Na2SO4 means: two moles sodium (45.98 g), one mole sulfur (32.06 g), and four moles oxygen (64.00 g) combine to form one mole of sodium sulfate (142.04 g).
<span>2.51 grams
You want to prepare 19.16 g of some solution which will have 13.1% of it's mass being sucrose. So we just need to perform some simple multiplication:
19.16g * 0.131 = 2.50996g
Rounding to 3 significant figures gives 2.51 g.</span>
