The method and the results are on the changes of state lab. Do the analysis yourself first, then check the answers below.
Quick answer: Water changes state when heat is added or removed. These answers go with the grade 6 science lab on changes of state: the graph, the calculations, the uncertainties and the conclusion explained, for all 7 analysis questions.
Use the sample table to check your own readings and calculations. Notice that the plateau lasts several readings. When explaining it, always mention that the heat changes the arrangement of the particles rather than their speed.
The temperature was 0 °C from 2 min to 8 min: 8 − 2 = 6 min.
Question 2 Rate of warming
Rise = 80 − 13 = 67 °C in 24 − 12 = 12 min. 67 ÷ 12 = 5.6 °C/min (to 2 s.f.).
Question 3 Explain the flat sections
During melting and boiling, the heat is used to separate particles, not to make them move faster. The temperature stays constant until the change of state is complete.
Question 4 Boiling point reading
The thermometer may have a small calibration error (about ± 1 °C), and the air pressure may be a little lower than at sea level. Both can lower the boiling point reading.
Question 5 Why stir?
Stirring spreads the heat so the thermometer measures the temperature of the whole mixture, not hotter or colder patches. This makes readings representative.
Question 6 Use of crushed ice
Small pieces have a bigger surface area, so they melt evenly and the thermometer is surrounded by ice and water; readings are more reliable.
Question 7 Improve the lab
Take readings every minute near 0 °C and 100 °C and repeat the lab to find the mean; more data points show the plateaus more clearly.
