Question 1
When Sulphur is heated the following reaction takes place.
- Name process A and B.
- State one application of the process A.
Answer
- A-
Sublimation
B - Deposition or Reverse sublimation - Use in ice vendor machine to keep ice cream frozen.
Question 2
- A student was stung by a bee outside the chemistry lab. The teacher applied a solution of ammonia to the place. Explain why.
- Explain why it is not advisable to use a solution of potassium hydroxide
Answer
- Bee sting contains methanoic acid which causes pain, ammonia neutralizes the acid relieving the pain.
- Bubbles of a yellow gas produced
- It’s a strong base. It will corrode
Question 3
A sample of water in a beaker was found to boil at 1050C at 1 atmospheric pressure. Explain this observation.
Answer
The water contained impurities which increases the boiling point
Question 4
State the mode of conduction of electricity in the following substances.
- Copper rod.
- Molten copper (II) oxide
Answer
- Delocalized electrons
- Mobile ions
Question 5
Dry ammonia was passed over heated copper (II) oxide in a combustion tube.
- State and explain the observation that was made
- Write a balanced chemical equation for the reaction above
Answer
- Black copper (II) oxide changed to brown ammonia reduces copper (II) oxide to copper.
- 3Cu0(s) + 2NH3(g) → 3Cu(s) + 3H20 + N2(g)