Determine the molarity of a 4.5 L solution that contains 100g of NaOH dissolved (Na=23 g/mol, O=16 g/mol, H=1 g/mol)?

Jun 26, 2018

0.56 mol/L or 0.56 M

Explanation:

To find molarity, we'll use this formula:

$M o l a r i t y = \text{moles of solute"/"volume of solution in L}$

We already have the volume, but we'll need to find the moles of solute (NaOH). From the given mass, we'll need to find the moles of NaOH using this:

$\text{moles" = "mass"/"molar mass"="100g"/"(23+16+1)g/mol"=100/40=2.5 mol}$

Plugging in the moles to the molarity formula:

$M o l a r i t y = \frac{\text{moles of solute"/"volume of solution in L"="2.5 mol"/"4.5L"=0.56 "mol}}{L} \mathmr{and} 0.56 M$

Either unit for molarity will be fine.