Quantity of heat, heat capacity Instruction card

Instructional card to the lesson

“Quantity of heat, heat capacity ”

Goals:

- explain the physical meaning of the specific heat;

- determine the amount of heat obtained or given away in the process of heat transfer, in nature, life and technology

Experimental Task

We assume that the power (energy per unit time) released during the combustion of a tablet of dry alcohol is the same for a short time. Then the amount of heat transferred to the vessel with the liquid will be directly proportional to the time during which this vessel was heated.

Group work (10 min)

Group Δt

The dependence of the amount of heat on the temperature difference

1.      Pour 100 ml of water from a glass beaker into an Erlenmeyer flask. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

2.      Measure the initial value of the temperature and put it in a notebook.

3.      Light a pill with alcohol. Wait a while for it to inflame, then place it under the ceramic grid, simultaneously switching on the timer.

4.      Stop the timer after the water temperature rises by 10° C, and remove the tablet from under the screen. Be extremely careful not to burn yourself! Put the heating time and the final temperature in the notebook. Drain the water into the sink and collect another 100 ml of water from a beaker. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

5.      Measure the initial value of the temperature and put it in a notebook.

6.      Again, place the burning tablet under the ceramic grid while simultaneously turning on the timer.

7.      Stop the timer after the water temperature rises to 20° C, and remove the tablet from under the screen. Enter the heating time and the final temperature in the notebook. Extinguish it and drain the water into the sink.

8.      Draw a conclusion on the experiment and create a poster

9.      Tell your neighbors in a circle (a trip around the world)

Group m

The dependence of the amount of heat on the mass of matter

1.      Pour 150 ml water from a glass beaker into an Erlenmeyer flask. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

2.      Measure the initial value of the temperature and put it in a notebook.

3.      Light a pill with alcohol. Wait a while for it to inflame, then place it under the ceramic grid, simultaneously switching on the timer.

4.      Stop the timer after the water temperature rises by 10° C, and remove the tablet from under the screen. Be extremely careful not to burn yourself! Put the heating time and the final temperature in the notebook. Drain the water into the sink and collect another 300 ml of water from a beaker. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

5.      Measure the initial value of the temperature and put it in a notebook.

6.      Again, place the burning tablet under the ceramic grid while simultaneously turning on the timer.

7.      Stop the timer after the water temperature rises by 10° C, and remove the tablet from under the screen. Enter the heating time and the final temperature in the notebook. Extinguish it and drain the water into the sink.

8.      Draw a conclusion on the experiment and create a poster

9.      Tell your neighbors in a circle (a trip around the world)

Group c

Dependence of the amount of heat on the type of substance

1.      Pour 150 ml water from a glass beaker into an Erlenmeyer flask. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

2.      Measure the initial value of the temperature and put it in a notebook.

3.      Light a pill with alcohol. Wait a while for it to inflame, then place it under the ceramic grid, simultaneously switching on the timer.

4.      Stop the timer after the water temperature rises by 10°C, and remove the tablet from under the screen. Be extremely careful not to burn yourself! Put the heating time and the final temperature in the notebook. Drain the water in the sink and collect 150 ml of oil from another laboratory glass. Place it on a ceramic grid by placing a thermometer in it so that the sensitive part of the thermometer is in the water but does not touch the walls of the flask.

5.      Measure the initial temperature of the oil and put it in a notebook.

6.      Again, place the burning tablet under the ceramic grid while simultaneously turning on the timer.

7.      Stop the timer after the water temperature rises by 10°C, and remove the tablet from under the screen and put it out. Enter the heating time and the final temperature in the notebook.

8.      Draw a conclusion on the experiment and create a poster

9.      Tell your neighbors in a circle (a trip around the world)

Problem Solving

First, solve easy, training tasks

1.      How much heat is needed to heat 2 kg of alcohol from 20 to 40 ˚С?

2.      Calculate the amount of heat required to heat 10 kg of water to 50°C.

3.      Calculate the amount of heat required to heat an aluminum spoon weighing 50 g from 20 to 80 ° C.

So, the easy tasks were left behind, ahead of the tasks of intermediate complexity

4.      A heated stone weighing 10 kg, being cooled in water at 1°C, transmits 4.2 kJ of energy to it. What is the specific heat capacity of the stone?

5.      How much water can be heated from 20°С to boiling, if you transfer 178.5 MJ of heat to it?

6.      How much heat is needed to heat 2 liters of water from 20°C to boiling in an aluminum pan weighing 200 g?

7.      How much heat is needed to heat a brick furnace weighing 1.5 tons from 20 to 60°C? (52.8 MJ)

Well done, you got to the difficult tasks! But we know that they will not be an obstacle on your way to achieving the goal!

8.      What is the amount of heat released during the cooling of paraffin, the volume of which is 50 liters, if the temperature has changed from 50 to 5°C?

9.      How much heat is released when the oil is cooled, the volume of which is 20 liters, if the temperature has changed from 60 to 20°C?

10.  What is the mass of a cast iron block, if during its cooling from 1115 to 15°C, 190.08 MJ of heat is released?

11.  A metal piece weighing 200 g was heated from 20 to 40°C. This required 560 joules of energy. What metal is the part made of?