✅ 2. Required Practical: Testing Materials As Insulators (P2) Flashcards
What is the Aim of this Practical
The overall aim of this practical is to fully compare the effectiveness of different thermal insulators (tin foil, cloth, bubble wrap, cardboard) and how they affect the rate of the cooling of the water. Measurements will be taken every 30 seconds and a table of results as well as a graph can be plotted from this.
What Equipment is Needed for this Practical
Equipment:
- eye protection
- four (or the number of materials are being tested) identical containers (beakers, boiling tubes, or metal cans)
- measuring cylinder
- four (or the number of materials are being tested) thermometers
- stopwatch
- four (or the number of materials are being tested) materials to test as insulators
- elastic bands or tape
- aluminium foil or cling film (if needed for lids)
- access to hot water
- graph paper
What Method is Use for this Practical
- Set up your containers: leave one unwrapped, and wrap each of the others in a different material, using elastic bands or tape to hold the material in place. Try to make the different wrappings roughly the same thickness (tin foil, cloth, bubble wrap, cardboard)
- Prepare lids for the containers, made out of the same material as the wrapping if possible, or else made of aluminium foil or cling film.
- Make a hole in each lid which is just big enough for the thermometer to fit through.
- Use the measuring cylinder to pour equal amounts of hot water into each container.
- Put the lids onto the containers, with a thermometer fitted through each lid so that it rests near the bottom of the water.
- Start the stopwatch, and measure the starting temperature of the water.
- After 15 minutes, use the thermometer to gently stir and then measure the temperature of the water in each beaker.
Health and Safety concerns for this Practical
- Wear eye protection in case of hot water splashes
- Take care with hot water. If you need to move hot water from one place to
another, warn everyone nearby before you come through.
-Rubber bands can cause injury if launched with force. Be careful when applying the rubber band onto the glass beaker.
-Glass beakers are easily broken and can cause injuries. If there is smashed glass, carefully clean the glass up and dispose of it responsibly.
What is the Independant Variable for this Practical
The Independant Variable in this experiment is the material that is being used to insluate the beaker. This is because it is a variable that is being changed or altered throughout the experiment.
What is the Dependant Variable for this Practical
The Dependant Variable in this experiment is the Temperature of the water found inside of the smaller beaker. This is because it is the variable that is tested and measured in this experiment.
What is the Control Variable for this Practical
The Control Variables in this experiment is the time given for the water to cool down, the beaker size used to test the insluating properties, the thermometers to measure the temperature, and the size of the hole which the thermometer goes through the lid. Another important control variable is to test each material in the same room/conditions, making sure that one isn’t in a warmer or more humnid environment than other for example.
How was this Practical Made a Fair Test
There are many different considerations that needed to be taken into account when trying to achieve a fair test in this experiment. One of the main things when trying to keep your experiment as fair as possible is to make sure that you keep all of the control variables the same at all times, and at all costs.
Examples of measures that were put in place can be to give the same amount of time for each of the beakers filled with hot water to cool down, while also keeping the beakers the same size. The thermometers the same (or same type/brand), as well as the size and fit of the lid. These three things, to name a few, are vital in esnuring that this test is made fair, and that the results obtained from it are not skew or altered as a result of it. Also, each of the tests were carried out in the same room at roughly the same times, so the enviroment around each of the the beakers wouldn’t have differed a significant enough amount to affect any of the results.
How should the Results Table Be laid out
The results table was laid out with one large column dedicated to the Time (s), and another large column contained the Temperature (°C). Inside the large temperature column, you can make sub-columns of each material used to insulate the heat.
At the bottom of the table, you can also have a row of tbe Total Decrease to show how much heat was lost through each material.
How is the Chart/Graph laid out
The Chart/Graph made was a Bar Chart, with the temperature (°C) ( the dependant variable) being on the y-axis, and each material used to insulate the beaker was placed on the X-axis (as that was the independant variable).
What Conclusions can be made from this Practical
Firstly, the control beaker with no insulation lost 10°C of heat over 5 minutes. Out of the other five materials tested, the one in this experiment that showed the greatest insulating properties was actually the tin foil which only allowed the water to lose 7°C. In 2nd place was the cardboard which lost up to 9°C, the bubble wrap losing 9.5°C. The Cloth proved no better than having no insulation, losing the same amount of heat as the control experiment did, while the paper managed to lose even more (losing 11°C), however this could’ve been put down to the paper becoming soggy overtime.
How can this Practical be Improved
Overall the quality of this experiment, as well as the accuracy of the results obtained can definitly be improved by making some adjustments to the way this experiment works.
Firstly, just heating a kettle and pouring out into a beaker and then waiting for it to cool will be less accurate than a water bath with a bunsen burner to heat the water up to an exact temperature, before allowing it to cool. This would mean you have control of what temperature you start at each time, making the tests fairer, as sometimes the water would start at 75°C and others would start at 85°C, which could’ve skewed the results.
A second point is that the lid used in the experiment was of such low quality it was able to move around, and sometimes totally slip off. This would have more often than not in some of the tests, which would’ve allowed the water inside to cool quicker, which would’ve had a profound affect on the results. This is why it is important to make a lid that is as solid and airtight as possible, while using the same one for each tested material.
Lastly, sometime that might not be too viable would be to get a data logger to log the exact temperature of the water every 30 seconds (to a degree of accuracy of 2dp for example). This would not only result an more accurate readings than a human would give, but also eliminates human error in reading the thermometer.
