Resistance
Safety - must always wear safety glasses and we should be very careful
not to
drop any acid. Fair test- we must make sure that we use the same size,
amount
and roughly the same mass of chips, this is because we want to keep
the chips
roughly the same all the way through the experiment so that it will
be a fair
test and the results we be in relation to each other, otherwise the
results will
be completely different to what we will expect and it will ruin
the experiment.
We must also take our readings at the same intervals
throughout the experiment
i.e. I will take a reading every fifteen seconds
for all of my experiments. I
predict that the more concentrated the acid the
quicker the reaction will take
place, because the more concentrated the acid
is then it will make the chips
react faster and more hydrogen will be given
off in a quicker time. The smaller
the stones are, the even quicker the
reaction will happen, this is because the
acid has a smaller surface area to
act upon. Equipment- We will need a boiling
tube, calcium carbonate chips,
hydrochloric acid, water, a stop watch, a gas
syringe and a bung on the top
of the boiling tube with a delivery tube connected
to the gas syringe. I will
also need a stand and a clamp to hold on to the
syringe. Method When doing my
experiments I will use the same procedure
throughout. Once I have set up the
apparatus I will measure out 5cm3 of acid in
a measuring tube and then pour
it into a boiling tube. Then I will be ready with
the stop watch and then
quickly drop in the chips into the acid, push on the
bung and and start the
stop watch. This must all be done in a very short space
of time. From there,
I must take the reading from the volume in the gas syringe
every fifteen
seconds very accurately until it reading is not changing very
much. I must
record the results in a table and then write it up neat later. The
factors
which may affect how well the experiment works are how quickly the chips
are
put in and then the bungplaced on and the stop watch pressed. Although
this
is a factor it is not really a major factor that will affect the end
results,
and as long as the time it all takes is kept constant throughout
then it should
not matter too much. Other factors are what kind of water to
use for dilution, I
could either use water from the tap which is not very
pure or it may be too hot
or too cold, or I could use distilled water. Tap
water may have some things in
it which may affect the results. The
temperature also could affect the
experiment because if heat is applied then
the particles would move around more
and affect the results , and then more
gas would be made. I think I will need
one result for each concentration and
later if I need to repeat any experiments
I can do. To get the best
results I need to use the equipment in the best
possible way. Some ways of
doing this would be to twist the gas syringe back and
forth so as to not get
the syringe stuck, which could affect our results.
Another thing would be
to sieve the chips so to get the best marbles we can. An
important point is
that I must get the right amount of acid and the best size
and amount of
marbles, because if for 4mol if I used about 4 chips then too much
gas will
be produced and the syringe will go over the 100 mm3 area in the
syringe in a
very quick time, and so we will not be able to take correct
readings. So to
over come this problem we will test to see how many chips and at
what size
will be the best to use. This is where my trialexperiments, that I did
before
I started, came in handy because it allowed me to know what amount and
size
of chips to use. After doing my trial experiments I worked out that 1
medium
sized chip around 0.63g would be best to use. But I must remember that
if
I use 1 chip then I must use 1 chip roughly the same size all the way
through on
all the different concentrations. We also did an experiment before
to give us an
idea as to what to do. It was the reaction between Magnesium
and hydrochloric
acid. This was a very good thing to do because it showed us
how to use the
equipment and an idea as to what was to come. I have used a
few books to help me
with my project, I have used my note book and my GCSE
Chemistry Gallagher and
Ingram text book where I got a good amount of
information. Evaluating Evidence I
think that the experiment went very well.
This is because I got all the results
that I wanted and they look very good.
The results were very accurate and so I
am able to make a good conclusion.
From looking at my results I can see that
there were no poor results which
was a good thing and it proves that everything
went very well. Even though
the experiments went very well I decided to repeat
one concentration of acid
twice just to see if I could repeat the experiment and
get roughly the same
results, which is what I did do, and these to went very
well. There was no
real source of error in the apparatus along as it all was
working well and
the way it should of been. The only possibility was if the
temperature of the
acid had changed from when we did the first reading to the
finish i.e from
when we did the first experiment, the acid hopefully would have
been the same
temperature. From looking at my results and graph I am able to
conclude that
the more concentrated the acid the quicker the reaction happened
and the more
gas was produced. As we look at the graph we can clearly see that
in all five
results at the beginning the reaction happened more quickly than at
the end
where we can see that it started to tail off. Before I did the
experiments I
made some predictions they were that the more concentrated the
acid was the
quicker the reaction [1]would happen and more hydrogen would be
produced.
This was completely correct because what I thought would happen did.
At
this point we are able to answer our main hypothesis which was how
does
changing the concentration of acid affect the rate of reaction
between
hydrochloric acid and calcium carbonate. The answer to this would be
that
changing the concentration of the acid will either make it go slower or
quicker
and more or less gas would be produced depending on whether the
concentrations
were more or
less.