Advertisements
Advertisements
प्रश्न
You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2 and water. In which of the above containers, can these solutions be kept?
Advertisements
उत्तर
- Solutions to be kept in a copper container:
- Dilute HCl can be kept since no chemical reaction is expected. Copper is placed below hydrogen in the activity series.
- Dilute HNO3 cannot be kept since a chemical reaction is expected. Nitric acid is a strong oxidising agent.
\[\ce{3Cu_{(s)} + 8HNO_3_{(dil)} -> 3Cu(NO3)2_{(aq)} + 2NO_{(g)} + 4H2O_{(aq)}}\] - ZnCl2 solution can be kept since copper is placed below zinc in the activity series and no chemical reaction is possible.
- Water can be kept since no chemical reaction is expected.
- Solutions to be kept in an aluminium container:
- Dilute HCl cannot be kept since aluminium reacts with acid to evolve hydrogen gas.
\[\ce{2Al_{(s)} + 6HCl_{(aq)} -> 2AlCl3_{(aq)} + 3H2_{(g)}}\] - Dilute HNO3 can be kept. Actually, aluminium is initially oxidised by the acid to aluminium oxide (Al2O3). A coating of aluminium oxide gets deposited on the surface of the metal and makes it passive towards reaction with the acid.
- ZnCl2 solution cannot be kept since a chemical reaction will take place as aluminium is placed above zinc in the activity series.
\[\ce{2Al_{(s)} + 3ZnCl2_{(aq)} -> 2AlCl3_{(aq)} + 3Zn_{(s)}}\] - You can store water as such in the container. However, we cannot keep steam since a chemical reaction is likely to take place.
\[\ce{2Al_{(s)} + 3H2O_{(g)} -> Al2O3_{(s)} + 3H2_{(g)}}\]
- Dilute HCl cannot be kept since aluminium reacts with acid to evolve hydrogen gas.
APPEARS IN
संबंधित प्रश्न
Which of the statements about the reaction below are incorrect?
\[\ce{2PbO(s) + C(s) → 2Pb(s) + CO2(g)}\]
- Lead is getting reduced.
- Carbon dioxide is getting oxidised.
- Carbon is getting oxidised.
- Lead oxide is getting reduced.
What are anti-oxidants? Why are they added to fat and oil containing foods?
When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of:
(a) Cl2
(b) H2
(c) N2
(d) O2
The electron releasing tendency of zinc is ______ than that of copper.
Identify from the reaction the reactants that undergo oxidation and reduction.
2Mg + O2 → 2MgO
Explain the following in term of gain or loss of oxygen with two examples.
Oxidation
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
H2S + Cl2→ 2HCl + S
Name:
a liquid that is an oxidizing agent as well as a reducing agent.
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
State what is reducing agent. Give an example of oxidising agent in the gaseous, liquid, and solid form.
Identify the oxidising agent (oxidant) in the following reactions
`"CuSO"_4 + "Zn" -> "Cu" + "ZnSO"_4`
Identify the oxidising agent (oxidant) in the following reactions
`"V"_2"O"_5 + 5"Ca" -> 2"V" + 5"CaO"`
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?
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The temperature of the reaction mixture rises when aluminium (Al) is added.
Explain this observation giving suitable reason.
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The reaction of sodium metal is found to be highly explosive
Explain this observation giving suitable reason.
On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained :
- Write a balanced chemical equation for the reaction involved.
- What other name can be given to this precipitation reaction?
- On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
Answer the questions based on the equation below:
\[\ce{CH3 - CH2 - OH ->[{[O]}][K2Cr2O7/H2SO4] CH3 - COOH}\]
- What type of reaction is it?
- What is the role of the chemical written on the arrow?
- Give one example of one such type of chemical as in answer (b).
In the redox reaction:
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
State the change in colour observed in following case mentioning the reason:
Copper powder is strongly heated in air.
