Sodium hydride ( $2.4 g$ ) is heated with excess $CO X_{2}$ to give sodium formate, which is then heated to give sodium oxalate and hydrogen. Assuming 100% yield in both steps, what mass of sodium oxalate is formed? (H = 1, C = 12, O = 16, Na = 23)

Answer: C

NaH + CO X_{2} HCOONa

and

2 HCOONa Na X_{2} C X_{2} O X_{4} + H X_{2}

. Moles of

NaH

2.4/24 = 0.10

, giving

0.10

mol formate and then

0.050

mol oxalate. Molar mass of

Na X_{2} C X_{2} O X_{4}

= 134, so mass =

0.050 \times 134 = 6.70 g