IB myp 4-5 Chemistry – Practice Questions- All Topics
Topic :Types of chemical reaction-Redox Reactions
Topic :Types of chemical reaction-Weightage : 21 %
All Questions for Topic :acids and bases,neutral solutions,acid/base reactions,$\mathrm{pH}$ and indicators,formation of salts,uses of salts,redox reactions,reactivity series,extraction of metals and corrosion,electrochemical cells
Question:
For each of the following ionic equations:
a) Balance the equation so the net charge is the same on each side of the equation
b) Construct the two half-equations from the ionic equation
c) Balance the charges for each half-equation by adding electrons
d) Identify the species that is being oxidized and the species being reduced.
Cu2+ + Mg ➝ Cu + Mg2+
Al + Fe3+ ➝ Al3+ + Fe
Ag+ + Cd ➝ Cd2+ + Ag
Sn + Pb2+ ➝ Sn4+ + Pb
▶️Answer/Explanation
Ans: Reaction 1
Cu2+ + Mg → Cu + Mg2+
Cu2+ + 2e– → Cu
Mg → Mg2+ + 2e–
Cu2+ ion is being reduced and Mg atom is being oxidized.
Reaction 2
Al + Fe3+ → Al3+ + Fe
Fe3+ + 3e– → Fe
Al → Al3+ + 3e–
Fe3+ ion is being reduced and Al atom is being oxidized.
Reaction 3
2Ag+ + Cd → Cd2+ + 2Ag
2Ag+ + 2e– → 2Ag
Cd → Cd2+ + 2e–
Ag+ ion is being reduced and Cd atom is being oxidized.
Reaction 4
Sn + 2Pb2+ → Sn4+ + 2Pb
2Pb2+ + 4e– → 2Pb
Sn → Sn4+ + 4e–
Pb2+ ion is being reduced and Sn atom is being oxidized.
Question:
Construct the half-equations for the rusting of iron.
▶️Answer/Explanation
Ans: 4Fe(s) + 3O2(g) → 2Fe2O3(s)
Fe → Fe2+ + 2e–
½O2 + 2e– → O2–
The second step in this process to form hydrated iron oxide is a multi–step process and beyond requirements of this curriculum.
Summative assessment
Question:
Combustion reactions are an example of an oxidation reaction.
a) What is a combustion reaction? Illustrate your answer with a word equation or balanced chemical equation.
▶️Answer/Explanation
Ans: A combustion reaction is a combination of a substance with an oxidant, normally oxygen, to produce heat and new products. An example is the combustion of methane gas with oxygen to produce carbon dioxide, water and heat.
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
b) Give three examples of combustion reactions that play a role in your daily life.
▶️Answer/Explanation
Ans: Examples may include cellular respiration, the combustion of fuels in transport vehicles, the burning of coal in power generation plants that provide electricity to your home.
c) Explain the difference between complete and incomplete combustion reactions.
▶️Answer/Explanation
Ans: Complete combustion occurs when there is sufficient or an excess of oxygen for the reaction to occur; products include carbon dioxide and water; incomplete combustion is the result of a lack of sufficient oxygen; products include elemental carbon or carbon monoxide and water.