This investigation is aiming to show how the volume of water effects the rate of cooling,

Evaluation

The sources of error which make the results inaccurate in this whole experiment is firstly trying to keep all the starting temperatures exactly the same. As if you take the water the out the kettle, which increases the water's temp to 70ºC, then there would be temperature drops in the time of pouring the water into a beaker, into a measuring cylinder then into the test tube. And the resulting temperature might be more or less but if it's less then it has to be restarted, which wastes time. And if it's more then you have to wait till it goes down to that same temperature. Human error can creep into this so the starting temperature isn't the same which affects the outcomes of the results not being accurate. Additionally I think trying to keep the environmental temperature the same to not affect the results is harder especially if it's needed to be done over two weeks. As that is something we cannot control and it changes by itself, this is a source of error as it affects the cooling rate when it changes. Lastly human error again can creep in leaving the measured temperatures inaccurate or even in the volumes, it can affect the volume of water making it incorrect to what it should be, and this leaves the end results inaccurate.

If I could complete this investigation again the improvements I would perform to it are doing it all in one day so temperature over days can't affect it. But the temperature may change within the one day as it changes from time to time aswell as day to day, so I would place it somewhere where the temperature is the same so it doesn't affect the end results, that place can only be a water bath. Also I would make sure the results are more accurate by stopping the stopwatch at exactly 5 mins, and if need be put it in decimals and double checking the temperature of the water.

BIOLOGY PLAN-Investigating the volume of water to the rate of cooling

Introduction

This investigation is aiming to show how the volume of water effects the rate of cooling, so that it can be concluded what factor of the water is effecting the rate of cooling. The volume of water is the independent variable as that is being controlled by me, the dependent variable is the rate of the cooling of the water as the outcome of it depends on the volume of water and this variable is being measured.

Method

The apparatus was setup as firstly 40cm3 of water was taken, measured by a measuring cylinder, and poured into a beaker, this was kept at a temperature of 50ºC, using a thermometer, and it was then poured into a test tube. Straight after the thermometer was put into the test tube and the stopwatch was started for measuring the temperature, and at regular intervals of 1min the temperature was measured and noted until 5mins. This was repeated for 6 more experiments where after each experiment the water was decreased by 5cm3 but kept at 53ºC. And lastly the surface area: volume ratio was noted by seeing whether it was higher or lower than it's previous volume.

Prediction

I think the higher the volume the lower the rate of cooling, so it takes longer for heat to be lost when there's a higher volume. The simple answer to me thinking this is that when there's a higher volume there are more particles, so if there are more particles at the same temperature it will take longer for all those particles to cool down. The more advanced answer is that when the particles have heat they speed up using up the heat energy, so it makes them slow down and lose the heat. Because heat always goes from hot to cold the heat in the water will go into the environment as it is colder than the water. Also I think surface area: volume affects the cooling rate, because the SA:V( where V is already bigger than SA) is getting further away as the volume increases, so it increases faster than the surface area. And when the SA:V is further away this means there's a lower cooling rate because there are more particles in more volume and the heat can only escape from the open top. And because there's a higher volume there are more particles and distance where when the particles speed up they use up the heat. This heat travels to that distance, max, breaking the bonds and then traveling into the environment so it takes longer so has a lower cooling rate.

Variable Table

Variable

Type

How change/measure/control

Volume of Water

Independent

The volume of water will be changed in each experiment from 40cm3 to 10cm3 in 5cm3 steps. This will be measured each time by a measuring cylinder and it will change the cooling rate of the water.

Cooling Rate of Water

dependent

The outcome of this depends on the volume of the water and this will be measured every minute for 5 mins. The cooling rate is found by Temp change/Time taken.

Environmental Temperature

Controlled

It will be done at room temp about 20º C, and this won't change dramatically but it can affect the accuracy of the results.

Starting Temperature of Water

Controlled

In all 7 experiments I will make sure the starting temperature is 53ºC each time. This will be measured by a thermometer and it will be controlled and not change to make sure it won't affect the accuracy of the cooling rates.

Insulation

Controlled

Each time the experiment's completed it will be made sure no insulation is around the test tube other than the air around it, because this will affect the results and then it can't be concluded what from the volume of water affects the cooling rate.

Surface area: volume

dependent

this will be measured each time the volume of water changes, as it depends on that.And it will be measured as being higher or lower than it's previous volume