Answer:
Percentage Yield = 56.9% (to 3 significant figures)
Step-by-step explanation:
Firstly you need to calculate the amount of moles of Na used. Moles = Mass/Mr, so moles of Na = 1.72x10^-3/23. This gets you 7.47826087x10^-5 moles.
The mole ratio of Na:Na2O is 2:1 so the moles of Na2O will be the moles of Na divided by 2. This gets you 3.739130435x10^-5 moles.
Mass = Moles x Mr
The Mr of Na2O = 62
Mass = 3.739130435x10^-5 x 62 = 2.31826087x10^-3g
Percentage Yield = (Actual Yield / Theoretical Yield) x 100
Percentage Yield = (1.32x10^-3 / 2.31826087x10^-3) x 100
Percentage Yield = 56.93923481%
Percentage Yield = 56.9% (to 3 significant figures)