The document summarizes a chemistry experiment that investigated how the concentration of hydrochloric acid (HCl) affects the rate of reaction when magnesium (Mg) is added. It was hypothesized that higher HCl concentrations would increase the reaction rate. Experiments were conducted using different HCl concentrations from 0.1M to 0.5M. The results showed that higher concentrations produced hydrogen gas faster, supporting the hypothesis. A graph of the reaction rates demonstrated they increased quadratically with increasing HCl concentration. However, the conclusion noted some weaknesses in temperature control and material reuse that could be improved.
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
Science example
1. Makiko Hidaka
Mr. Eales
Period 1: Chemistry
Rate of reaction
Introduction:
“The rate of reaction” means, “how fast the substances make reactions”.
The rate of reaction is affected by many factors, such as heating. By heating a
substance, molecules are moved and are collided into each other faster than non
heated condition. In this way, heating of substances can make the ration of reaction
faster. Another example of factor that affects the rate of reaction is the surface areas
of substance. The bigger surface can increase the rate of reactions (faster reaction).
Same as heating, the molecules have more chance to collide into other molecules.
The concentration (the amount of a substance in a liquid or in another
substances (1concentration = 1 M)), also affect the rate of reaction. However, it is not
known whether more/less concentration would make reaction faster/slower. It is
examined in this lab. Same amount of magnesium (Mg) is added into different
concentration of hydrochloric acid, (HCl). Those HCI will bubble and produce the
hydrogen gases. (H2) (The chemical equation for this experiment is Mg + 2HCl →H2
(g) + MgCl2.)
The research question for this lab is “how does the concentration of HCl
affects the rate of producing the hydrogen gases when Mg is added into the HCl ((aq)
=aqueous).”
Hypothesis:
The high concentration of HCl will increase the rate of reaction (faster
reaction). In “High concentrations”, or “more molecules in the HCl”, magnesium has
more chance to collide into each other. This hypothesis can be supported by a fact that
the stains disappear fast in the high concentration of bleach. (Information by “New
coordinate Science, 3rd Edition Chemistry. Page 132.”) Therefore, increasing the
concentration of HCl makes the rate for reaction faster.
Materials:
1. Test tubes 2. Syringes 3. Tops witch attached with a little tubes 4. Water
5. Magnesium (Mg) (see figure 1) 6. Thermometer 7. Beakers 8. Stop watch
9. Graduated Cylinder 10. 0.1 M (=concentration) HCl 11. 0.2 M HCl 12. 0.3 M HCl
13. 0.4 M HCl 14. 0.5 M HCl 15. Ruler 16. (Dropper)
Procedure:
A temperature of HCl was measured with a thermometer. The temperature of
HCl was 25℃. The temperature of HCI should be controlled, because the temperature
affects the rate of reaction. (A reason is explained in the introduction.) Water full of a
syringe was put into a cylinder to measure the volume of the syringe. The volume of
syringe was 4.9ml. This procedure was necessary to know because an equation of rate
is showed as ml/time (second) (Not rate = 1 syringe / time (s)!) 8ml HCl was
measured by using a graduated cylinder (or a dropper). 6cm Mg was measured by the
ruler and cut. The amount of HCl and Mg should be controlled. Also, Mg should be
shortened, because whole Mg would not be filled in the HCl. A syringe was filled up
with the water. Both 8ml 0.1 M HCl and 6cm Mg was put into a test tube. The
2. hydrogen gases were formed. A top which attached by a little tube was put on a test
tube. As fast as possible, (because the rate of the reaction will decrease, as the time
passed by,) an opening of syringe which contains water in it was attached with that
test tube. Time of the reaction is counted by stop watch from this point. The air of test
tube move into the syringe. The water of the syringe starts to flood. (See figure 2.) A
time counting is stopped once a syringe is filled up with the air. The rate of reaction is
measured by using an equation. The rate = 4.9ml / amount of times was taken to fill
up a syringe with the air. The experiment was continued with different concentrations
of HCls. It should be carried with the controlled amount of Mg, HCl, controlled
volumes of syringe and controlled HCl’s temperatures. The experiments were done
with all 0.1~ 0.5 concentrations of HCls.
Figure 1: The magnesium used in
this lab looks like a ribbon, so it can
Figure 2: This is a picture of HCl, a
cut into 6cm.
syringe filled with water, and a little
(Picture from:
amazingrust.com/.../Magnesium_Ribbo
test tube with a top.
n_small.jpg) This picture also shows that the
Hydrogen gases were produced and
the airs were got into a syringe.
(Picture from class images)
3. Data:
Controlling: Temperature of HCl= 25 ℃
Amount of HCl = 8ml
Magnesium = 6cm
Time of reaction with different concentrations
Concentration of HCl Amounts of times to react (s)
(M) Trial 1 Trial 2 Trial 3 Average Uncertainty(±)
0.1 - - - - -
0.2 94 62 77 78 16
0.3 59 40 53 51 10
0.4 28 29 28 28 1
0.5 22 20 25 22 2
Table1: This table shows the times those different concentrations of HCl take to fill
up a syringe. The experiments were done 3 times with each concentration, except for
0.1 M HCl. 0.1 M HCl experiment was not completed. There was no enough 0.1 M
HCl and no enough time left for experiment. All averages and uncertainties were
rounded nearest tenth.
Average time of reaction with different concentrations
Figure 3: This is the graph clearly shows that as the concentrations of HCl increase,
the time of reaction decrease. It can be expected that 0.1 M HCl would had the
slowest time of reaction.
4. Rate of reaction with different concentrations
Concentration of HCl Ave. rate of reaction (ml/ s)
(M)
0.1 -
0.2 0.063
0.3 0.096
0.4 0.175
0.5 0.223
Table 2: The average times of reactions were calculated and changed into rates of
reactions. Average rates of reaction were rounded nearest thousandth.
Sample Calculation:
Rate of producing Hydrogen gases = volume of syringe (ml) / time to produce the
hydrogen gases (s).
With 0.1 M HCl, 4.9ml syringe filled up with hydrogen gases in 94 second.
→4.9/ 94 = 0.05 (ml/s)
→With 0.1M HCl, 0.05 ml, hydrogen gases was produced in every 1 second.
Average rate of concentration with different concentrations
Figure4: this graph clearly shows that as the concentrations of HCl increase, the rate
of reactions will also increase. As the concentrations of HCl increase, the amount of
producing the hydrogen gases in a second will also increase.
5. Conclusion:
A graph shown in figure 4 clearly defines a research question, “how does the
concentration of HCls affect the rate of producing the hydrogen gases when Mg was
added.” According to a graph, it shows that as the concentration of HCl increase, rate
of reaction also will increase. In addition, it was defined that rate of reactions and the
concentrations of HCl has a relationship called, quadratic relationship. This
relationship shows that when a concentration of HCl will be doubled, a rate of that
concentration is going to be a double square rate. For example, when a rate of 0.1 M
HCl was 0.063, a rate of 0.02 M HCl is going to be 0.008 (= 0.063 ^2 *2. (Rounded
thousandth)).
However, this quadratic relation only applies to when 6cm Mg was in ribbon form,
the temperature of HCl was 25 ℃, amount of HCl were same, and it only works for
0.1 ~ 0.5 M HCl’s rate. It might work in situations other than these, but it had not
been experimented.
Evaluation: There are some weak points to prove that this conclusion was correct.
Firstly, a temperature of HCl was not completely in control. When the magnesium
was added into the HCl, the temperature was increased. To improve this problem, the
temperature can be cooled drown by soaking a test tube into the water during the
reaction was occurred.
A next weakness was that the Mg was reused over and over during the experiments. It
might be oxidized and affected the rate of producing the hydrogen gases. Therefore,
the new magnesium should be used for each experiment.
A last weak point was that the concentration of HCl was decreased during the
hydrogen gases were formed. The HCl was used by producing the hydrogen gases.
The HCl did not have enough molecules to react with Mg.
To improve this weakness, the experiment should start with huge amounts of HCl, so
that can have more molecules to make a reaction with Mg.