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Year 10
AQA
Higher

Determining an equation experimentally: sodium hydrogencarbonate

I can describe a safe experiment to calculate the stoichiometric values for the decomposition of sodium hydrogencarbonate.

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New
New
Year 10
AQA
Higher

Determining an equation experimentally: sodium hydrogencarbonate

I can describe a safe experiment to calculate the stoichiometric values for the decomposition of sodium hydrogencarbonate.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Heating sodium hydrogencarbonate in a crucible leads to its decomposition.
  2. The risk involved with heating sodium hydrogencarbonate is low.
  3. The stoichiometry for a reaction can be calculated given experimental data.
  4. 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.

This lesson presents a fantastic opportunity to bring together multiple aspects of the topic – types of reactions, conservation of mass, moles, ratios, practical skills, equipment choice, etc. Opportunities to adapt it to the needs of the class/provide extension activities is extensive!
Teacher tip

Equipment

Sodium hydrogencarbonate, spatula, weighing boat, balance, crucible + lid, clay triangle, tripod, Bunsen burner, heatproof mat, tongs.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
The formula for sodium hydrogen carbonate is NaHCO₃. Which of the following statements about sodium hydrogen carbonate are correct?
Correct answer: The ratio of sodium to oxygen is 1 : 3.
The ratio of hydrogen to oxygen is 3 : 1.
Correct answer: The ratio of carbon to sodium is 1 : 1.
The ratio of oxygen to carbon is 1 : 3.
Q2.
What is the ratio of sodium hydrogen carbonate to water in the following equation? 2NaHCO₃ → Na₂O + 2CO₂ + H₂O.
Correct answer: 2 : 1
1 : 2
2 : 2
3 : 2
Q3.
Which of the following equations shows the correct relationship between moles, mass and relative mass?
Correct answer: mass = moles × relative mass
moles = mass × relative mass
relative mass = mass × moles
moles = relative mass ÷ mass
Q4.
What type of reaction does the following chemical equation represent? CuCO₃ → CuO + CO₂.
oxidation
Correct answer: thermal decomposition
combustion
neutralisation
Q5.
Calculate the relative formula mass of sodium hydrogen carbonate, NaHCO₃. Relative atomic masses: Na = 23; H = 1; C = 12; O = 16.
Correct Answer: 84, 84.0
Q6.
Calculate the mole sof 4.2 g of sodium hydrogen carbonate, NaHCO₃. Relative formula mass of NaHCO₃ = 84.
Correct Answer: 0.05 mol, 0.05, 0.05 mole, 0.05 moles

Exit quiz

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6 Questions

Q1.
Match the following key terms to their definition.
Correct Answer:decomposition,A reaction where a reactant breaks down into two or more products.

A reaction where a reactant breaks down into two or more products.

Correct Answer:mole,The unit for amount of substance.

The unit for amount of substance.

Correct Answer:closed system,No substances can enter or leave.

No substances can enter or leave.

Correct Answer:conservation of mass,The mass of the reactants equals the mass of the products.

The mass of the reactants equals the mass of the products.

Correct Answer:molar ratio,Ratio of particles that react/form in a chemical reaction.

Ratio of particles that react/form in a chemical reaction.

Q2.
When sodium hydrogen carbonate is heated in a crucible it into sodium oxide, carbon dioxide and water.
Correct Answer: decomposes, decomposed, decompose, thermally decomposes, thermally decomposed
Q3.
Why can the crucible lid remain closed during the following reaction? 2NaHCO₃ → Na₂O + 2CO₂ + H₂O.
Correct answer: 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.
Q4.
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.
Correct Answer: 2.7 g, 2.7
Q5.
Which of the following is the balanced symbol equation for the thermal decomposition of sodium hydrogen carbonate into sodium hydroxide and carbon dioxide?
Correct answer: NaHCO₃ → NaOH + CO₂
2NaHCO₃ → 2NaOH + CO₂
NaHCO₃ → NaOH + 2CO₂
NaHCO₃ → 2NaOH + 2CO₂
Q6.
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.
Correct Answer: 0.952 g, 0.952, 0.95 g, 0.95