Heat Loss in Coffee.

Heat Loss in Coffee

Prediction

I predict that the best way to keep coffee warm is to have a silver insulator because of what we know on radiation and silver being a poor emitter compared to a plain beaker or a black one. I predicted this because most saucepans are silver because silver is a poor emitter compared to white and black and also silver is shiny which cuts down heat wasted by radiation.

Research

After making a cup of coffee it loses heat because of the following factor:

· Radiation

· Evaporation

· Conduction

· Convection

Radiation

The sun radiates heat through empty space in the form of tiny waves. If you absorb any of the Sun's radiation, it heats you up. This is why it is sometimes called Heat radiation. Everything gives off some heat radiation. The hotter it is the more it radiates. A black area absorbs much more radiation than a white surface. Much of the radiation that hits a white surface reflects away. A silver surface is a poor absorber and good reflector. An example of radiation is a saucepan. (A saucepan loses heat with radiation and conduction. Also it loses heat by convection by air currents rising above the saucepan.)

Evaporation

Evaporation works in a similar way to conduction. When the beaker or water is heated the molecules vibrate more at different speeds. Every so often, one molecule will gain a lot more speed than the others and will escape. When it finally escapes it all it's energy with it so less is left behind. Now that there is less energy they are cooler.

Conduction

This is the only method of heat transfer that happens in opaque solids. In the solid the particles are fixed. When heat is added they start to vibrate one by one banging into their neighbouring ...

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Evaporation

Conduction

This is the only method of heat transfer that happens in opaque solids. In the solid the particles are fixed. When heat is added they start to vibrate one by one banging into their neighbouring particle. This is how heat energy is passed on from one particle to the next. Good conductors are metals such as gold, silver and glass. A glass beaker can be safety heated on a gauze because a gauze conducts heat away from a flame.

Convection

This method of heat transfer mainly occurs in liquid and gas. In our experiment the water lost heat by convection because the hot water at the bottom density decrease so it rose to the top and cooled. The slightly cooler water descended towards the bottom creating a circulatory motion

Variables

To make the experiment a fair test the starting temperature was kept to as near as possible. We did not change the amount of water used so it would be fair.

Safety

To make sure that this experiment was safe we were careful pouring the hot water by holding the measuring cylinder with a cloth.

Observations

In this experiment we will be taking the temperature every one minute up to ten minutes. To make this a fair and accurate test we will be repeating the experiment again.

Apparatus

· 3C beaker size 250ml

· Thermometer

· Silver foil

· Black paper

· Kettle

· Sellotape

· Scissors

To Test for Radiation

Wrap the beaker in silver foil and black paper and plain and see what is the best insulator.

See what dye is the best yellow or black

Method

. Set up apparatus as shown with a thermometer inside it.

. Heat up the water and pour into the beaker.

. Quickly take the temperature every minute up to ten minutes and record in the results.

Results Table for insulators

Result table for dye

The starting temperatures are starting at different temperatures, which make the graph unfair. So I need to work out the temperature change so I can plot an accurate graph.

Conclusion

My prediction was right silver is the best insulator. I know this because at ten minutes silver has not had such a big temperature change compared to the others. We know that heat is being lost because of the graph temperature change is increasing as the time is increasing.

Evaluation

I think that during this experiment we use our apparatus accurately by having the same size beaker and measuring cylinder. I think that our experiment wasn't extremely accurate because of the cooling down at the start. This caused different starting temperature but because the table and graph recorded the change it didn't affect too much.

In my graph it shows that Silver is the best followed by black and plain last. On the other further experiment it showed that yellow dye was better than black dye. I thought that my experiment went well but that human error must have been caused because it was difficult at one time because of measuring and recording all of them at the same time this showed in my plain line where the circled point didn't fit in.

Heat Loss in Coffee.