titrations and calculations sc14d

Question 1

Describe the steps in carrying out an acid-alkali titration.

Answer 1

• Using a pipette, measure out a set volume of the alkali into a flask.
• Add a few drops of an indicator - usually phenolphthalein or methyl orange.
• Fill a burette with a standard solution (a known concentration) of acid
• Use a burette to add the acid to the alkali a bit at a time. Swirl the flask regularly. Go slowly (a drop at a time) when you think the alkali is almost neutralized.
• The indicator changes color when all the alkali has been neutralized - phenolphthalein is pink in alkalis but colorless in acids, and methyl orange is yellow in alkalis but red in acids.
• Record the volume of acid used to neutralize the alkali (called the titre).
• Repeat this process a few times, making sure you get very similar results each time. You can then take the mean of your results

Question 2

Calculate the number of moles of solute in a given volume of solution.

Answer 2

amount (mol) = concentration × volume

Question 3

Deduce the mole ratio of acid to alkali from
a balanced equation.

Answer 3

The ratio of the amounts of two substances as shown in a balanced equation.

Question 4

Calculate the concentration of a solution
using the results of an acid-alkali titration.

Answer 4

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Question 5

Calculate the volume of solution required in an acid-alkali titration, given the
concentrations of both the acid and the alkali.

Answer 5

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