Design two experiments, one using titration and one using gas collection to show that H2SO4 is a dibasic acid.

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Chemistry Practical Write-Up

Aim: Design two experiments, one using titration and one using gas collection to show that H2SO4 is a dibasic acid.

Gas Collection Experiment

Prediction: If H2SO4 is dibasic it should give off a volume of hydrogen molecules, equal to the volume of H2SO4 used, below I have calculated how much gas to expect:

Apparatus: Conical Flask, Magnesium, H2SO4, Bung, delivery tube, bowl of water, measuring cylinder.

Diagram:

Method:

  • Setup Apparatus as shown in the diagram.
  • Fill a conical flash with 25cm3 H2SO4.
  • Fill the measuring cylinder with water, making sure there are no bubbles, and turn it upside down in the water bath.
  • Drop the magnesium into the conical flask, and place the quickly place the bung on top.
  • The hydrogen gas will begin to displace the water in the measuring cylinder, wait until this stops, and record the results in a table like shown below, repeat until you have 3 results and calculate the average amount of gas evolved.

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To keep the results accurate we will keep all equipment and solutions used the same every time, we will do this experiment 3 times and take the average of the readings, and use this to see if H2SO4 is dibasic, theoretically we should measure 0.6dm3, although we may not get this exact reading for many reasons:

  • Inaccuracy when measuring solutions/weight of Mg.
  • Impurities in the solutions used e.g: Concentrated H2SO4:“Purity: 95%-98% Pure” [1]
  • If all the reactants weren’t used up in the reaction.
  • Inaccuracy taking the gas reading

Titration Experiment

Prediction: Based on my ...

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The spelling, grammar and punctation are all fine. The use of technical terms is also flawless and the student clearly understands the meaning of them. The student follows the classic example (expect in the positioning of the 'preliminary work' section) of a science student writing up an experiment. Whilst it is 'classic', it is highly recommended that students stick to this structure as it is a very good basis to build upon, making writing the work easier. It also provides a very clear layout for the work which is beneficial to the student as the examiner can find information easily and follow through to the conclusion logically. The list of references at the end is perhaps more suited to being listed as a footnote. Yet, this does not affect the mark the student will get.

The student shows a high level of understanding of the topic and question set. They address it well throughout the piece of work in a logical order. They made the appropriate conclusion., however, I am wondering why the data was not typed into this piece of work. The gaps made in the table were obviously for recording results which were then not recorded electronically (I presume they printed the document off and recorded it by hand). This should not affect the mark however. The examples used in the piece of work is sound and the attention to detail is highly commendable. This assures the student gains high marks as it demonstrates that they have a clear understanding that is supported by detailed knowledge as evidence.

The student has addressed the question well and has laid out the work well. The titles guide the examiner well and present her aim and conclusion in a logical order. The only flaw I can see is the section 'preliminary work'. I was not exactly sure why the section was last and why it was so short. I had expected such sections to be longer and more detailed in suggesting why the work is necessary before conducting an experiment. Also, the diagrams (presumably of the apparatus) did not show up - most likely due to incompatibility of the softwares used. The use of diagrams is very good here and would help illustrate the points made.