Task

Objective of the work

• Explain the meaning of the aggregate states of substances.
• Determine the specific heat of melting of ice.
• To be able to use the laboratory tools in the process.

Teacher’s guide

In the practical work, the students work in groups.

The students should familiarise themselves with topics such as heat/heat exchange/quantity of heat.

Before starting the practical work, familiarise and provide the students with all the necessary materials.

Give the students a worksheet to complete the lab work. You can download the worksheet from the Worksheet link:

Familiarise the students with safety procedures:

Requirements for laboratory work for the students

Laboratory works are carried out by students in the classroom under the direct supervision of the teacher and with strict adherence to safety and health requirements.

Laboratory work is accompanied by measurements and calculations. A report shall be prepared on the results of the work.

The report on the performance of laboratory work by the student shall contain:

1. The name and number of the laboratory work;
2. The name of the theme of laboratory work;
3. The purpose of laboratory work;
4. Brief description of the laboratory system (if any);
5. The methods of measurement;
6. The course of the laboratory work;
7. Results of measurements and calculations (usually in the form of tables) with obligatory indication of the units of measurement;
8. The results of the individual measurements; add a photo guide
9. The results of processing the experimental data obtained with an estimate of the error of measurements;
10. Graphs, charts, drawings;
11. Basic calculation formulas with the indication of the quantities to be measured (all the alphabetic values of the formulas must be explained);
12. Calculation and detailed analysis of the results;
13. Conclusions.

Provide this material (PBL rubrics) to students for assessment so that:

• Students understand in advance what criteria they need to prepare,
• Students will be able to assess their own peers accordingly.

Practical part of the work

Step 1: Before you begin, prepare the necessary materials

• Hot water glass no. 1
• Measuring cylinder (beaker)
• Thermometer
• Piece of ice

Step 2: First of all, measure the hot water temperature t

Hot water temperature t=32.9 ºC

Step 3: Determine the mass of hot water. To do this

• pour 1 cup of hot water into a measuring cylinder
• determine V the volume of hot water. Volume of hot water V= 24 ml = 24×10^-6 m3
• look up the density of water in the table. Water density ρ = 1000kg / m3
• calculate the mass of hot water using the formula m = ρ×V

Calculation result

Mass of hot water m = 0.024 kg

m = ρ×V = 1000 kg / m3 × 24×10^-6 m3 = 0.024 kg

Step 4: Place a piece of ice in a beaker of water and stir gently until the ice has completely melted. Then measure the temperature of the mixture in which the ice has melted.

Temperature of the mixture t=10 ºC

Step 5: Ice melting point t = 0 ºC

Step 6: Determine the mass of ice. To do this

• pour 1 cup of water into a graduated cylinder
• determine V volume of impurity water. Volume of impurity water V = 31 mL = 31×10^-6 m3.
• calculate volume of ice by subtracting volume of water from volume of mixture. V (ice) = V (mixture) – V (water)
• see the density of water in the table. Water has a density of ρ = 900 kg/m3.
• calculate the mass of ice using the formula m = ρ×V

Calculation result

V (ice) = V ( mixture) – V (water)

V (ice) = (31 – 24) ×10^-6 m3 = 7 ×10^-6 m3

m (ice) = 900 kg / m3 × 7 × 10^-6 m3 = 0.0063 kg

Ice mass m = 0.0063 kg

Step 7: Enter all results into the table

Step 8: Use the heat equation to determine the specific heat of ice melting

Q (e) – the amount of heat produced by water at 32.9°C

Q (p) – the amount of heat produced for melting ice

Step 9: Result of calculations

Specific heat of fusion of ice λ = 324400 J/kg

Step 10: Determine the absolute and relative error using the formulas below

The tabulated value for the specific heat of fusion is 340000J/kg

Δλ = 340000 – 324400 = 15600J/kg

Step 11: Draw conclusions about the laboratory work

Conclusion

In this laboratory work, the students were introduced to the aggregate states of substances. Therefore, they not only determined the specific heat of fusion of ice, but also compared it with the tabulated value and performed calculations.