Question

Question #32a07

Answer 1

`C=0.2`mol/`dm^3`

Explanation:

the molar concentration C is defined as : `C=n/V`
n : amount of solute and V : Volume

we know that `n=m/M`
m : masse of the solute and M : Molar mass

the concentration will be `C=m/(M*V)`
in your exemple `V=500 cm^3 = 0.5dm^3`

M for Sodium Hydroxide NaOH is
`M=M(Na)+M(O)+M(H)`
`=22.98976+15.9994+1.00794=39.9971` g/mol

`m=4g`
so `C=4/(39.9971*0.5)=0.2`mol/`dm^3`