Activity 3.18:
Aim: To write balanced chemical equations.
Materials: Copper(II) carbonate powder, CuCO3, concentrated hydrochloric acid, HCl, concentrated ammonia solution, NH3, lead(II) nitrate solution, Pb(NO3)2, potassium iodide solution, KI and limewater
Apparatus: Test tubes, delivery tube and rubber stopper, test tube holder, Bunsen burner, 10 cm3 measuring cyclinder, test tube stoppers and glass tube
Procedure:
(A) Heating of copper(II) carbonate, CuCO3
1. Fill a spatula of copper(II) carbonate powder, CuCO3 into a test tube. Observe the colour of the powder.
2. Set up the apparatus as shown in Figure 3.18.
3. Heat copper(II) carbonate, CuCO3 and let the gas produced flow into the test tube filled with limewater. Observe the changes that take place in both test tubes.
4. When the reaction is completed, remove the test tube of limewater. Then, stop the heating.
5. Record your observations.
(B) Formation of ammonium chloride, NH4Cl
1. Using a glass tube, put 3 or 4 drops of concentrated hydrochloric acid, HCl into a test tube. Close the test tube with a stopper and leave it for a few minutes.
2. Repeat step 1 using concentrated ammonia solution, NH3 in another test tube.
3. Remove the stoppers from both test tubes. Quickly bring the mouths of both test tubes together as shown in Figure 3.19.
(C) Precipitation of lead(II) iodide, PbI2
1. Pour 2 cm3 of lead(II) nitrate solution, Pb(NO3)2 into a test tube.
2. Pour 2 cm3 of potassium iodide solution, KI into another test tube.
3. Pour potassium iodide solution, KI into lead(II) nitrate solution, Pb(NO3)2 as shown in Figure 3.20. Shake the mixture.
Discussion:
1. For each reaction in experiments A, B and C, state:
(a) The reactants and products
(b) The physical state of each reactant and product
(c) The chemical formula of each reactant and product
2. Write a balanced chemical equation for each of the reactions.
Answer:
Discussion:
1.
2. Reaction A
CuCO3(s) → CuO(s) + CO2(g)
Reaction B
HCl(g) + NH3(g) → NH4Cl(s)
Reaction C
2KI(aq) + Pb(NO3)2(aq) → 2KNO3(aq) + PbI2(s)
Aim: To write balanced chemical equations.
Materials: Copper(II) carbonate powder, CuCO3, concentrated hydrochloric acid, HCl, concentrated ammonia solution, NH3, lead(II) nitrate solution, Pb(NO3)2, potassium iodide solution, KI and limewater
Apparatus: Test tubes, delivery tube and rubber stopper, test tube holder, Bunsen burner, 10 cm3 measuring cyclinder, test tube stoppers and glass tube
Procedure:
(A) Heating of copper(II) carbonate, CuCO3
1. Fill a spatula of copper(II) carbonate powder, CuCO3 into a test tube. Observe the colour of the powder.
2. Set up the apparatus as shown in Figure 3.18.
3. Heat copper(II) carbonate, CuCO3 and let the gas produced flow into the test tube filled with limewater. Observe the changes that take place in both test tubes.
4. When the reaction is completed, remove the test tube of limewater. Then, stop the heating.
5. Record your observations.
(B) Formation of ammonium chloride, NH4Cl
1. Using a glass tube, put 3 or 4 drops of concentrated hydrochloric acid, HCl into a test tube. Close the test tube with a stopper and leave it for a few minutes.
2. Repeat step 1 using concentrated ammonia solution, NH3 in another test tube.
3. Remove the stoppers from both test tubes. Quickly bring the mouths of both test tubes together as shown in Figure 3.19.
(C) Precipitation of lead(II) iodide, PbI2
1. Pour 2 cm3 of lead(II) nitrate solution, Pb(NO3)2 into a test tube.
2. Pour 2 cm3 of potassium iodide solution, KI into another test tube.
3. Pour potassium iodide solution, KI into lead(II) nitrate solution, Pb(NO3)2 as shown in Figure 3.20. Shake the mixture.
Discussion:
1. For each reaction in experiments A, B and C, state:
(a) The reactants and products
(b) The physical state of each reactant and product
(c) The chemical formula of each reactant and product
2. Write a balanced chemical equation for each of the reactions.
Answer:
Discussion:
1.
2. Reaction A
CuCO3(s) → CuO(s) + CO2(g)
Reaction B
HCl(g) + NH3(g) → NH4Cl(s)
Reaction C
2KI(aq) + Pb(NO3)2(aq) → 2KNO3(aq) + PbI2(s)