Sodium hydrogencarbonate decomposes when it is heated to 200 ∘C200\,^\circ\mathrm{C}200∘C.
2NaHCO3(s)→Na2CO3(…)+H2O(…)+CO2(…) \mathrm{2NaHCO_{3}(s) \rightarrow Na_{2}CO_{3}(\ldots) + H_{2}O(\ldots) + CO_{2}(\ldots)} 2NaHCO3(s)→Na2CO3(…)+H2O(…)+CO2(…)| Substance | Melting point (∘C^\circ\mathrm{C}∘C) | Boiling point (∘C^\circ\mathrm{C}∘C) |
|---|---|---|
| Sodium carbonate | 851 | 1600 |
| Water | 0 | 100 |
| Carbon dioxide | -78 | -78 |
What are the missing state symbols at 200 ∘C200\,^\circ\mathrm{C}200∘C, in the order they appear in the equation?
(s), (l), (g)
(s), (g), (g)
(aq), (l), (g)
(l), (g), (g)
55 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.