Laboratory Activity 3A (Determining Exothermic and Endothermic Reactions):
Aim: To study the types of reactions based on heat change and the changes in thermometer readings when substances dissolve in water.
Materials: Solid sodium hydroxide, NaOH, solid anhydrous calcium chloride, CaCl2, solid ammonium nitrate, NH4NO3, solid sodium thiosulphate, Na2S2O3 and distilled water.
Apparatus: Polystyrene cups with lids, spatula, measuring cylinder and thermometer.
Procedure:
1. Measure 20 cm3 of distilled water and pour it into a polystyrene cup.
2. Put a thermometer in the polystyrene cup and leave it for two minutes. Record the initial temperature of the distilled water.
3. Add one spatula of solid sodium hydroxide, NaOH into the polystyrene cup.
4. Stir the mixture carefully with the thermometer.
5. Record the highest or the lowest temperature of the mixture.
6. Repeat steps 1 to 5 by replacing solid sodium hydroxide, NaOH with solid ammonium nitrate, NH4NO3, solid sodium thiosulphate, Na2S2O3 and solid anhydrous calcium chloride, CaCl2.
Results:
Construct a table to record your observations.
Discussion:
1. Based on your results, determine:
(a) which reaction absorbs heat.
(b) which reaction releases heat.
2. With reference to 1(a) and 1(b), classify the reactions as endothermic or exothermic reactions.
Answer:
Result:
Discussions:
1. (a) Solid ammonium nitrate, solid sodium thiosulphate, solid anhydrous calcium chloride.
(b) Solid sodium hydroxide.
2.
Aim: To study the types of reactions based on heat change and the changes in thermometer readings when substances dissolve in water.
Materials: Solid sodium hydroxide, NaOH, solid anhydrous calcium chloride, CaCl2, solid ammonium nitrate, NH4NO3, solid sodium thiosulphate, Na2S2O3 and distilled water.
Apparatus: Polystyrene cups with lids, spatula, measuring cylinder and thermometer.
Procedure:
1. Measure 20 cm3 of distilled water and pour it into a polystyrene cup.
2. Put a thermometer in the polystyrene cup and leave it for two minutes. Record the initial temperature of the distilled water.
3. Add one spatula of solid sodium hydroxide, NaOH into the polystyrene cup.
4. Stir the mixture carefully with the thermometer.
5. Record the highest or the lowest temperature of the mixture.
6. Repeat steps 1 to 5 by replacing solid sodium hydroxide, NaOH with solid ammonium nitrate, NH4NO3, solid sodium thiosulphate, Na2S2O3 and solid anhydrous calcium chloride, CaCl2.
Results:
Construct a table to record your observations.
Discussion:
1. Based on your results, determine:
(a) which reaction absorbs heat.
(b) which reaction releases heat.
2. With reference to 1(a) and 1(b), classify the reactions as endothermic or exothermic reactions.
Answer:
Result:
Discussions:
1. (a) Solid ammonium nitrate, solid sodium thiosulphate, solid anhydrous calcium chloride.
(b) Solid sodium hydroxide.
2.
