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
When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
Hydrogen burns with a ______ flame and ______ sound is heard.
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Pb2+→ Pb + Zn 2+
Divide the above equation into oxidation and reduction half-reactions.
Choose terms from the options given in brackets to complete this sentence.
When CuO reacts with hydrogen,………………… is reduced and ……………….is oxidized to ………………….
(CuO, H2, Cu, H2O)
Name:
a liquid that is an oxidizing agent as well as a reducing agent.
Complete and balance the following equation:
CuO +__________→ Cu +___________
Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment? Is it a chemical or a physical change?
Which among the following are physical or chemical change?
Heating of an iron rod to red hot
