(cm3 ) ?Time (seconds) Vol. of gas produced.
(cm3 ) ?0 ?????????? 0 ??????????? 0???? ?????????? 0 ???????????? 0 ????????? 0 10 ?????????? 7 ?????????? 10 ?????????? 9 ??????????? 10 ????????? 8 20 ????????? 12 ?????????? 20 ????????? 14 ??????????? 20 ???????? 13 30 ????????? 19 ?????????? 30 ????????? 22 ??????????? 30 ???????? 21 40 ????????? 26 ?????????? 40 ????????? 30 ??????????? 40 ???????? 28 50 ????????? 36 ?????????? 50 ????????? 37 ??????????? 50 ??????? 36.5 60 ????????? 48 ?????????? 60 ????????? 50 ??????????? 60 ???????? 49 70 ????????? 57 ?????????? 70 ????????? 58 ??????????? 70 ??????? 57.5 80 ????????? 68 ?????????? 80 ????????? 64 ??????????? 80 ??????? 65.5 90 ????????? 76 ?????????? 90 ??????? ??79 ??????????? 90 ???????? 78 ???????????? 100 ????????? 90 ????????? 100 ????????? 90 ?????????? 100 ???????? 90 ???????????? 110 ???????? 103 ????????? 110 ???????? 105 ?????????? 110 ??????? 104 ???????????? 120 ????????? 120 ?????????? 120 ?? ??????????130 ????????? 130 ?????????? 130 ???????????? 140 ????????? 140 ?????????? 140 ???????????? 150 ????????? 150 ?????????? 150 ???????????? 160 ????????? 160 ?????????? 160 ???????????? 170 ????????? 170 ?????????? 170 ???????? ????180 ????????? 180 ?????????? 180 Observations:When I reacted the marble chips with the
hydrochloric acid, I observed different effects taking place. In the first
instant that the two reactants made contact, I observed nothing occur. However once
the acid had settled inside the flask a second later fizzing began to occur,
producing bubbles that rose to the surface in a whitish mix, after travelling
upward through the acid while some bubbles that formed, stayed on the marble
chips for longer.? As this bubbling
occurred, there was an audible ?fizzing? sound I detected directly from where
the reaction was occurring. I did not observe a colour change different to the
marble chips, nor did I notice a visible gas rising through the already present
air in the flask.Graph ?B? shows the lines of best fit for the four
different concentrations of Hydrochloric acid.Graph
?C? shows the straight trend lines for the four different concentrations of
Hydrochloric acid.Rates
of reactions:To find out whether my predictions are correct, I need to
directly compare the concentration of Hydrochloric acid with the rates of
reaction on a graph. From this I can then make a straight trend line that will
clearly show me what the trend in my results are.To
find the different rates of reaction I divide the increase of gas by the time
in seconds for each Mole of Hydrochloric acid.0.5
= 23 ??????? 180?
=? 0.127 Concentration Rate ????????? 0.5 ???? 0.127 ????????? 1.0 ???? 0.483 ????????? 1.5 0.815384165 ??? ??????2.0 ?????? 0.9 1.0
= 87 ??????? 180?
=? 0.483?? 1.5
= 106 130
=? 0.8153846152.0
= 90 ??????? 100?
=? 0.9 Graph ?D? shows the trend line for concentration of Hydrochloric acid
against the rates of reaction.Analysing:From looking at graph B, I can see my results by looking at the line of
best fit. As time increases so does the volume of gas produced.? For all the moles of acid this increase
starts gradually before then building up to create a steeper part of the curve.
For 1.0M of acid, I can also see this curve begin to fall towards the
horizontal indicating that the gas produced is now decreasing. As for Moles 1.5
and 2.0 of acid, I can see the same pattern where the curve is steepest at
about half way through the test (90s). I expect that if the time were increased
for these two tests, I would see the same drop toward the horizontal. For 0.5M
of acid, the entire pattern is there, but as the results are only deviated a
little it is difficult to see clearly. From looking at graph ?C?, I can clearly see how different the results are
from each other as it shows a straight trend line for each M of acid. The
greatest difference can be seen between 0.5 and 1.0M, the second largest was
between 1.0 and 1.5 and the smallest difference was between 1.5 and 2.0M of
acid. I can also see that there is a pattern at the start of each test.Graph
?E? shows the graph for 1.0M of Hydrochloric acid.In Graph ?E? I have chosen to use a line of best fit as I
can see how some points are not in sync with it. I have also chosen to use 1.0M
of acid to demonstrate a pattern, as it is most prominent in these results. I
noticed that for each set of results, the first point on each line was above
the lines of best fit as indicated.? I realised
that this was occurring when I placed the bung in the conical flask. As I did
this, the air inside the conical flask would of compressed thus pushing air
through the connection tube into the gas syringe. The amount of increase in the
syringe would then be varied as the amount the bung was pushed in.From looking at graph ?D? I can see how concentration
affects the rate of reaction directly by use of a straight trend line. It is
clearly obvious that the rate of reaction is directly proportional to
concentration. Predictions:As I predicted in a statement and a graph, the rate of
reaction is directly proportional to the concentration. This is seen from graph
?D?, where each point for concentration is higher for the rate of reaction than
the previous. Again indicated by the straight trend line that shows positive
correlation. Conclusion:My prediction is correct because the concentration of
reactants is a critical factor that affects the rate of a reaction. This can be
explained by understanding how reactions occur and how different factors affect
them.For reactions to occur, particles must collide with a
sufficient force. The concentration of a reactant determines how many particles
of that particular reactant will be in a solution. If you increase the
concentration, thus increasing the number of reactant particles, then
collisions are more likely to occur. This can be demonstrated clearly by the
diagram below:If you increase the number of collisions between the
particles of reactants, you will consequently increase the rate of reaction.I can also demonstrate this by my rate of reaction
results:1.0M is half of 2.0M of Hydrochloric acid So the rate of reaction for 1.0M should be half the rate
of reaction for 2.0M of Hydrochloric acid1.0M = 0.4832.0M = 0.9As you can see, the rate of reaction is near to doubled,
from 1.0M to 2.0M Evaluation: For this investigation, I found repeated results were
similar to the first, indicating a good method with no substantial mistakes. I
also found my results to be similar to some other people?s, while exceeding the
standard of others. To have fair results in this investigation I needed to
ensure several factors remained constant throughout testing. However I can only
attain a level of accuracy depending on how fair my testing is. I feel, for the
equipment and materials we were allowed to use, I achieved a high standard of
accuracy that gave me excellent results with minimal anomalies.Here I will list the factors that may be the cause for
slight inaccuracies in my experiment. This will show how anomalies can be
accounted for:·
Scales not correctly read or set, giving different
measurements of calcium carbonate.·
Variations in pouring Hydrochloric acid, more or less
agitation of the marble chips, varying surface area.·
Arrangement of chips when placed in flask, varying
surface area for acid.·
Friction in the gas syringe moving at a minimal
pressure, i.e. not smoothly.·
Displacement of gas when inserting bung into flask.·
Calcium carbonate dust that is weighed and then not
used in the reaction.·
Marble chips not of equal surface area.·
Differences in water left from washing the conical
flask after each test.The only way a completely fair test could occur with the
most accurate results, would be to follow the following factors and to account
for the previous ones.§
A completely sterile and constant laboratory
environment. §
Exact Hydrochloric acid volumes or larger quantities of
acid and marble chips i.e. 500ml of acid and 10 grams of calcium carbonate thus
reducing surface area as a factor.? §
Exact chip number, weight and surface area. §
Pure Calcium Carbonate. §
Allow all of the reaction to occur irrespective of
time. §
Take an infinite number of tests and average exactly. §