(A) Temperature remains constant during boiling of water:
Aim: To investigate whether temperature remains constant during boiling of water
Materials and apparatus: Bunsen burner, tripod stand, wire gauze, beaker, thermometer, 100 ml of water, retort stand with clamp.
Instruction
1. Pour 100 ml of water into a beaker. Record the initial temperature of water.
2. Heat the water. Record the temperature of water at 10 minutes interval until the temperature remains constant (Figure 5.15).
Questions
1. Why does the temperature of water remain constant when boiling?
2. Plot a graph of temperature against time for the boiling of water.
Answer:
(A)
1. The temperature of water is constant because the heat is used to overcome the force of attraction between the water particles.
2.
Aim: To investigate whether temperature remains constant during boiling of water
Materials and apparatus: Bunsen burner, tripod stand, wire gauze, beaker, thermometer, 100 ml of water, retort stand with clamp.
Instruction
1. Pour 100 ml of water into a beaker. Record the initial temperature of water.
2. Heat the water. Record the temperature of water at 10 minutes interval until the temperature remains constant (Figure 5.15).
Questions
1. Why does the temperature of water remain constant when boiling?
2. Plot a graph of temperature against time for the boiling of water.
Answer:
(A)
1. The temperature of water is constant because the heat is used to overcome the force of attraction between the water particles.
2.
(B) Mass remains unchanged during physical change:
Aim: To investigate whether mass remains unchanged during physical change
(I) Change in mass when ice melts into water
Materials and apparatus: Ice cubes, beaker, lever balance
Instruction
1. Weigh an empty beaker. Record the mass of the empty beaker.
2. Put ice cubes into the beaker. Record the mass of the beaker filled with ice cubes.
3. Then, let the ice cubes melt. Weigh the beaker filled with water.
4. Record the mass (Figure 5.16).
Question
1. Is there any difference between the mass of the ice cubes and water?
Answer:
(I) No
Aim: To investigate whether mass remains unchanged during physical change
(I) Change in mass when ice melts into water
Materials and apparatus: Ice cubes, beaker, lever balance
Instruction
1. Weigh an empty beaker. Record the mass of the empty beaker.
2. Put ice cubes into the beaker. Record the mass of the beaker filled with ice cubes.
3. Then, let the ice cubes melt. Weigh the beaker filled with water.
4. Record the mass (Figure 5.16).
Question
1. Is there any difference between the mass of the ice cubes and water?
Answer:
(I) No
(II) Change in mass when salt dissolves:
Materials and apparatus: Ten spatulas of fine salt, 100 ml of water, glass rod, beaker, lever balance.
Instruction
1. Weigh a beaker filled with 100 ml of water. Record the mass.
2. Put ten spatulas of fine salt into the beaker. Weigh it and record its mass.
3. Stir the water until the salt dissolves. After that, weigh the solution and record the mass (Figure 5.17).
Question
1. Is there any difference in mass before and after the salt dissolves?
Answer:
(II) No
Materials and apparatus: Ten spatulas of fine salt, 100 ml of water, glass rod, beaker, lever balance.
Instruction
1. Weigh a beaker filled with 100 ml of water. Record the mass.
2. Put ten spatulas of fine salt into the beaker. Weigh it and record its mass.
3. Stir the water until the salt dissolves. After that, weigh the solution and record the mass (Figure 5.17).
Question
1. Is there any difference in mass before and after the salt dissolves?
Answer:
(II) No
(III) Change in mass during the expansion of solid:
Materials and apparatus: Metal ball and ring, Bunsen burner, triple beam balance.
Instruction
1. Weigh a metal ball together with its ring. Record the mass.
2. Heat the metal ball for 5 minutes. Weigh the hot metal ball with its ring. Record the mass. (Figure 5.18)
Question
1. Is there any difference in the mass of the metal ball before and after heating?
Answer:
(III) No
Materials and apparatus: Metal ball and ring, Bunsen burner, triple beam balance.
Instruction
1. Weigh a metal ball together with its ring. Record the mass.
2. Heat the metal ball for 5 minutes. Weigh the hot metal ball with its ring. Record the mass. (Figure 5.18)
Question
1. Is there any difference in the mass of the metal ball before and after heating?
Answer:
(III) No