Balancing Equations and Identifying Reaction Types Quiz and Flashcards

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Questions and Answers

What is oxidation in a chemical reaction?

When a substance gains oxygen or loses hydrogen

Define reduction in a chemical reaction.

When a substance loses oxygen or gains hydrogen

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?

Magnesium is oxidised Signup and view all the answers

What is a common term used for the process of iron articles getting coated with a reddish brown powder over time?

Rusting Signup and view all the answers

Give an example of a redox reaction mentioned in the text.

CuO + H2 → Cu + H2O Signup and view all the answers

Explain what is meant by an exothermic reaction.

An exothermic reaction releases heat energy to the surroundings. Signup and view all the answers

Why is respiration considered an exothermic reaction?

Respiration is considered exothermic because it releases energy in the form of heat as glucose is broken down to release energy for cellular functions. Signup and view all the answers

Why are decomposition reactions called the opposite of combination reactions?

Decomposition reactions involve the breakdown of a single compound into simpler substances, while combination reactions involve the synthesis of a compound from simpler substances. Signup and view all the answers

What is the difference between displacement and double displacement reactions?

Displacement reactions involve an element displacing another in a compound, while double displacement reactions involve the exchange of ions between two compounds. Signup and view all the answers

Explain the concept of a precipitation reaction.

A precipitation reaction is a chemical reaction where an insoluble solid (precipitate) forms when two solutions are mixed. Signup and view all the answers

What are the three forms of decomposition reactions based on the energy supplied?

Decomposition reactions can be classified into thermal decomposition (heat energy), photochemical decomposition (light energy), and electrolytic decomposition (electricity). Signup and view all the answers

What is corrosion and how does it affect metals?

Corrosion is the process where metals are attacked by substances like moisture and acids, leading to damage. It causes the formation of coatings like black on silver and green on copper. Signup and view all the answers

How does oxidation lead to rancidity in fats and oils?

When fats and oils are oxidized, they become rancid, changing their taste and smell. Signup and view all the answers

What is the purpose of flushing bags of chips with gas such as nitrogen?

To prevent the chips from getting oxidized. Signup and view all the answers

Explain the changes in the colour of copper sulphate solution when an iron nail is dipped in it.

The iron nail reacts with copper sulphate solution, leading to the displacement of copper by iron. This results in a change in color as iron(II) sulfate is formed. Signup and view all the answers

Give an example of a double displacement reaction.

An example of a double displacement reaction is the reaction between sodium chloride and silver nitrate, which forms sodium nitrate and silver chloride. Signup and view all the answers

Identify the substances that are oxidized and reduced in a chemical reaction.

In a chemical reaction, the substance that loses electrons is oxidized, while the substance that gains electrons is reduced. Signup and view all the answers

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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.