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)?

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Answer 1 · 2018-06-26T00:37:58

0.56 mol/L or 0.56 M

To find molarity, we'll use this formula:

$Molarity = "moles of solute"/"volume of solution in L"$

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:

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

Plugging in the moles to the molarity formula:

$Molarity = "moles of solute"/"volume of solution in L"="2.5 mol"/"4.5L"=0.56 "mol"/L or 0.56 M$

Either unit for molarity will be fine.