Evaluation
I believe that the experiment was successful but there was one unreliable or slight
anomalous result, which was above the line of best fit. Also my results were way below
the lines of the results gained from the data book, the reason for this as I explained in my
conclusion that heat was lost. Overall I think my results are reliable because one it made a
straight line with all the results apart from one and two there was a increase of 240
kJmol-1 in my result but what isn't reliable about my results are that my results are lower
than the data book itself and I have explained this previously, therefore here is a problems
in my method. I also think that overall my results could support a good conclusion
because in the data book it had a difference between the points and my one did as well,
showing that as you add more carbon chains to the reaction more energy is released. But
the bad thing that wouldn't support my prediction is the values because the energy values
are too low.
The slight anomalous was butanol, which was over the line of best fit by about 75.9
kJmol-1, this means that less heat was lost or more energy of fuel was supplied to the
water, therefore a greater energy output was recorded in this experiment than it should
have been. One quite obvious reason could be that the person measuring the temperature
misread the thermometer. A second reasons for this slight anomalous result could be
because when I was measuring the distance between the wick and the copper calorimeter
the distance was closer than it should be, this will cause the wick to be closer and when I
light the wick the flame would spread out more under the base of the copper calorimeter
and cause a bigger surface area of heat to heat the water up. This could also lead to that
they'll be a smaller gap between the wick and the copper calorimeter and leading to a less
chance that heat energy will be lost. Another reason for this high value is that the wick
was out of the bottle more meaning a larger surface area of alcohol to be burnt in the air
and caused a larger flame to occur and heated the water in a very short time with only a
small amount of alcohol. More insulated material could have been used to insulate the
copper calorimeter with the glass wool, this means that heat couldn't escape easily by
conduction and a higher temperature was recorded. Another possible way that heat
couldn't escape easily was that the calorimeter had lime scale that was from other
experiments and wasn't cleaned properly. Therefore the lime scale would have acted like
an insulated inside the inner sides of the calorimeter and stopped heat from escaping by
conduction. The lime scale could have been from the water itself when the calcium
hydrogen carbonate decomposed when heated but this can't be true because the water that
was used was distilled but this could mean that the distilled water used wasn't distilled
enough. Another reason was that the water was purer than other water used in the other
experiments, this would cause the water to boil quickly than the other experiments
because the impurities in unpure water would bring the boiling point of water higher.
Therefore if it is the case that the water was pure than the other experiments it would
make us assume that less fuel of butanol was used to boil the water to a very high
temperature. There could be more oxygen in the surroundings when doing the testing for
butanol, this could of cause the alcohol to react with more oxygen faster and caused a
vigorous flame and a much bigger flame. The reaction would be faster because in order
for a reaction to start particles in the reaction must collide with each other and by
supplying more oxygen particles to the reaction they'll be a bigger chance of particles
colliding with each other and therefore increasing the rate of reaction. The temperature in
the room was hotter then usual because of the intense sunlight passing through the
window like a green house effect and causing the hot air to move quickly and react with
the alcohol quickly, causing a bigger flame that will heat the water faster. The increase in
temperature might effect the reaction rate because if we increase the temperature it can
cause the alcohol particles and oxygen particles to move quickly and to react with one
other much quickly; and also particles will have more energy to collide and cause a
harder hit to start a reaction, causing a bigger flame to heat the water. When measuring
the water the thermometer was in the hotter part of the water meaning the temperature
reading was higher than it should be.
Notice that my results are no way near the data book results and below them, this
means that massive heat lost occurred, when heat was transferred to the calorimeter and
lost trough the calorimeter or the holes in the lid. To get my results closer to the line of
the data book results I will need to make improvements or make a new method using
better equipment to obtain more reliable and accurate results that are more or less near to
the data book results. First of all I would cover the inside of the calorimeter in foil, this
will insure that heat is reflected back to the water decreasing the amount of heat lost. I
would like the base of the calorimeter to be more conductive meaning maximum heat is
transferred to the water giving us a higher energy reading. The wick should be closer to
the calorimeter so that a larger surface area is created to supply more heat to the water. A
thicker insulator should be used to keep the heat from conducting away through the
calorimeter and to stop further heat lost. A windshield should be all the way round the
fuel lamp to stop more oxygen to be blown and added to the flame, so there shouldn't be a
big flame.
For my new method I will use my preferred method because that can keep heat
loss down to a minimum. Please see Diagram 1a for setting up. This method will be
much more accurate than the old method where data logging (use of computer) is
introduced and less human errors will occur in the recording of the results. There is a
vacuum flask container to have minimum heat loss in terms of conduction. The outside
temperature is the same as the temperature in the flask so no heat would be transferred.
The base of the water container is very heat conductive (e.g. copper) to provide
maximum transfer of heat from the flame to the water. In water and other liquids when
they are heated, convection occurs and the overall temperature of water (top and bottom
of the water) in the container would be different, to counteract this we need turbines that
would constantly mix the water. Each turbine will rotate in opposite direction to keep the
heat balanced in the container. To aid the measurement of water I want the walls of the
water container to consist of thermometer cells, which will measure the overall heat of
the entire liquid. This is because it will stop the possibilities of the reduction of heat from
water to steam. This means that the temperature of the steam would be collected and this
will be part of the overall temperature of the water. All the experiments must be done in
the same fashion: the same volume and the same volume of distilled water (Using not
distilled water contain many different impurities and different concentrations of
impurities, and this will result in increasing the boiling point of the water) should be used.
The experiment should be measured for the same time and the time should be measured
with an accurate atomic clock. When time has come to measure the temperature of water,
a computer should automatically record the temperature to how many decimal places I
want, avoiding human errors when humans measure the temperature.
As my conclusion are based on a couple of results I would like to continue my
work to see if this increase of energy of 240 kJmol-1 or more, continues beyond four
carbon chains and to see if it does continue on in the alcohol series. So to do this I will
use my new method to carry on this further work and just test more alcohols. For other
further work, I would like to investigate the energy release between alkanes. This is
because alkanes have similar structures like alcohol and to see if having one atom
missing (oxygen atom) would effect the energy release value by lowering the energy
released because of missing a bond between the a atom. To do this I will need to use my
new method, which can produce better and more accurate results.
To do this I need to wear a safety goggle for safety reasons. I will use the four
first alcohol methane, ethane, propane and butane because they nearly have the same
structure of the first four alcohols and that’s what I want to compare them with. I will use
a vacuum flask container to have minimum heat loss and to stop conduction of heat
through the sides. The outside temperature must be kept the same as the temperature in
the flask, so no heat would be transferred. The water container is placed in the vacuum
container and must have a very heat conductive material (e.g. copper) base to provide
maximum transfer of heat from the flame to the water. 50ml of water will be used, as this
was the best in the preliminary experiment and using a burette to measure this water. In
water and other liquids when they are heated, convection current occurs and the overall
temperature of water (top and bottom of the water) in the container would be different, to
counteract this we need to use turbines that would constantly mix the water. And each
turbine would be put on either sides of the water container and made out of glass because
it won't melt and heat energy won't easily be stored in the glass turbine, where as metal
made ones heat would. Each turbine will rotate in opposite direction to keep the heat
balanced in the container. To aid the measurement of water I want the walls of the water
container to consist of thermometer cells, which will measure the overall heat of the
entire liquid. This is because it will stop the possibilities of the reduction of heat from
water to steam. This means that the temperature of the steam would be collected and this
will be part of the overall temperature of the water. All the experiments must be done in
the same fashion: the same volume and the same volume of distilled water (Using not
water which contain many different impurities and different concentrations of impurities,
and this will result in increasing the boiling point of the water) should be used. A fuel
lamp with a large wick should be used because we all know that alkanes are hard to light
and therefore we need to provide a larger surface area to help the ease of lighting the fuel.
The wick should be soaked in the fuel first to aid the help of lighting the fuel. The wick
should be placed right next to the base of the water container in order to spread out the
flame and to create a larger surface area and to heat the water with maximum heat
transfer. The experiment should be measured for the same time and the time should be
measured with an accurate atomic clock. When time has come to measure the
temperature of water, a computer using data logging should automatically record the
temperature to how many decimal places I want, avoiding human errors when humans
measure the temperature.