The solution contains answers to questions labeled 6 and 7. Question 6 asks about filtration, removal of CO2 and H2O before air liquefaction, identification of Argon, preparation of oxygen, and a chem

Haya hapa majibu ya maswali yako:

6.

• a) i) Identify the substance that is removed at the filtration stage.
  • Dust particles
• a) ii) Explain why carbon (IV) oxide and water are removed before liquefaction of air.
  • Carbon (IV) oxide and water vapor have higher freezing points than oxygen and nitrogen. If not removed, they would freeze and block the pipes and equipment during the cooling process, causing damage or inefficiency.
• a) iii) Identify the component that is collected at $-186^\circ\text{C}$.
  • Argon
• b) i) Complete the diagram below to shows a set-up used to prepare oxygen gas.
  • The diagram should be completed by adding a dropping funnel at the top, through which substance X (water) is added to the sodium peroxide.
• b) ii) Name substance X.
  • Water
• b) iii) Write a well balanced chemical equation to show the reaction of sodium peroxide with the substance named above. $$2\text{Na}_2\text{O}_2(s) + 2\text{H}_2\text{O}(l) \rightarrow 4\text{NaOH}(aq) + \text{O}_2(g)$$

7.

• i) On the diagram indicate what should be done for the reaction to occur.
  • Heat the copper (II) oxide in the combustion tube using a Bunsen burner.
• ii) Hydrogen gas is allowed to pass through the tube for sometime before it is lit. Explain.
  • Hydrogen gas forms an explosive mixture with air (oxygen). Passing hydrogen through the tube for some time ensures that all air is expelled from the apparatus, preventing an explosion when the hydrogen is lit or heated.
• iii) Write an equation that takes place at the combustion tube. $$\text{H}_2(g) + \text{CuO}(s) \rightarrow \text{Cu}(s) + \text{H}_2\text{O}(l)$$
• iv) What property if hydrogen is being investigated?
  • Reducing property (or its ability to act as a reducing agent).
• v) Why is Zinc oxide not used to investigate the property of hydrogen gas?
  • Zinc is more reactive than hydrogen, so hydrogen cannot reduce zinc oxide to zinc metal. Hydrogen can only reduce oxides of metals that are less reactive than itself.

8.

• Which letter represents:
  • i) NaOH: B (Strong base, pH 13.0)
  • ii) H₂SO₄: A (Strong acid, pH 2.1)
  • iii) MgCl₂: C (Salt of strong acid and strong base, neutral pH 7.0)