'Investigating how changing concentration affects the rate of reaction between Marble chips and hydrochloric acid.

Lauren Ardolino

10AH

Planning

The title of this investigation is ‘Investigating how changing concentration affects the rate of reaction between Marble chips and hydrochloric acid. My aim is to figure out how much concentration affects the rate of marble chips in hydrochloric acid. There are lots of different factors that affect this reaction such as using the same amount of marble chips every time and using the same size eg. Small, medium or large. You need to make sure that the lid (stopper, bung) is completely on, as gas can escape if the lid is not fitted properly. The syringe should always be at 0 to start, so you don’t get the wrong results. The temperature can affect how fast the marble chips work and may also give you the wrong results. I predict that the higher the volume of hydrogen (cm3) the quicker the reaction will take place. Scientific knowledge that I think this will happen is that the higher the volume of hydrogen will make the marble chips react quicker than a lower volume of hydrogen. The chemical equation for this investigation is:

Marble + Hydrochloric Calcium + Carbon + Water

Chips Acid Chloride Dioxide

We timed the experiment up to 65 seconds and we used volumes: 1, 1.5, 2.0, and 2.5 of hydrochloric acid. A main variable we changed was the syringe, this was a problem because one syringe was smaller than the other and this would mean the results are wrong for one of the parts of this experiment.

Apparatus

Clamp

Syringe

Side armed conical glass

Hydrochloric acid

Marble chips

Stopwatch

Safety Precautions we took

For this experiment we had ...

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Marble + Hydrochloric Calcium + Carbon + Water

Chips Acid Chloride Dioxide

Apparatus

Clamp

Syringe

Side armed conical glass

Hydrochloric acid

Marble chips

Stopwatch

Safety Precautions we took

For this experiment we had to make sure we used full safety such as:

Wearing goggles at all times

Tying hair back – could get in the way of experiment and might not be able to see experiment properly.

Putting all bags and coats under tables – you could slip over while carrying marble chips, glass ware or acids

Washing hands if there was a spillage of acid

Always check the syringe is not coming out to far – if there was a lot of CO2 being produced the syringe would move quicker and could shoot out to fast

Hold syringe properly - hold tube and outer tube

Wipe up ALL spillages

Method

Firstly, we weighed out 5g of small marble chips; we then added them to 20cm3 hydrochloric acid in a side armed conical. This conical was connected to the gas syringe and as soon as the marble chips were added to the hydrochloric acid, we started the stopwatch and from the on we took the reading of the volume in the gas syringe when a certain point is reached.

Analysis

As you can see on the graph 2.5 produced the most amount of CO2m, however on the graph you can see a major fault and that is that 1.5 has overtaken 2.0 on how much gas was produced. It is only a slight fault at the maximum gas produced as 1.5 produced 77.5cm3 and 2.0 produced 75cm3.

This is what I expected and this was my prediction, although there was a fault you can still see clearly that the experiment went quite well because everything seems in the right proportion. So therefore, it is correct to say that the higher the concentration of acid, there is a increasing gas produced. I think an anomalous result is in concentration 1 at 65 seconds - there is a great leap from 47.5 to 64.5 and you can see on the graph that this result is out of place. This could have been caused by the bung was not in properly.

Evaluation

My personal opinion of how this experiment went is that is gone very well. I think that a few minor mistakes were made, but the experiment still went well, and our results have come up quite well. I think on some occasions we may have misread the reading and this could have given an anomalous result. Errors could have also occurred if weighing the wrong amount of marble chips or measuring the wrong amount of hydrochloric acid - this could have had a major affect on the results. If I were to do this experiment again, I would use the same syringe so the results could have been higher than 50. To conclude my investigation I think the experiment went well and we were accurate with our method.