Question 6

6.1 Study the balanced chemical equation of the reaction between sodium carbonate (Na₂CO₃) and hydrochloric acid (HCℓ) and answer the questions that follow.

Na₂CO₃ + 2HCℓ → 2NaCℓ + CO₂ + H₂O

Identify the type of reaction above. Choose between REDOX and GAS FORMING. (1)

6.2 In a reaction, 10,6 g of sodium carbonate reacts completely with excess hydrochloric acid.

6.2.1 Calculate the molar mass of sodium carbonate. (2)

6.2.2 Calculate the initial number of moles of sodium carbonate. (2)

6.2.3 Calculate the mass of CO₂ produced during this reaction. (4)

6.2.4 Calculate the mass of sodium chloride produced if 4,87 dm³ of carbon dioxide was produced at STP. (6)

6.3 14,2 g of a sample of hydrated sodium carbonate, Na₂CO₃•xH₂O, was strongly heated until no further change in mass was recorded. On heating, all the water of crystallisation evaporated as follows:

Na₂CO₃•xH₂O → Na₂CO₃+ xH₂O

Calculate the number of moles of water of crystallisation in the sodium carbonate sample, if 5,3 g of solid remained after strong heating. (5)
[20]