To find out the molarity of the acid using 25cm3 of acid to neutralise 0.10 mole of alkali

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Chemistry Coursework

To find out the molarity of the acid using 25cm3 of acid to neutralise 0.10 mole of alkali

Analysis

We used a pipette to measure the acid and this was a measurement of 25cm3. A burette was used to measure the alkali, along with methyl orange as an indicator because this has a pH range of 3-7.

We did the experiment 5 times to get a range of results.

When doing an experiment the apparatus can have a error or you could actual read it wrong. Referring to “Nuffield Advanced Chemistry” as my secondary source, pipettes and burettes have a percentage error. Pipettes have and accuracy of one drop. The volume of one drop is 0.05cm3. Burettes have graduations every 0.1cm3 and this also can be 0.05cm3 too high or too low.

The percentage error for the Pipette =

0.05cm3

               X 100 = 0.2%

25cm3   

The percentage error for the Burette = Smallest reading = 28.60

0.05cm3

                 X 100 = 0.175%

28.60cm3

The results that will be excluded are 1 and 3, which are 29.20 and 28.60.

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Therefore for the average we should only use results 2, 4 and 5, which are 28.80, 28.85 and 28.75cm3.

So the average of these is 28.80cm3.

We now use 28.80cm3 to work out the molarity of the acid.

The equation for the titration can be sown as:

H2SO4 + Na2CO3                             H2O + Na2SO4 + CO2

This has a ratio of:

H2SO4 + Na2CO3                             H2O + Na2SO4 + CO2

   1    :    1

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