Question

How many moles of sodium oxalate. $N{a}_2{C}_2{O}_4$, are present in $6.7$ g of this compound?

(Atomic weights: $C=12,O=16,Na=23$ g/mole)

• A. $2.0$ moles
• B. $1.0$ mole
• C. $0.50$ moles
• D. $0.10$ moles
• E. $0.050$ moles

Answer 1

The correct option is E $0.050$ moles

Atomic weights: $C=12,O=16,Na=23$
The molecular weight of sodium oxalate $N{a}_2{C}_2{O}_4$ is $2\left(23\right)+2\left(12\right)+4\left(16\right)=46+24+64=134$ g/mol.
Mass of sodium oxalate is divided with its molecular weight to obtain the number of moles.
Mass of sodium oxalate $=\frac{6.7}{134}=0.050$ moles.