Question

please answer me question no 25

Answer 1

Given mass of copper sulphate=15.9g

mass of sodium sulphide=7.8g

After reaction:

mass of copper sulphide=9.5g

mass of sodium sulphate=?

According to the Law of Conservation of Mass,mass cannot be created nor be destroyed.So in this reaction mass of compounds before reaction should be equal to mass after reaction .

therefore,

⇒mass of CuSO4+ mass of Na2S=mass of Cu2S+mass of Na2SO4

⇒15.9+7.8=9.5+x

⇒23.7=9.5+x

⇒x=23.7-9.5

⇒x=14.2g

Therefore mass of sodium sulphate = 14.2g

hope it helps......................