investigation SA:VOL ratio Flashcards
state your hypothesis
If the surface area to volume ratio (1000ml beaker) is larger then the temperature will decrease at a faster rate.
list your variables
Independent: the size of the beaker
Dependent: change in temperature of the water in the different beakers over 30 minuets
Controlled:
volume of water in each beaker, collecting data from the same starting temp, length of time experiment is run for,
Uncontrolled variables: human errors, environmental factors such as humidity.
discuss the reliability of your experiment
The experiment is reliable as there were 5 trials done of both the 100ml beaker and 100ml beaker which show a consistently similar results besides from test 5 for the 100ml beaker where the temperature for each minuet was consistently 2-3 degrees off the average and the others we not.
most variables were cotrolled but further discussed in validity of experiment
discuss the validity of the experiment
Our experiment did test how surface area effects heat loss we ensured this by controlling the time at which each temperature was taken by using the data logger equiptment and finishing our experiment at the same 30 min mark, the volume of water in each beaker by using a measuring cylinder and keeping all experiments in the same room so that the temperature gradient for all experiments are similar and wont effect the rate of heat transfer.
Some variables that we could not control was the humidity of the room this would affect the rate at which heat is transferred through evaporation. We did not set anyrules on touching the beakers as if anyone touched the beaker the heat could’ve also been transferred through conduction. The age or wear of the temperature recording devices may have effected the accuracy This effecting the validity of the experiment.
evaluate your experiment explaining any experimental errors and factors that could increase validity or reliablity
this includes factors that could have increased reliablity and validity of the experiment by further controlling more variables.
- There was no control group for this experiment.
- If all the beakers were kept in the same exact temperature this may have increased the reliability as more variables would’ve been controlled
- Increase samples sizes of beakers ; 100,300 500,800,1000 to increase the reliability
- Have a longer time span for the experiment
- Human errors such as not level with the measurement scale leading to inaccurate readings
- Calibrating the thermometers prior to the experiment to check theyre accurate.
conclusion
The results support My hypothesis as I states that if the surface area to volume ratio of the shape increases (1000ml beaker) then the rate the heat is lost at increases. and as the 1000ml beaker had a ratio of 2:1 and the 100ml beaker had a ratio of 1:1 the 100ml had the larger SA: volume ratio meaning it lost heat at a faster rate as seen in the following results at the 2 minuet mark, half way point , and at the end the 1000ml beaker was 6.78, 9.24, 7.4 degrees below that of the 100ml beaker.
what is validity
Validity refers to how accurately a method measures what it is intended to measure.
discuss the data and provide a scientific explaination
The surface area to volume ratio does affect the amount of heat loss for each beaker.
there was a clear relationship between the surface area and the rate at which heat was lost. The 1000ml beaker had a larger SA therefore lost heat at a faster rate. As seen on the graph both beakers started at a similar temperature (66 degrees). The 1000ml beaker in the first 2 minutes the temperature had dropped by 6.78 degrees and the 100ml beaker temp dropped by 3.88 degrees. At the half way mark (15 minuets) the 1000ml beaker was at 37.1 degrees the 100ml beaker was at 46.44 degrees, meaning there’s a difference of 9.34 degrees. At the end of the experiment 30 minuets, the temperature of the 1000ml beaker was 29.58 and the temperature for the 100ml beaker was 36.98 which is a 7.4 degree difference
As heat is lost at a set rate per unit of area regardless of volume, hence the beaker with the larger SA will lose a greater proportion of heat or faster than a beaker with a smaller SA. There is also more exposed area where heat can escape and be transferred via radiation. Therefore explaining why the 1000ml beaker dropped by a larger amount then the 100ml beaker at 2 minuets. The same reason remains for the 15-minuet mark where the 1000ml beaker was 9.34 degrees lower then that of the 100ml beaker. And finally at the end of the experiment at 30 mins the 1000ml beaker was 7.4 degrees cooler.
