When a mixture of 60 g of carbonate and sodium bicarbonate was heated, water with a mass of 2.7 g

When a mixture of 60 g of carbonate and sodium bicarbonate was heated, water with a mass of 2.7 g was formed. calculate the mass fraction of the substance in the mixture.

Given:
mixture of Na2CO3 and NaHCO3
m (mixture) = 60 g
m (H2O) = 2.7 g
Find: w (Na2CO3) w (NaHCO3)
Decision:
Let’s compose the reaction equations:
Na2CO3 does not decompose when heated, then
2NaHCO3 = Na2CO3 + H2O + CO2
1) v (H2O) = m (H2O) / M (H2O)
v (H2O) = 2.7 / 18 = 0.15 mol.
2) the number of moles of NaHCO3 is 2 times more than Na2CO3, which means:
v (NaHCO3) = 0.3 mol
3) m (NaHCO3) = 0.3 * 84 = 25.2 g
M (NaHCO3) = 23 + 1 + 12 + 16 * 3 = 84g / mol
4) Find the shares, denoting 60 g – 100%
w (NaHCO3) = 25.2 * 100/60 = 42%
w (Na2CO3) = 100 – 42 = 58%