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Questions and Answers
What is oxidation in a chemical reaction?
What is oxidation in a chemical reaction?
When a substance gains oxygen or loses hydrogen
Define reduction in a chemical reaction.
Define reduction in a chemical reaction.
When a substance loses oxygen or gains hydrogen
Explain what happens in a redox reaction.
Explain what happens in a redox reaction.
One reactant gets oxidised while the other gets reduced
Is magnesium oxidised or reduced in the reaction where it burns in air to form magnesium oxide?
Is magnesium oxidised or reduced in the reaction where it burns in air to form magnesium oxide?
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What is a common term used for the process of iron articles getting coated with a reddish brown powder over time?
What is a common term used for the process of iron articles getting coated with a reddish brown powder over time?
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Give an example of a redox reaction mentioned in the text.
Give an example of a redox reaction mentioned in the text.
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Explain what is meant by an exothermic reaction.
Explain what is meant by an exothermic reaction.
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Why is respiration considered an exothermic reaction?
Why is respiration considered an exothermic reaction?
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Why are decomposition reactions called the opposite of combination reactions?
Why are decomposition reactions called the opposite of combination reactions?
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What is the difference between displacement and double displacement reactions?
What is the difference between displacement and double displacement reactions?
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Explain the concept of a precipitation reaction.
Explain the concept of a precipitation reaction.
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What are the three forms of decomposition reactions based on the energy supplied?
What are the three forms of decomposition reactions based on the energy supplied?
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What is corrosion and how does it affect metals?
What is corrosion and how does it affect metals?
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How does oxidation lead to rancidity in fats and oils?
How does oxidation lead to rancidity in fats and oils?
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What is the purpose of flushing bags of chips with gas such as nitrogen?
What is the purpose of flushing bags of chips with gas such as nitrogen?
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Explain the changes in the colour of copper sulphate solution when an iron nail is dipped in it.
Explain the changes in the colour of copper sulphate solution when an iron nail is dipped in it.
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Give an example of a double displacement reaction.
Give an example of a double displacement reaction.
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Identify the substances that are oxidized and reduced in a chemical reaction.
Identify the substances that are oxidized and reduced in a chemical reaction.
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Study Notes
Chemical Reactions
- Oxidation in a chemical reaction: the loss of one or more electrons by an atom, molecule, or ion.
- Reduction in a chemical reaction: the gain of one or more electrons by an atom, molecule, or ion.
Redox Reactions
- A redox reaction is a chemical reaction involving oxidation and reduction processes simultaneously.
- Example: combustion of magnesium to form magnesium oxide (Mg → MgO); magnesium is oxidized (loses electrons), and oxygen is reduced (gains electrons).
Corrosion and Rancidity
- Corrosion: the deterioration of metals, especially iron, due to oxidation reactions, resulting in a reddish-brown powder (rust).
- Oxidation leads to rancidity in fats and oils, spoiling their quality and flavor.
Reaction Types
- Exothermic reaction: a chemical reaction that releases heat energy, often accompanied by an increase in temperature.
- Respiration is considered an exothermic reaction as it releases energy in the form of heat.
- Decomposition reactions: the breakdown of a single compound into two or more simpler substances; opposite of combination reactions.
- Displacement reaction: a reaction where one element displaces another from a compound; e.g., Zn + CuSO₄ → ZnSO₄ + Cu.
- Double displacement reaction: a reaction where two compounds exchange partners; e.g., NaCl + AgNO₃ → NaNO₃ + AgCl.
- Precipitation reaction: a reaction where an insoluble solid (precipitate) forms from a solution; e.g., mixing NaCl and AgNO₃.
Decomposition Reactions
- Decomposition reactions can be classified into three types based on the energy supplied:
- Thermal decomposition: uses heat energy; e.g., 2H₂O → 2H₂ + O₂.
- Photodecomposition: uses light energy; e.g., 2H₂O + light → 2H₂ + O₂.
- Electrolytic decomposition: uses electric energy; e.g., 2H₂O → 2H₂ + O₂.
Miscellaneous
- Flushing bags of chips with gas (e.g., nitrogen) prevents oxidation and spoilage.
- The color change of copper sulphate solution when an iron nail is dipped in it is due to the formation of iron(II) sulphate, which has a greenish color.
- Example of a double displacement reaction: NaCl + AgNO₃ → NaNO₃ + AgCl.
- In a chemical reaction, the substances that are oxidized and reduced can be identified by tracking the loss and gain of electrons.
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Description
Test your knowledge of balancing chemical equations and identifying reaction types with this quiz. Practice writing balanced equations for reactions like calcium hydroxide + carbon dioxide producing calcium carbonate + water, and identifying reactions like double displacement or precipitation. Challenge yourself with equations involving potassium bromide, barium iodide, zinc carbonate, zinc oxide, and carbon dioxide.