CBSE Class 10 Science 2019 · Paper 31/5/1 · Question 8(b)
You might have noted that when copper powder is heated in a china dish, the reddish brown surface of copper powder becomes coated with a black substance.
- (a)Why has this black substance formed ?
- (b)What is this black substance ?
- (c)Write the chemical equation of the reaction that takes place.
- (d)How can the black coating on the surface be turned reddish brown ?
Answer
Heated copper combines with oxygen to form black copper(II) oxide; passing hydrogen over it reduces it back to reddish-brown copper.
(a) On heating, copper combines with the oxygen of the air: the copper is oxidised, and the oxide formed coats its surface.
(b) Copper(II) oxide, .
(c)
(d) By passing hydrogen gas over the heated black coating: . The copper(II) oxide is reduced back to reddish-brown copper.
🔒 Step-by-step solution
Sign up free to see every step of how it is worked out.
From the board papers
More questions from Chemical Reactions and Equations
Class 10 Science — every question with an expert-verified, step-by-step solution.
- Q1 Which of the statements about the reaction below are incorrect? 2P…
- Q1 Why should a magnesium ribbon be cleaned before burning in air?
- Q2 Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above reaction is an example of a
- Q2 Write the balanced equation for the following chemical reactions.…
- Q3 What happens when dilute hydrochloric acid is added to iron filli…
- Q3 Write a balanced chemical equation with state symbols for the follow…
- Q4 What is a balanced chemical equation? Why should chemical equati…
- Q5 Translate the following statements into chemical equations and then…
- Q6 Balance the following chemical equations. (a) HNO₃ + Ca(OH)₂ → Ca(N…
- Q7 Write the balanced chemical equations for the following reactions. (…
- Q8 Write the balanced chemical equation for the following and identify…
- Q9 What does one mean by exothermic and endothermic reactions? Give…
All 298 questions on Chemical Reactions and Equations → Browse all Science chapters →