molarity=0.5~mol/L=0.5~M}}\]