Investigation into how the amount of sodium carbonate used in a reaction between itself and hydrochloric acid affects the amount of carbon dioxide that is produced during the reaction.

Preliminary investigation

I know that 1 mole of any gas is equal to 24dm3 or 24000cm3

I can use this equation if I want to work out the number of moles of gas produced in the reaction.

Apparatus

Sodium Carbonate

Hydrochloric Acid (2M)

Distillery tube

Ignition tubes

Plastic Basin filled with water

Volumetric Flask

Filter funnel

Balance (0 – 200g)

Measuring cylinders (250cm3 and 50cm3)

Method

SAFETY: As a safety precaution, wear goggles throughout the experiment

1. Weigh the mass of the ignition tube and record it.
2. Weigh out 0.3 grams of sodium carbonate and put it into the ignition tube
3. Get the 50cm3 measuring cylinder, and carefully measure 40cm3 of hydrochloric acid. Pour this acid into the volumetric flask using the filter funnel.
4. Fill up the big bowl and 250cm3 measuring cylinder and carefully put the measuring cylinder upside down into the bowl of water. If you do this very carefully, then no gas will get into the tube. If any gas does get into the measuring cylinder, deduct the amount away from the final amount of gas that is produced.
5. Make sure that the end of the distillery tube is ready to deliver the gas into the measuring cylinder, and make sure that the bung is on the flask. Then carefully drop the ignition tube with the carbonate in it into the volumetric flask, trying to make sure that the carbonate doesn’t stick to the sides.
6. Shake the flask to encourage the reaction, and only remove the distillery tube once all of the sodium carbonate has reacted and there are no more gas bubbles being produced.
7. Once the reaction is over, calculate the amount of carbon dioxide gas produced by reading where the water level has reached in the test tube. Then take away this value from the one that you got before the reaction (presuming you did get a value) to get the volume of gas produced. Record the result.
8. Repeat the same method again for 0.45g, 0.6g, 0.75g, 0.9g and 1.05g. Do the experiment twice for each mass of carbonate to check if your results are reliable. If they aren’t reliable (if your second result is not within approximately 10 – 15% of the amount of gas produced the first time), do the experiment a third time. If, when the experiment is done for a third time, the reading is not within 15% of your first reading, but second reading, then don’t repeat it a fourth time, as the first attempt will be considered as anomalous.
9. Make sure that you have recorded all of the results in an appropriate table.

Preliminary results

In my preliminary experiment, I only did the experiment for two different masses of the sodium carbonate – approximately 0.3g and 0.8g. This is because by doing two that are quite far apart I would see the general pattern of the experiment. There is no need to repeat the preliminary experiments, as they results are used only as a rough guide for the real experiment.

Mass of ignition tube = 0.98g

Mass of ignition tube and sodium carbonate = 1.77g

Mass of sodium carbonate = 1.77 – 0.98 = 0.79g

Volume of carbon dioxide gas given off = 132cm3

Moles of CO2 = 132 / 24000 = 0.0055 moles

Mass of ignition tube = 1.1g

Mass of ignition tube and sodium carbonate = 1.4g

Mass of sodium carbonate = 1.4 – 1.1 = 0.3g 

Volume of carbon dioxide gas given off = 52cm3

Moles of CO2 = 52 / 24000 = 0.0021 moles

These preliminary results show part of what I had predicted. It shows that as the amount of carbonate used increases, so does the volume of the carbon dioxide gas, which was a part of my prediction. However, it is yet to be proved whether the two are directly proportional, which I will find out in the real experiment.

Factors affecting the reaction

There are many different factors which will affect the reaction. They are:

Input variable 

Amount of sodium carbonate used in the reaction. As the amount of carbonate used rises, so does the amount of CO2 produced

Outcome variable  

Volume of carbon dioxide gas produced by the reaction. Increases as the amount of carbonate used increases

Constants  

Type of carbonate – If I use a different carbonate, the amount of gas produced may increase or decrease depending on which carbonate I use. Also, I am only investigating the effects of sodium carbonate and not any other types of carbonate

Volume of acid – If I use less acid, e.g. 30cm3 , then all of the carbonate may not react due to there not being enough acid. Therefore I am making sure that I use the right amount. Not too little so that the reaction isn’t fully completed, or not too much as to waste a lot of acid.

Concentration and type of acid – I think that if I used a stronger acid such as nitric acid or increased the concentration of the acid then I think more gas would be produced. Also, I am investigating the amount of carbon dioxide gas given off when the carbonate is reacted with HCl and not any other acid

Results

I did the experiment twice for each different mass value of the carbonate. In the table below I have put a column showing the difference in percent of the second reading from the first reading. If they are not within 10% of each other, a third reading was taken.

 

I have plotted the results that are in the above table on graph1

Also, from knowing the amount of gas given off, I can work out the amount of moles of carbon dioxide given off. In the table below, for the value of moles, I took an average of the two readings and then worked out the number of moles.

I have plotted the results from the table above on graph 2

By looking at the graph, I can draw many conclusions

Conclusions

1. As the mass of sodium carbonate increased, so did the amount of carbon dioxide gas produced.
2. There was a linear relationship between these two variables.
3. It also shows that the amount of carbonate used is directly proportional to the amount of carbon dioxide gas produced.
4. The results that I had obtained supported the prediction that I had made.
5. The method that I used produced reliable results, as they were within the zone that I would have expected them to be in if they were reliable.