Carbonic acid and carbonates. Practical work 1
Answers are for parents and teachers.
1
Write NaHCO₃ + HCl in molecular and net ionic form.
NaHCO₃ + HCl → NaCl + H₂O + CO₂↑; HCO₃⁻ + H⁺ → H₂O + CO₂↑.
2
CO₂ is passed through lime water containing 74 g Ca(OH)₂. If CO₂ is not in excess, what is the largest mass of CaCO₃ that can precipitate? (M(Ca(OH)₂) = 74, M(CaCO₃) = 100)
100
3
Write reaction equations for the chain CO → CO₂ → K₂CO₃ → KHCO₃ → K₂CO₃.
2CO + O₂ → 2CO₂; CO₂ + 2KOH → K₂CO₃ + H₂O; K₂CO₃ + CO₂ + H₂O → 2KHCO₃; 2KHCO₃ → K₂CO₃ + CO₂↑ + H₂O (on heating).
4
Why is crushed limestone added to acidic soil? Write the equation.
CaCO₃ neutralises the acid: CaCO₃ + 2H⁺ → Ca²⁺ + H₂O + CO₂↑.
5
Write a report on the practical work: the two-stage change when CO₂ is passed through lime water, with equations.
1) cloudiness: Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O; 2) clearing: CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂.