The mass of marble chips- The mass of marble chips should also always stay the same to keep it a fair test.
Temperature- This should stay the same because if the temperature is increased the reaction would take less time. Reason being when the temperature is increased, it increases the chance of successful collisions.
Equipment- Have to use the same equipment .
Concentration-
We will test five different concentrations of acid. Three, two point five, two, one point five and one molar acids. We will test each concentration three times.
Below is the table of how to make the acids.
Aim- The aim of this coursework is to investigate the effect of concentration in the rate of a reaction.
Prediction- My prediction for this investigation is if the concentration of the acid is increased, the speed of the reaction in , in which the acid is used, will increase aswell.
Science theory – Without concentrations in our acids, there is a lower number of acid particles, therefore, there is a decreasing chance of a successful collisions happening in our reaction. So when the concentration of the acid is increased, the number of acid particles is increased aswell , therefore, there is a much greater chance of successful collisions happening in our reaction. When the acid is diluted, we get acid molars. These molars count for how much acid and water particle are in the solution. The higher the molar, for example the three molar or the two point five, the more acid particles there are, therefore the increasing chance of a successful collision.
What happens in a reaction?
For a reaction to take place we
need an acid particle to collide
with a calcium carbonate atom.
Hydrochloric acid + Calcium carbonate → Calcium Chloride + Water + Carbon dioxide
The diagram shows 2 particles
colliding, to make a reaction
happen. The reaction will only
take place if there is enough
energy in the reaction.
In this diagram it show you what
happens if there is not enough
energy in the collision. Without
enough energy in the collision
the particle will collide ;however,
they will bounce straight off and
no reaction will take place.
Concentration
As you can see there is no reaction
taking place.
In this diagram, the concentration
of the acid has increased;
therefore, there is a greater chance
of successful collisions taking place.
Dilution
This is a diagram of a concentrated
acid. As you can see there are many
acid particles in the solution.
When diluted, there are less acid
particles in the solution ; therefore
decreasing the chance of successful
collisions.
Temperature
This is a diagram of a substance at
room temperature.
This diagram shows the speed of
the molecules when the
temperature is increased.
Surface area
The surface area is also another another factor which can effect the rate of a reaction. The larger the amount of surface area covered, the faster the reaction taking place. For example………
The reaction in this diagram
is reacting very slow
because there is less surface
area covered.
This is showing more surface
area covered; therefore, the
reaction is a lot faster.
Catalysts
A catalyst is a chemical that can change the rate of a reaction; however, the catalyst does not get effected itself.
This reaction is reacting slowly.
The catalyst is then added,
this makes the reaction
increase in speed; however,
the catalyst is not physically
or chemically changed.
Method
- The first thing we do in any experiment involving acid is to put on a pair of safety goggles.
- We then went and collected the equipment from the equipment trolley. The equipment is listed below……
- Clampstand
- Measuring Cylinder (100 ml)
- Gas Syringe (100cm cubed)
- Hydrochloric acid (three molar) (20 ml)
- A balance (scales)
- Conical flask
- Beaker
- Stopwatch
- Two grams of marble chips
- We set up the clampstand by standing it up right. We then opened up the arm on the clampstand and placed the gas syringe into the open arm of the clampstand and twisted the key on the side of the clampstand arm to close it. We made sure that the units were visible to us so that we could take the readings during the experiment.
- Once the gas syringe was set up , we got the marble chips and went over to the balance. We got a rectangular piece of paper and placed it onto the balance. We then pressed the button with the T sign on it. This then put the units to zero. We got the jar of marble chips and measured out two grams worth of marble chips. We took the two grams of marble chips back to the table we were working on.
- After getting the two grams of marble chips, we got hold of the three molar Hydrochloric acid and also a measuring cylinder. We knelt down until we got to eye level with the twenty millilitre line. We poured in the Hydrochloric acid until it reached the twenty ml line. Then poured it into the conical flask.
- We got hold of the two grams of marble chips ,that we measured out earlier in the experiment , and poured them into the conical flask, quickly put the orange cork into the top of the conical flask, then started the stopwatch.
- We got level with the gas syringe and took a reading of cm cubed every ten seconds for a time span of one hundred seconds. We recorded this in a table.
- We then diluted the three molar acid to make our 2.5, 2, 1.5 and 1 molar acids. We repeated each experiment three times ; reason being, we might of got a step wrong.
- We repeated the experiments for each of the other molars.
- Below is a diagram of the experiment taking place……
Results
Below are the tables for the five different molars that we did.
Concentration of the three molar acid.
Concentration of two point five molar acid.
Concentration of two molar acid.
Concentration of one point five molar acid.
Concentration of one molar acid.
Conclusion:
At the end of the experiment, we found out that the higher concentrated acids, for example three molar or two point five molar, reacted a lot faster compared to the lower molars. And in my prediction, I predicted that the higher concentrated acids would react faster with the marble chips. The gradients of the graphs; however, showed a different story. The average amount of gas (cubed cm) produced for one point five molar acid, was larger than the average amount of gas produced for the two molar acid. The same thing happened for the three and two point five molar acid’s. These are called anomalies.
This diagram is less a
concentrated acid;
therefore, there is a
low chance of successful
collisions.
This diagram is showing a
higher concentrated acid ;
therefore, there is a higher
chance of successful collisions.
Evaluation:
In the experiment, we did certain parts of the experiment very well. We repeated each molar of the experiment three times, just to see if we did any part of it wrong. The results proved that we did each part correctly. The concentrations of the molars we experimented on, we had to make ourselves. To measure the amount of concentrated acid (ml). We knelt down to eye level to measure, because if we stood up and read it , we would be looking at it from a different angle ; therefore, we would have been getting a different reading. The results were abnormal, already said earlier, some of the lower concentrated acids reacted faster. This may have been because of change in room temperature, or most probably the surface area of the marble chips. We could have made two grams of marble chips from a lot of small ones or a couple of big ones. There were a lot of thing we could have done to improve the experiment. For example we could have controlled the room temperature by turning of the heating. We would have would have also restricted the amount of people in the class. The reason would be because it would reduce the overall body temperature. We would also have used a bigger gas syringe. We were only restricted to syringes that could hold one hundred cubic cm’s worth of carbon dioxide. We would also have changed the amount of concentrations we did. We would have done a 0.5 molar test aswell. We also would have probably increased the amount of marble chips to three grams.
