I am going to chose the one result that will show out when it increase very quickly at the start and have increase slowly at the end and eventually stop reacting, and I need a result that can show it all, or most of it, so I carry out the experiment like this:
P.S. Do this experiment for the 4 different masses of the marble chips
- I measure the weight of the marble chips that I need on a mass balance.
- I measure the volume of 20cm³ of hydrochloric acid for my experiment which I will do the same each time
- I set the apparatus like this:
- Put the dilute hydrochloric acid into the flask while press the stopwatch.
- Put the top on and give it a standard shake – shake it twice in clockwise direction, to make the reaction going on.
- Measure the reading in the gas syringe every 10 seconds and do it 10 times.
- Put the results into the table.
And I got the result like this:
The result of the experiment
I will chose the 2.00g one because it has a very different range of speed which change very quickly. Although it have gone through 100 cm³, the limit of the syringe, I will take out another experiment, which make the 2.00g marble chips constant and start the change the volume of the hydrochloric acid.
I am going to do the same experiment but I measure the marble chips in 2.00g all the time and I am going to measure the hydrochloric acid in 5 different variables – 5 cm³, 10 cm³, 15cm³ and 20 cm³ and I go the result like this:
The result of the experiment
I will chose the 10 cm³ because it haven’t went out of the limit of the syringe even I use the highest concentration and the result change increase very quickly so I will chose 2.00g of marble chips, 10 cm³ of HCL concentration of 0.25 mol/dm³, 0.5 mol/dm³, 1 mol/dm³, and 2 mol/dm³ and I will repeat my experiment 3 times for each concentration so I can do my average for my main experiment so I can find out is the quantitative relationship that I predict is right. But because I want to find out the relationship between these different concentrations more clearly, I will put another concentration between 1 mole/dm³ and 2 mole/dm³, which I made myself – 1.5 mole/dm³. And I hope that there will be carbon dioxide:
0.25*0.01=0.0025mole 0.0025*24=0.06dm³=60cm³ will produce
0.5*0.01=0.005mole 0.005*24=0.12dm³=120dm³ will produce
1*0.01=0.01mole 0.01*24=0.24dm³=240cm³ will produce
1.5*0.01=0.015mole 0.015*24=0.36dm³=360cm³ will produce
2*0.01=0.02mole 0.02*24=0.48dm³=480cm³ will produce
So when the concentration doubles, the gas produce will be doubles.
Obtaining
Main Method
Safety precautions – HYDROCHLORIC ACID is CORRSIVE
– Wear SAFETY GOOGLES
I am going to do the followings:
- I measure the weight of the marble chips of 2.00g that I need on a mass balance.
- I measure the volume of 10cm³ of hydrochloric acid of 0.25 mol/dm³, 0.5 mol/dm³, 1 mol/dm³, 1.5 mol/dm³ and 2 mol/dm³ for my experiment in the measuring cylinder which I will do the same each time.
- I put the marble chips into the flask.
- I set the apparatus like this:
- Put the dilute hydrochloric acid into the flask while press the stopwatch.
- Put the lid on and give it a standard shake – shake it twice in clockwise direction, to make the reaction going on.
- Measure the reading in the gas syringe every 10 seconds and do it 10 times.
- Repeat the same concentration for 3 times.
- Get the average of three results of that time to a next column.
- Put the results into the table.
To make it accurate, I will do a standard shake because this will make the reaction going on at the start. And the lid of the flask may leak some gas out, so I need to press it harder to avoid it.
The result of the Main Experiment
*This shown as an anomalous result so will not include it.
Analysis
Fig.1
Fig.2
In this two graphs on fig.1, which is the three experiments I have did for my concentration 0.25mole/dm³. And the fig.2 is the gradient of both three averages. The gradient is found by taking two points on the line and, moving left to right from one point to the other, evaluating the fraction: distance moved up/ distance moved across. On this graph it show the gradient of this graph is 4.8/10 cm³/s, which is 0.48 cm³/s, which is very low.
Fig.1
Fig.2
In this two graphs on fig.1, which is the three experiments I have did for my concentration 0.5mole/dm³. And the fig.2 is the gradient of both three averages. On this graph it show the gradient of this graph is 11/10 cm³/s, which is 1.1 cm³/s, which is very higher than the concentration 0.25mole/dm³, which have the gradient of 0.48 cm³/s.
Fig.1
Fig.2
In this two graphs on fig.1, which is the two experiments I have did for my concentration 1 mole/dm³. I just have 2 results because the second result is higher than the others, which have:
I think this result happen like this because maybe the marble chips in the crucible flask some of them are very powdery and the hydrochloric acid will reacted them very quickly first because they have altogether have a very large surface area, then after reacting the powdery part there is very big marble chips and it react with the hydrochloric acid very slowly because they have less surface area all together. So the carbon dioxide gas produce very slowly at the end in which it don’t reach the other’s result which will meant to get, so that is why we have a result which is less then the others.
And the fig.2 is the gradient of both averages. On this graph it show the gradient of this graph is 25/10 cm³/s, which is 2.5 cm³/s, which is very higher than the concentration 0.5mole/dm³, which have the gradient of 1.1 cm³/s.
Fig.1
Fig.2
In this two graphs on fig.1, which is the three experiments I have did for my concentration 1.5mole/dm³. And the fig.2 is the gradient of both three averages. On this graph it show the gradient of this graph is 41.3/10 cm³/s, which is 4.13 cm³/s, which is very higher than the concentration 1mole/dm³, which have the gradient of 2.5 cm³/s.
Fig.1
Fig.2
In this two graphs on fig.1, which is the three experiments I have did for my concentration 2 mole/dm³. And the fig.2 is the gradient of both three averages. On this graph it show the gradient of this graph is 60/10 cm³/s, which is 6 cm³/s, which is very higher than the concentration 1.5 mole/dm³, which have the gradient of 4.13 cm³/s.
Fig.1
This graph shows all the averages of all the concentration that I have done. On my previous calculation, the 0.25 mole/dm³ have the gradient of 0.48 cm³/s, 0.5 mole/dm³ have the gradient of 1.1 cm³/s, 1 mole/dm³have the gradient of 2.5 cm³/s, 1.5 mole/dm³ have the gradient of 4.13 cm³/s, and the 2 mole/dm³ have the gradient of 6 cm³/s. On each case, you can find out that every concentration I have done which doubles, the gradient will doubles. There are all the examples:
Use the first result of 0.25 mole/dm³:
0.5 mole/dm³/0.25 mole/dm³ 0.5/0.25=2
So from the 0.25 mole/dm³ I will predict to get in my 0.5 mole/dm³: 0.48*2=0.96
Comparing with the gradient from my result of 0.5-mole/dm³: 1.1/0.96*100%=114.58%
This means that my result in 0.5 mole/dm³ was: 114.58% more than the predicted result.
And so on, on the other result:
1 mole/dm³/0.5 mole/dm³ 1/0.5=2 1.1*2=2.2 2.5/2.2=113.64%
1.5 mole/dm³/1 mole/dm³ 1.5/1=1.5 2.5*1.5=3.75 4.13/3.75=110.13%
2 mole/dm³/1.5 mole/dm³ 2/1.5=1.3 4.13*1.3=5.369 6/5.396=111.19%
You can see that the quantitative relationship of the concentration and the gradient is proportional to each other, nearly is 1 to 1 relationship. Although the relationship in my experiment is shown as between 114.85% to 110.13% but because the errors in the experiment such as the size of the marble chip are very random, the relationship would be closer to 1 to 1 relationship. This means that the volume of CO2 produce will have increase (rate of reaction increase) when the concentration of the hydrochloric acid increase because higher the concentration there are more particles in the solution, so there are more collisions.
This means that my prediction does match up my data. But the gradient that I have got in my result usually is less than the one that I predict, because the marble chips that are inside the flask were randomly sized (I will say more in my evolution). But I think it is good enough of these results because some of the errors of the experiment are not very far from the result that was predicted.
Evaluation
There is one anomalous result when I do the experiment using the concentration of 1 mol of the second repeat that the result start off very rapidly the rate of producing the carbon dioxide is getting slowly up at a very lower result than the others and it was said as an anomalous result because it was 6 cm off the others.
I think this result happen like this because maybe the marble chips in the crucible flask some of them are very powdery and the hydrochloric acid will reacted them very quickly first because they have altogether have a very large surface area, then after reacting the powdery part there is very big marble chips and it react with the hydrochloric acid very slowly because they have less surface area all together. So the carbon dioxide gas produce very slowly at the end in which it don’t reach the other’s result which will meant to get, so that is why we have a result which is less then the others.
I think the result that I got is not very accurate because:
- During the experiment I find out that the regular marble chips are very powdery underneath and there are same very large ones at the top, which make the reaction very unstable. When we measure the marble chips using the weight the digital measurement will show the grams of the marble ship in 2 decimal places, which I think this is not accurate enough because I have try if I put a little marble chips powder on top, the measurement sometime cannot feel there is weight, but which means these powder will give the experiment an extra boost at the start of the experiment even though the weight said there is 2.00g of marble chips there.
- I find out that the crucible flask is not very good because when you but every apparatus joint together, when you put the top of the flask into it, the gas syringe will go up a little because there is a volume of gas moving in during I put the top in.
- Using a gas syringe is not really accurate because gas can be compressed, so when some gas come in, the syringe inside will have its mass to push the gas inwards which make the gas compress and have less volume, and because it has no decimal place, when a slow reaction occur, the result may be between the two readings, which I would always count as 0.5cm which is not that accurate because it may be the reading of 0.5 more or lower.
- And at the start of each experiment we will use a standard shake to make the reaction going on, but this is not very accurate because even I have every shake on the same direction, the energy I put into the shake will be different, which you cannot really control each shake will be the same all the time.
I can improve my result by do the following:
- We can use some calcium carbonate cubes, which have their surface area that we knew, so every time the experiment will be accurate if we use a certain number of cubes because there are no powder nor any bigger chips. This can solve the problem of the size and the problem on the decimal place of the weight.
- We can use something instead of the lid, using a container cover up the top, and you want to pour the acids in, you twist a screw and the acid will fall into the flask and the reaction will occur, which this solve a problem of the lid.
- We can use a digital syringe, which can accurately in decimal places calculate the volume of gas produce, and it is like a bag to collect the gas which nothing like the syringe. So this can solve the problem of the accurate and the compress of gas of the syringe.
- I think using a machinery to shake up the reaction will be more accurate than a standard shake, which is better than a standard shake, and the machine will give out the same shake each time, which will make the experiment fair.
I think I still can drew the same conclusion for this experiment because it is still reliable enough, this is because my result still can show a normal curve out the graph, which I have predict it before and the quantitative relationship does match up my data, so my conclusion still can be drew out.
I can make other investigate on the other variables by investigate the mass of the marble chips can be vary the reaction rate, I can do the same method like this and probably find out the mass of marble chip increase by 2, the reaction will increase by 2, which is similar to the experiment to this. I may extend my experiment for using other acids such as sulphuric acid (H2SO4) or using nitric acid (HNO3). I may investigate will the rate of the reaction varies if the acids have more protons - H2SO4 which has 2 H+ ions and HNO3 which has1 H+ ion. Or I can investigate the difference between the strong of weak acids: ethanoic acid (CH3COOH), which is a weak acid and sulphuric acid, is a strong acid. I may change the material instead of carbonates: metals (e.g. zinc) or other kinds of carbonates. I can collect the results using another method such as measuring the change of mass during the experiment, by putting the flask on a mass balance.
