Starter quiz
- The formula for sodium hydrogen carbonate is NaHCO₃. Which of the following statements about sodium hydrogen carbonate are correct?
- The ratio of sodium to oxygen is 1 : 3. ✓
- The ratio of hydrogen to oxygen is 3 : 1.
- The ratio of carbon to sodium is 1 : 1. ✓
- The ratio of oxygen to carbon is 1 : 3.
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- What is the ratio of sodium hydrogen carbonate to water in the following equation? 2NaHCO₃ → Na₂O + 2CO₂ + H₂O.
- 2 : 1 ✓
- 1 : 2
- 2 : 2
- 3 : 2
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- Which of the following equations shows the correct relationship between moles, mass and relative mass?
- mass = moles × relative mass ✓
- moles = mass × relative mass
- relative mass = mass × moles
- moles = relative mass ÷ mass
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- What type of reaction does the following chemical equation represent? CuCO₃ → CuO + CO₂.
- oxidation
- thermal decomposition ✓
- combustion
- neutralisation
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- Calculate the relative formula mass of sodium hydrogen carbonate, NaHCO₃. Relative atomic masses: Na = 23; H = 1; C = 12; O = 16.
- '84' ✓
- Calculate the mole sof 4.2 g of sodium hydrogen carbonate, NaHCO₃. Relative formula mass of NaHCO₃ = 84.
- '0.05 mol' ✓
Exit quiz
- Match the following key terms to their definition.
- decomposition⇔A reaction where a reactant breaks down into two or more products. ✓
- mole⇔The unit for amount of substance. ✓
- closed system⇔No substances can enter or leave. ✓
- conservation of mass⇔The mass of the reactants equals the mass of the products. ✓
- molar ratio⇔Ratio of particles that react/form in a chemical reaction. ✓
- When sodium hydrogen carbonate is heated in a crucible it ______ into sodium oxide, carbon dioxide and water.
- 'decomposes' ✓
- Why can the crucible lid remain closed during the following reaction? 2NaHCO₃ → Na₂O + 2CO₂ + H₂O.
- A gas is not a reactant in the reaction. ✓
- A gas is a product of the reaction.
- Carbon dioxide is made during the reaction.
- Carbon dioxide is a reactant.
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- 5.0 g of sodium hydrogen carbonate was heated in a crucible. At the end of the reaction, 2.3 g of solid remained. Calculate the mass of gaseous products produced during the reaction.
- '2.7 g' ✓
- Which of the following is the balanced symbol equation for the thermal decomposition of sodium hydrogen carbonate into sodium hydroxide and carbon dioxide?
- NaHCO₃ → NaOH + CO₂ ✓
- 2NaHCO₃ → 2NaOH + CO₂
- NaHCO₃ → NaOH + 2CO₂
- NaHCO₃ → 2NaOH + 2CO₂
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- Calculate the maximum mass of sodium hydroxide (NaOH) that can be formed from 2.00 g of sodium hydrogen carbonate during the following reaction: NaHCO₃ → NaOH + CO₂ RFM: NaHCO₃ = 84; NaOH = 40.
- '0.952 g' ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- Heating sodium hydrogencarbonate in a crucible leads to its decomposition.
- The risk involved with heating sodium hydrogencarbonate is low.
- The stoichiometry for a reaction can be calculated given experimental data.
- Because a gas is not a reactant in this reaction, the crucible lid remains closed throughout the heating process.
Common misconception
Pupils may think that the mass of the crucible and contents will not change during the reaction because the lid is closed, believing that all gases produced remain inside.
Explain that even with the crucible lid on, gases like carbon dioxide & water vapour formed during decomposition can escape around the edges. This leads to a decrease in mass, which is crucial for calculating the stoichiometry based on the mass loss.
Keywords
Decomposition - A type of reaction where a reactant compound breaks down into two or more products.
Ratio - A ratio can be used to determine the size of one quantity in relation to another.
Stoichiometry - The molar ratio of the reactants and products in a chemical reaction.
Mole - 1 mole of a substance is 6.02 × 10²³ particles of it. The mass of a mole of a substance is its relative mass in grams.
Balanced symbol equation - A reaction using a symbol equation with coefficients to ensure there are equal numbers of atoms of each element on both sides of the equation.