Language of Chemistry Class-7 Dalal Simplified ICSE Chemistry Solutions Chapter-5

Language of Chemistry Class-7 Dalal Simplified ICSE Chemistry Solutions Chapter-5 Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-5. We Provide Step by Step Solutions of Exercise/Lesson -5  Questions and Answers of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-7.

Language of Chemistry Class-7 Dalal Simplified ICSE Chemistry Solutions Chapter-5

Board ICSE
Class 7th
Subject Chemistry
Book Name Dalal New Simplified
Chapter-5 Language of Chemistry
Unit-1 Language of Chemistry
Topic Solution of exercise questions
Session 2023-24

Exercise – 1

Language of Chemistry Class-7 Dalal Simplified ICSE Chemistry Solutions Chapter-5

Question 1. Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.

Answer 1: A reaction between matter that react together and form new products. The  substances that undergo  reaction are reactants while the new substances formed are called products.

Question 2. Represent the addition of dilute sulphuric acid to zinc by means of a chemical equation. State the function of the arrow between the reactants and products.

Answer 2:

  • Reactants

Left hand side write the reactants (substances which take part in a reaction).

  • Products

Right hand side write the products (substances formed as a result of the reaction).

Chemical equation formed is

Zn [dil.] + H2SO4→ ZnSO4 +H2[g]

The function of the arrow (→) between the reactants and products is that it represents the chemical reaction taken place between two reactants.

Question 3. A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – 

(a) colour
(b) state
(c) smell
(d) evolution of gas 
(e) formation of precipitate
(f) evolution or absorption of heat.

With reference to change of colour – state the change in colour seen when the following arc.heated – (1) copper carbonate (2) zinc carbonate (3) mercury [II]oxide (4) lead [IV] oxide.

Answer 3: Change of colour In certain chemical reactions a change of colour is seen to be observed. Heat on substances to observe change in colour of reactants and products.

On heating product formed:

  1.  CuCO3 → CuO + CO2[g]
  2.  ZnCO3 → ZnO + CO2 [g]
  3.  2HgO → 2Hg + O2 [g]
  4. 2PbO2→2PbO + O2 [g]

Change in colour:

  1. Copper carbonate is green coloured, when heated it gives out a black solid copper oxide.
  2. Zinc carbonate is white coloured, when heated it gives a yellow solid – zinc oxide
  3. Mercury [II] oxide is red, when heated it turns silvery
  4. Lead [IV] oxide is brown, when heated it turns yellow.

Question 4. Give a balanced equation for addition of iron to copper [II] sulphate solution. State the change in colour seen.

Answer 4: Copper [II] sulphate + Iron → Iron [II] sulphate + Copper

Copper [II] sulphate + Iron → Iron [II] sulphate + Copper

The colour changes from blue(CuS04) to light green(FeS04)

Question 5. In certain reactions a change of state is observed i.e. solid to liquid, liquid to gas etc. – State the change of state of the products – to give the respective reactants in each case.

 (a) C + 2S → CS2

(b) NH3 + HCl ⇌ NH4Cl

(c) 2H2  + O3 →  2H2O

(d) 2H2O →  2H2 + O2

Answer 5: (a) Carbon with sulphur

C[s] + 2S[s] → CS2[s] (carbon di sulphide)

The solid changes to a liquid state

(b) Ammonia with hydrogen chloride

NH3[g] + HCl[g] → NH4Cl[s] (ammonium chloride)

The gas changes to solid-state

(c) Hydrogen with oxygen

2H2[g] + O2[g] + 2H2O[l]

The gas changes to liquid state.

(d) Decomposition of water, water decomposes to hydrogen gas and oxygen gas

2H2O[l] → 2H2[g]  +  O2[g]

The liquid changes to gaseous state.

Question 6. In certain reactions a change of smell is observed. Give two examples from daily life of the same.

Answer 6: In certain chemical reactions – a change of smell is seen to be observed.

  1. A fresh egg gets spoiled and turns into a rotten egg, or fresh food on keeping for a long time gets spoiled. Thus a chemical change may have undergone, which many result in a change in odour [foul smell maybe Evolved].
  2. A piece of fresh bread is kept in the open for a few days. A foul smell maybe observed along with growth of fungus, after keeping the bread for a prolonged time.

Question 7. In certain reactions an insoluble solid called precipitate is formed. State the colour and name of the precipitate formed in each of the following reactions involving addition of:

(a) Dilute hydrochloric acid to silver nitrate.
(b) Iron [II] sulphate to sodium hydroxide.
(c) Iron [III] chloride to ammonium hydroxide.
(d) Copper [II] sulphate to sodium hydroxide.
(e) Lead nitrate to ammonium hydroxide.?

Answer 7: (a) Dilute hydrochloric acid to silver nitrate.

In the reaction of Silver nitrate and dil. hydrochloric acid

AgNO3 + HCl → HNO3 + AGCl↓ (silver chloride)

The precipitate formed is Silver Chloride which is milky white in colour.

(b) Iron [II] sulphate to sodium hydroxide.

Iron [II] sulphate and sodium hydroxide

FeSO3 + 2NaOH → Na2SO4 + Fe(OH)2↓ (Iron [II] hydroxide)

The precipitate formed is Iron [II] hydroxide which is dirty green in colour.