Advertisements
Advertisements
Question
State the change in colour observed in following case mentioning the reason:
Copper powder is strongly heated in air.
Advertisements
Solution
Copper powder turns from brown to black when heated vigorously in the presence of oxygen because oxygen reacts with copper powder to form copper oxide, which has a dark colour. Thus, the appearance of copper oxide is what causes the colour change.
\[\ce{2Cu(brown) +O2 ->2CuO(black)}\]
APPEARS IN
RELATED QUESTIONS
Why is photosynthesis considered an endothermic reaction?
Is oxidation an exothermic or an endothermic reaction?
Fill in the blank
In redox reaction oxidation and reduction occur ............................
Indicate which of the following statement is true and which is false:
The removal of hydrogen from a substance is called reduction.
Name:
an oxidizing agent that does not contain oxygen.
Which among the following are physical or chemical change?
Evaporation of petrol
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
Silver metal does not show any change
Explain this observation giving suitable reason.
The formation of brown colour on the freshly unit surface of vegetables and fruits is because ______ of organic compounds present in them.
______ is a metal that has a high resistance to corrosion.
When hydrogen gas is passed over black copper oxide, a reddish-coloured layer of copper is formed.
Answer the questions that follow based on this reaction.
- Write the equation.
- What type of reaction is it?
- Complete the blanks:
In this reaction, an oxygen atom goes away from CuO (copper oxide), which means that ______ of copper oxide takes place, whereas a hydrogen molecule takes up an oxygen atom and water (H2O) is formed, meaning ______ of hydrogen takes place.
