Question

Q5: The following word equations represent chemical reactions.
a. Iron + Sulphur
iron sulphide
b. Ammonia + hydrogen chloride
ammonium chloride
C. copper carbonate heat
copper oxide + carbondioxide
Which word equation shows the formation of a compound from
a. Two compounds:
b. Two elements:
C. Which word equation above shows breaking of a compound into simpler
substance.
?​

Answer 1

Answer:

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Answer 2

2.       Write the balanced equation for the following chemical reactions.

           (a)  Hydrogen + Chlorine → Hydrogen chloride            (b)  Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride            (c)  Sodium + Water → Sodium hydroxide + Hydrogen

Ans: (a)  H2 (g) + Cl2 (g) → 2HCl (g)            (b)  3BaCl2 (s) + Al2(SO4)3 (s) → 3BaSO4(s) + 2AlCl3 (s)            (c)  (c) 2Na(s) + 2H2O (l) → 2NaOH (aq) + H2 (g)

3.       Write a balanced chemical equation with state symbols for the following reactions.

           (a)  Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.            (b)  Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Ans: (a)  BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)            (b)  NaOH (aq) + HCl (aq) → NaCL (aq) + H2O (l)

Page No: 10

1.       A solution of a substance ‘X’ is used for white washing.

           (a)  Name the substance ‘X’ and write its formula.            (b)  Write the reaction of the substance ‘X’ named in (a) above with water.

Ans: (a)  The substance ‘X’ is calcium oxide. Its chemical formula is CaO.            (b)  Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).                   CaO (s) + H2O (l) → Ca(OH)2 (aq)                   Calcium Oxide (Quick Lime) + Water → Calcium Hydroxide (Slaked Lime)

Page No: 13

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour of the copper sulphate solution changes.

           The reaction involved here is:            Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)

2.       Give an example of a double displacement reaction other than the one given in Activity 1.10.

Ans: 2KBr (aq) + BaI2 (aq) → 2KI (aq) + BaBr2 (aq)

3.       Identify the substances that are oxidised and the substances that are reduced in the following reactions.

           (a)  4Na (s) + O2 (g) → 2Na2O (s)            (b)  CuO (s) + H2 (g) → Cu (s) + H2O (l)

Ans: (a)  Sodium (Na) is oxidised as it gains oxygen and oxygen gets reduced.            (b)  Copper oxide (CuO) is reduced to copper (Cu) while hydrogen (H2) gets oxidised to water (H2O).

Excercise

Page No: 14

1.       Which of the statements about the reaction below are incorrect?

                2PbO (s) + C (s) → 2Pb (s) + CO2 (g)            (a)  Lead is getting reduced.            (b)  Carbon dioxide is getting oxidised.            (c)  Carbon is getting oxidised.            (d)  Lead oxide is getting reduced.

           (i)     (a) and (b)            (ii)    (a) and (c)            (iii)  (a), (b) and (c)            (iv)   all

Ans: (a)  (a) and (b)

Page No: 15

3.       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.

           (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.            (d)  Iron salt and water are produced.

Ans: (a)  Hydrogen gas and iron chloride are produced.

4.       What is a balanced chemical equation? Why should chemical equations be balanced?

Ans: A reaction which has an equal number of atoms of all the elements on both sides of the chemical equation is called a balanced chemical equation.Chemical reaction should be balanced to follow law of conservation of mass.

           (b)  2H2S (g) + 3O2 (g) → 2H2O (l) + 2SO2 (g)            (c)  3BaCl2 (aq) + Al2(SO4)3 (aq) → 2AlCl3 (aq) + 3BaSO4 (s)            (d)  2K (s) + 2H2O (l) → 2KOH (aq) + H2 (g)

6.       Balance the following chemical equations.

           (a)  HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O            (b)  NaOH + H2SO4 → Na2SO4 + H2O            (c)  NaCl + AgNO3 → AgCl + NaNO3            (d)  BaCl2 + H2SO4 → BaSO4 + HCl

Ans: (a)  2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O

           (b)  2NaOH + H2SO4 → Na2SO4 + 2H2O            (c)  NaCl + AgNO3 → AgCl + NaNO3            (d)  BaCl2 + H2SO4 → BaSO4 + 2HCl

7.       Write the balanced chemical equations for the following reactions.

           (a)  Calcium hydroxide + Carbon dioxide →nCalcium carbonate + Water            (b)  Zinc + Silver nitrate → Zinc nitrate + Silver            (c)  Aluminium + Copper chloride → Aluminium chloride + Copper            (d)  Barium chloride + Potassium sulphate →nBarium sulphate + Potassium chloride

Ans: (a)  Ca(OH)2 + CO2 → CaCO3 + H2O

           (b)  Zn + 2AgNO3 → Zn(NO3)2 + 2Ag            (c)  Al + 3CuCl2 → 2AlCl3 + 3Cu            (d)  BaCl2+ K2SO4 → BaSO4 + 2KCl

8.       Write the balanced chemical equation for the following and identify the type of reaction in each case.

           (a)  Potassium bromide (aq) + Barium iodide(aq) → Potassium iodide (aq) + Barium bromide(s)            (b)  Zinc carbonate (s) → Zinc oxide (s) + Carbon dioxide (g)            (c)  Hydrogen (g) + Chlorine (g) → Hydrogen chloride (g)            (d)  Magnesium (s) + Hydrochloric acid (aq) → Magnesium chloride(aq) + Hydrogen(g)

Ans: (a)  2KBr (aq) + BaI2 (aq) → 2KI (aq) + BaBr2 (s): Double displacement reaction

           (b)  ZnCO3 (s) → ZnO (s) + CO2 (g): Decomposition reaction            (c)  H2 (g) + Cl2 (g) → 2HCl (g): Combination reaction            (d)  Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) : Displacement Reaction