Q.1. (i) How is ammonia collected? Why is ammonia not
collected over water ?
(ii) Which compound is normally used as a drying agent for ammonia ?
Solution:
(i) (a) Ammonia gas is lighter than
air and hence collected by the downward displacement
of air.[V.D. of NH3 = 8.5, V.D. of air =
14.4]
(b) Ammonia is not collected over water since it is highly soluble in water.
[1 vol. of water dissolves about 702
vol. at 20 ºC and 1 atmos. pressure].
(ii) Quicklime [CaO]. (iii) Quicklime [CaO].
Q.2. (i) What is the purpose of Haber’s Process.
(ii) Name the gaseous inputs of the Haber’s process and
state the ratio by volume in which the gases are mixed.
(iii) What is done to increase the rate of the reaction
in the Haber’s Process.
(iv) Give two different ways by which the product can
be separated from the reactant.
(v) Write the equation for the reaction in the Haber’s
Process that forms ammonia.
(vi) State the purpose of liquefying the ammonia
produced in the process.
Solution:
(i) Manufacture of Ammonia.
(ii) Nitrogen [N2] and Hydrogen [H2] in the ratio 1:3 by volume.
(iii) Temperature is kept low and pressure high.
(iv) (a) Liquefaction – Ammonia is
easily liquefied and hence separated from nitrogen and
hydrogen. (b) Dissolving in water
– Ammonia is highly soluble in water and hence
separated from nitrogen and hydrogen.
(v) N2 + 3H2 → 2NH3 + Δ.
(vi) Ammonia is easily liquefied while nitrogen and hydrogen
are not easily separated. Hence ammonia is separated from nitrogen and
hydrogen.
(vii) N2 + 3H2 → 2
NH3 + Δ.
Ratio of nitrogen and hydrogen is taken as 1:3. Temperature is
kept 450-500ºC and pressure at 200 to 900 atmos. Catalyst
iron with promoter molybdenum is used.
Q.3. (i) Write equation for the following:
(a) Burning of ammonia in oxygen (b) Catlytic oxidation
of ammonia. What do you observe in (a)? Name the catalyst
used in (b). In the reaction referred to in (b), the catalyst glows red hot. Why? What is the name of the industrial process which starts with the
reaction referred to in .
Solution:
(i) (a) 4NH3 + 3O2 → 2N2 + 6H2O.
Pt
(b) 4NH3 + 5O2 → 4NO + 6H2O + Δ .
800ºC
(b) 4NH3 + 5O2 → 4NO + 6H2O + Δ .
800ºC
Observation – Dry ammonia does not burn when passed through ignited tube. When ammonia is
passed through ignited tube with a passage of oxygen,
ammonia burns with a greenish yellow flame forming
nitrogen and water.
Catalyst – Catalyst used is Platinum.
The catalyst glows since the catalytic oxidation of
ammonia is an exothermic reaction.
The industrial process is known as ‘Ostwald’s Process’ for the manufacture of Nitric Acid.
The industrial process is known as ‘Ostwald’s Process’ for the manufacture of Nitric Acid.
Q.4. (i) Name a simple method you would employ to
prepare ammonium salts in your laboratory.
(ii) What property of ammonia is demonstrated by the
Fountain Experiment. Write the balanced equation for the reaction between
ammonia and sulphuric acid.
(iii) Choose the correct word from the brackets for
each sentence and write a balanced equation for the same.
(a) Ammonium chloride is a soluble salt prepared by
______ (precipitation, neutralization).
(b) When ammonium chloride is heated, it undergoes
thermal ______ (decomposition / dissociation).
(iv) Name a gas whose solution in water is alkaline.
(v) Name the ion other than ammonium ion formed when
ammonia dissolves in water.
(vi) Select the correct compound from the list given –
Ammonia, Copper oxide, Copper sulphate,
Hydrogen chloride, Hydrogen sulphide, Lead bromide – which matches the
description given below:
Although this compound is not a metal hydroxide, its
aqueous solution is alkaline in nature.
Solution:
(i) Neutralization : Ammonia in the gaseous form or in aqueous solution [NH4OH] neutralizes acids forming the
respective ammonium salts.
(ii) Fountain Experiment demonstrate
the high solubility of ammonia gas in water.
2NH3 + H2SO4 → (NH4)2SO4.
(iii)(a) neutralization.
NH4OH + HCl → NH4Cl + H2O
(b) dissociation.
(iv) Ammonia.
(v) Hydroxyl ion [OH– ]
(vi) Ammonia
Q.5. (i) Write the equation for the
reaction of hydrochloric acid with manganese (IV) oxide.
(ii)Name the lead compound that can
be used to oxidize hydrogen chloride to chlorine.
(iii) Manganese (IV) oxide, lead
(IV) oxide and red lead [Pb3O4] react with conc. HCl
liberating chlorine. (a) What is the common property being shown by these metal
oxides. (b) Write the equation for the reaction of conc. HCl with Pb3O4.
(iv) Write balanced equations for
the reaction of manganese (IV) oxide and concentrated hydrochloric acid.
(v) Select the correct compound from
the list – Ammonia, Copper oxide, Copper sulphate, Hydrogen chloride, Hydrogen
sulphide, Lead bromide – which matches with the description given below : This
compound can be oxidized to chlorine.
Solution:
(i) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2.
(ii) Lead dioxide (PbO2) and Red lead (Pb3O4).
(iii) (a) They are oxidizing agent.
(b) Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2
↑
(iv) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2.
(v) Hydrogen chloride.
.
Q6. Hydrogen chloride dissolves in water forming an acidic solution. Give three distinct tests [apart from using an indicator] you would carry out with this solution to illustrate the typical properties of an acid.
Q6. Hydrogen chloride dissolves in water forming an acidic solution. Give three distinct tests [apart from using an indicator] you would carry out with this solution to illustrate the typical properties of an acid.
(ii) (a) Hydrochloric acid reacts
with active metals to liberate a colourless and odourless gas which burns with
a popping sound liberating hydrogen gas.
Mg + 2HCl
(dil.) → MgCl2 + H2.
(b) Dilute hydrochloric acid reacts
with metallic carbonate and bicarbonate to liberate a colourless and odourless
gas with brisk effervescence which turns lime water milky i.e. CO2.
Na2CO3 + 2HCl
(dil.) → 2NaCl + H2O + CO2
Confirmatory test :
Ca(OH)2 + CO2 → CaCO3 + H2O.
(c) Dilute hydrochloric acid reacts
with metallic sulphite and bisulphate to liberate a colourless gas having smell
of burning Sulphur which turns acidified potassium dichromate paper from orange
to green and potassium permanganate solution from purple to colourless.
Na2SO3 + 2HCl
(dil.) → 2NaCl + H2O + SO2
Q7. Write the equation for the equation for the
reaction of hydrochloric acid with lead nitrate solution.
Sol.
When dilute HCl is added to lead
nitrate solution a white precipitate soluble in hot water but insoluble in cold
water is formed.
Pb(NO3)2
+ 2HCl → PbCl2 ↓ + 2HNO3.
(Q8) Write balanced chemical
equation for the reaction of dilute hydrochloric acid with (a) copper oxide (b)
zinc (c) calcium bicarbonate.
Sol. (iv) (a) CuO + 2HCl → CuCl2 + H2O
(b) Zn + 2HCl → ZnCl2 + H2
(c) Ca(HCO3)2 + 2HCl → CaCl2 + 2H2O + 2CO2.
Q.9. What must be added to sodium chloride to
obtain hydrogen chloride. Write the equation for the reaction.
Solution:
(i) Concentrated sulphuric acid.
NaCl + H2SO4 (Conc.)
→ NaHSO4 + HCl ↑
2NaCl + H2SO4 (Conc.) → Na2SO4 + 2HCl ↑
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