What Factors Affect the Cooling of Hot Water in a Container?

Hypothesis:

In this investigation I am going to look into the factors, which affect the heat transfer of hot water in a container.

Heat will travel from a place that is hot to somewhere where it is cold.

There are three methods of heat transfer, Conduction, Convection, and Radiation.

In conduction heat energy is past along from molecule to molecule. Molecules move more rapidly as they get hot and collide with neighbouring molecules passing along the energy. This is only possible with solids because the heat can only be conducted through molecules next to each other.

In convection hot molecules move carrying energy with them. Therefore this only works in liquids and gases. As the fluid is heated the molecules vibrate more quickly and move further apart.

In radiation heat energy passes directly by means of waves from a hot object to the cold. Therefore it is the only kind that can pass through a vacuum.

The factors, which I could investigate, are:

* Volume of water

* Surface area

* Initial temperature

* Material of container wind factor (air movement)

* Insulation type

* Size of container

* External room temperature

* Stirring or agitation

The different insulator types could affect the temperature, depending upon the what material it is so that is why we chose to investigate the factor; insulation type, to see which materials are best at keeping the water hot and which materials allow heat transfer the most. We also think that we could obtain significant and accurate results using this factor.

I think that out of all the insulating materials given, the 5cm thick foam will prove to be the best at preventing the transfer of heat. I believe this because it is quite thick and has millions of tiny holes in it, trapping in air. Rather like the way a bird fluffs out its feathers so air can get in and keep it warm. Air is a good insulator because its molecules are widely spread out and therefore it’s hard for the molecules to pass the energy onto one another. Another reason why the foam could prove to be a better insulator is because of its thickness, it can trap in much more air than a thinner material could.

Method:

Each time the experiment is performed the insulating material will be changed, but to make it a fair test, we will keep constant:

* The beaker we used

* The volume of water we used

* The temperature of the water

* The length of the experiment

* The time we measure the each of the readings

* The same liquid we’ll conduct the test with e.g. water

* The material we perform the experiment on e.g. wood.

We will use a standard glass beaker and fill it up to 200ml. The starting temperature we will use will be 80�C and we take the reading of the thermometer every 30 seconds over a 4-minute period. We will simultaneously conduct the experiment, therefore 3 results would be obtained in the same amount of time of performing one. Having three sets of results would make the results more accurate and reliable because we could see and compare them, and if one was wrong we could clearly see, also we can workout the average.

I will use the following apparatus in my experiment:

* Kettle

* Glass Beaker

* Thermometer

* Stopwatch

* Silver foil

* Cardboard

* Small bubble wrap

* Large bubble wrap

* Nylon

* Foam

* Sellotape

* Scissors

To carry out the investigation I will use the following steps:

1. Cut appropriate size of the insulating material and Sellotape all the way around the sides of the beaker. Cut an extra piece to go over the top but do not situate until step 3. (Placing the material around the sides decreases the amount of radiation, on top, reduces convection, and for conduction the science room table is made out of wood. This is a good insulator of heat so you can perform on that. Putting some of the listed insulation materials under the beaker could cause the beaker to topple over, so it would be safer and wiser to just stick with the table).

2. Boil water in the kettle and then pour the water into the beaker, and fill up to 200ml. Insert Thermometer.

3. When the temperature falls to about 82C securely fit the extra material over the top but leave room for the thermometer to stay in. (make sure you can clearly still read off the thermometer).

4. By the time you have done step 3 the temperature should have fallen to 80C. Therefore you should now begin the experiment. Start the stopwatch.

5. Every 30 seconds record the current temperature. Do this for a total of 4 minutes.

6. With the results obtained, take off the material around the beaker and pour the water down the sink.

7. Repeat these steps until you have a performed on all of the insulating materials.

To present my results I will use a table and graph of temperature and the average end temperature. I will look at my graph and by the way the results turn out, I can tell what was the most poorest and best insulator to help write in my conclusion.