Chemistry worksheet with questions on chemical reactions and equations.

Problem Analysis:

The image contains a series of chemistry questions related to chemical reactions, types of reactions, and balancing equations. Below, I will solve each problem step by step.

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Question 7: Identify the type of reactions and write balanced chemical equations

#### (a) Zinc reacts with Silver nitrate to produce Zinc nitrate and Silver.
- Type of Reaction: Single displacement reaction.
- Balanced Equation:
\[
\text{Zn} + 2\text{AgNO}_3 \rightarrow \text{Zn(NO}_3)_2 + 2\text{Ag}
\]

#### (b) Potassium iodide reacts with Lead nitrate to produce Lead iodide and Potassium nitrate.
- Type of Reaction: Double displacement reaction.
- Balanced Equation:
\[
2\text{KI} + \text{Pb(NO}_3)_2 \rightarrow \text{PbI}_2 + 2\text{KNO}_3
\]

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Question 8: Heating blue-colored powder of copper(II) nitrate

#### (a) Identify the type of reaction and the gas X.
- Type of Reaction: Decomposition reaction.
- Gas X: Nitrogen dioxide (\(\text{NO}_2\)) is formed along with oxygen (\(\text{O}_2\)) and black copper oxide (\(\text{CuO}\)).

#### (b) Write the balanced chemical equation of the reaction.
- Balanced Equation:
\[
2\text{Cu(NO}_3)_2 \rightarrow 2\text{CuO} + 4\text{NO}_2 + \text{O}_2
\]

#### (c) Write the pH range of the aqueous solution of the gas X.
- Gas X: \(\text{NO}_2\) dissolves in water to form nitric acid (\(\text{HNO}_3\)), which is a strong acid.
- pH Range: The solution will be acidic, with a pH less than 7.

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Question 9: Classify reactions and translate statements into balanced equations

#### (a) Classify the following reactions into different types:
(i) \(\text{AgNO}_3(aq) + \text{NaCl}(aq) \rightarrow \text{AgCl}(s) + \text{NaNO}_3(aq)\)
- Type: Double displacement reaction.

(ii) \(\text{CaO}(s) + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2(aq)\)
- Type: Combination reaction.

(iii) \(2\text{KClO}_3(s) \rightarrow 2\text{KCl}(aq) + 3\text{O}_2(g)\)
- Type: Decomposition reaction.

(iv) \(\text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s)\)
- Type: Single displacement reaction.

#### (b) Translate the statement into a balanced chemical equation:
“Barium chloride reacts with aluminium sulphate to give aluminium chloride and barium sulphate.”
- Balanced Equation:
\[
3\text{BaCl}_2 + \text{Al}_2(\text{SO}_4)_3 \rightarrow 2\text{AlCl}_3 + 3\text{BaSO}_4
\]

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Question 10: Potassium iodide solution added to lead(II) nitrate

#### (a) What is the colour of this precipitate? Name the compound precipitated.
- Precipitate: Lead(II) iodide (\(\text{PbI}_2\)).
- Colour: Yellow or orange-yellow.

#### (b) Write the balanced chemical equation for this reaction.
- Balanced Equation:
\[
2\text{KI} + \text{Pb(NO}_3)_2 \rightarrow \text{PbI}_2 \downarrow + 2\text{KNO}_3
\]

#### (c) List two types of reactions in which this reaction can be placed.
- Types: Double displacement reaction, precipitation reaction.

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Question 11: Heating ferrous sulphate crystals

#### (a) List any two observations.
- Observations:
1. The greenish-blue crystals decompose, leaving a white residue.
2. A brown gas (likely sulfur dioxide, \(\text{SO}_2\)) is evolved.

#### (b) Name the type of chemical reaction taking place.
- Type of Reaction: Decomposition reaction.

#### (c) Write the balanced chemical equation for the reaction and name the products formed.
- Balanced Equation:
\[
\text{FeSO}_4 \cdot 7\text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 + \text{SO}_3 + 7\text{H}_2\text{O}
\]
- Products:
- Ferric oxide (\(\text{Fe}_2\text{O}_3\)): White solid.
- Sulfur dioxide (\(\text{SO}_2\)): Brown gas.
- Sulfur trioxide (\(\text{SO}_3\)): Gas.
- Water (\(\text{H}_2\text{O}\)): Liquid.

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Question 12: Heating copper powder

#### (a) Why has this black substance formed?
- Reason: Copper reacts with oxygen in the air to form copper(II) oxide (\(\text{CuO}\)), which is black.

#### (b) What is this black substance?
- Substance: Copper(II) oxide (\(\text{CuO}\)).

#### (c) Write the chemical equation of the reaction that takes place.
- Balanced Equation:
\[
2\text{Cu} + \text{O}_2 \rightarrow 2\text{CuO}
\]

#### (d) How can the black coating on the surface be turned reddish brown?
- Method: Heat the black copper(II) oxide in the presence of hydrogen gas (\(\text{H}_2\)). Hydrogen reduces \(\text{CuO}\) back to metallic copper.
\[
\text{CuO} + \text{H}_2 \rightarrow \text{Cu} + \text{H}_2\text{O}
\]

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Question 13: Double displacement reaction

#### (a) What is a double displacement reaction? Explain with an example.
- Definition: A reaction where two compounds exchange ions to form two new compounds.
- Example:
\[
\text{AgNO}_3(aq) + \text{NaCl}(aq) \rightarrow \text{AgCl}(s) + \text{NaNO}_3(aq)
\]

#### (b) A small amount of quick lime is added to water in a beaker.
(i) Name and define the type of reaction that has taken place.
- Type: Combination reaction.
- Definition: Two or more substances combine to form a single product.

(ii) Write the balanced chemical equation for the above reaction and the chemical name of the product formed.
- Balanced Equation:
\[
\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2
\]
- Product: Calcium hydroxide (slaked lime).

(iii) List two main observations of this reaction.
- Observations:
1. The reaction is highly exothermic, releasing heat.
2. The clear solution of calcium hydroxide forms.

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Question 14: Decomposition reaction of lead nitrate

#### (a) Design an activity to demonstrate the decomposition reaction of lead nitrate.
- Activity: Heat lead nitrate in a test tube over a Bunsen burner. Observe the formation of a yellow-brown gas and a residue.

#### (b) Draw a labelled diagram of the experimental set-up. List two main observations.
- Diagram: A test tube containing lead nitrate is heated over a Bunsen burner. A delivery tube can be used to collect the evolved gas.
- Observations:
1. A yellow-brown gas (nitrogen dioxide, \(\text{NO}_2\)) is evolved.
2. A white residue (lead(II) oxide, \(\text{PbO}\)) remains in the test tube.

#### (c) Write the balanced chemical equation for the reaction stating the physical state of the reactant and the products.
- Balanced Equation:
\[
2\text{Pb(NO}_3)_2(s) \xrightarrow{\Delta} 2\text{PbO}(s) + 4\text{NO}_2(g) + \text{O}_2(g)
\]

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Final Answers

1. Question 7:
- (a) Single displacement: \(\text{Zn} + 2\text{AgNO}_3 \rightarrow \text{Zn(NO}_3)_2 + 2\text{Ag}\).
- (b) Double displacement: \(2\text{KI} + \text{Pb(NO}_3)_2 \rightarrow \text{PbI}_2 + 2\text{KNO}_3\).

2. Question 8:
- (a) Decomposition; Gas X: \(\text{NO}_2\).
- (b) \(2\text{Cu(NO}_3)_2 \rightarrow 2\text{CuO} + 4\text{NO}_2 + \text{O}_2\).
- (c) pH < 7.

3. Question 9:
- (a) (i) Double displacement, (ii) Combination, (iii) Decomposition, (iv) Single displacement.
- (b) \(3\text{BaCl}_2 + \text{Al}_2(\text{SO}_4)_3 \rightarrow 2\text{AlCl}_3 + 3\text{BaSO}_4\).

4. Question 10:
- (a) Yellow-orange; \(\text{PbI}_2\).
- (b) \(2\text{KI} + \text{Pb(NO}_3)_2 \rightarrow \text{PbI}_2 \downarrow + 2\text{KNO}_3\).
- (c) Double displacement, precipitation.

5. Question 11:
- (a) White residue, brown gas.
- (b) Decomposition.
- (c) \(\text{FeSO}_4 \cdot 7\text{H}_2\text{O} \rightarrow \text{Fe}_2\text{O}_3 + \text{SO}_2 + \text{SO}_3 + 7\text{H}_2\text{O}\).

6. Question 12:
- (a) Formation of \(\text{CuO}\).
- (b) \(\text{CuO}\).
- (c) \(2\text{Cu} + \text{O}_2 \rightarrow 2\text{CuO}\).
- (d) Reduce with \(\text{H}_2\).

7. Question 13:
- (a) Exchange of ions; Example: \(\text{AgNO}_3 + \text{NaCl} \rightarrow \text{AgCl} + \text{NaNO}_3\).
- (b) (i) Combination, (ii) \(\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2\), (iii) Exothermic, clear solution.

8. Question 14:
- (a) Heat \(\text{Pb(NO}_3)_2\) in a test tube.
- (b) Diagram and observations: Yellow-brown gas, white residue.
- (c) \(2\text{Pb(NO}_3)_2(s) \xrightarrow{\Delta} 2\text{PbO}(s) + 4\text{NO}_2(g) + \text{O}_2(g)\).

\boxed{\text{All questions answered}}