Question

What is the molarity of a solution prepared by dissolving 4g of NaOH in 100mL of solution?

I get that you have to change mL to litres, but I am not sure what formula to use.

Answer 1

I got `1M`.

Explanation:

Well, first we have to convert `4g` of sodium hydroxide into moles.

`NaOH` has a molar mass of `40g"/"mol`.

So here, there exists

`(4cancelg)/(40cancelg"/"mol)=0.1mol`

Then, molarity is expressed by the equation:

`"molarity"="moles of solute"/"liters of solution"`

So now, we need to convert `100mL` into `L`.

`1L=1000mL`

`:.100mL=0.1L`

Since we have now the desired units, we plug them into the equation.

`:."molarity"="0.1mol"/"0.1L"=1mol"/"L=1M`

So, the molarity of the solution will be `1M`.