Date: 5.12.11 Lab# Page# TITLE: Changes of state. AIM: To observe how temperature affects the changes of state of water. APPARATUS:

• Stopwatch. • Thermometer. • Boiling tube. • 30g of ice. • Bunsen burner. • Retort stand and clamp. • Beaker and water bath. • Tripod stand

METHOD / PROCEDURE: 1. 30g of ice was placed inside a boiling tube. 2. A thermometer was then put into the ice in the boiling tube and the

stopwatch started. The reading on the thermometer was also recorded. 3. The ice was observed until all of the ice melted. The time at which all the

ice melted was recorded and the temperature on the thermometer was also recorded.

4. The stopwatch was paused and the boiling tube was placed into a water bath with the aid of a retort stand and clamp as shown in the diagram below. The stopwatch was then started again.

5. The temperature of the water in the boiling tube was then recorded at one minute intervals until the water completely boiled off.

6. A graph of temperature versus time was then plotted using the results obtained.

DIAGRAM SHOWING THE SETUP OF APPARATUS: Draw a large, clearly labeled diagram as shown below.

RESULTS AND OBSERVATIONS: Table showing readings for temperature, time and observations.

Time / Minutes Temperature / °C Observations 1 0 Ice begins to melt 3 0 5 1 Temperature was constant until all the ice

melted 6 8 7 16 8 25 9 32 10 42 11 50

12 58 13 64 14 74 15 83

16 92 17 100 Water begins to boil. Steam given off. 20 100 25 100 Temperature remained constant until all the

water boiled off.

GRAPH: Graph plotting temperature /°C against time /minutes. Use the results in the table to plot a graph with temperature on the y-axis and time on the x-axis. Draw the best straight line joining all the points. The graph should look like the one shown below.

DISCUSSION: Answer the following questions. 1. What are the three states of matter? 2. What is the process by which a solid turns to a liquid? 3. At what temperature did the ice begin to melt? 4. What do you notice about the temperature reading from the period of time when

the ice starts to melt to when all the ice melted? 5. What is the process by which a liquid turns to a gas on heating? 6. At what temperature did the water begin to boil? 7. What do you notice about the temperature reading from the period of time when

the water starts to boil to when all the water boiled off? 8. Describe the shape of the graph from the point at which all the ice melts until the

point at which the water starts to boil. Answers:

1. The three states of matter are solids, liquids and gases. 2. The process by which a solid turns into a liquid is called melting. 3. In the experiment the ice started melting at 0°C. 4. While the ice melted the temperature remained constant until all of the ice totally

melted. This is shown as a plateau on the graph. 5. The process by which a liquid turns to a gas on heating is called boiling. 6. Water started boiling at approximately 100°C. 7. The temperature remained constant until all of the water boiled off. 8. On the graph the point between the melting of the ice and the boiling of the water

is represented by a sloping, diagonal straight line. This line suggests that temperature increased linearly with time.

CONCLUSION: When heat is applied to water, the temperature of the water rises. However, at the points at which ice melts and water boils, the temperature remains constant. Thus, the temperature of a substance remains steady during a change of state, despite the addition of heat energy.