From the information given above, calculate the: (i). Concentration of A in m/dm (ii). Concentration of B in moldm

here are the solutions to and .

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a) (i) The piece of apparatus used for measuring the portion of $\text{Na}_{2}\text{CO}_{3}$ solution is a pipette.

a) (ii) Three errors in the result presented are:

• The calculated volume for the rough titration ($\text{24.00 cm}^{3} - \text{0.00 cm}^{3} = \text{24.00 cm}^{3}$) does not match the recorded volume ($\text{24.10 cm}^{3}$).
• The second titration reading ($\text{22.5 cm}^{3}$) lacks precision; burette readings should be recorded to two decimal places (e.g., $\text{22.50 cm}^{3}$).
• The average titre value calculation includes values that are not concordant (e.g., $\text{22.75 cm}^{3}$ and $\text{22.40 cm}^{3}$ differ by more than $\text{0.10 cm}^{3}$). Only concordant values should be averaged.

b) (i) The colour of phenolphthalein in the $\text{Na}_{2}\text{CO}_{3}$ solution (which is basic) is pink.

b) (ii) Yes, phenolphthalein is a suitable indicator for the first equivalence point of this titration.

• Reason: $\text{Na}_{2}\text{CO}_{3}$ is a weak base, and $\text{HCl}$ is a strong acid. Phenolphthalein changes colour in the $\text{pH}$ range of $\text{8.2-10.0}$, which corresponds to the $\text{pH}$ at the first equivalence point where $\text{Na}_{2}\text{CO}_{3}$ is converted to $\text{NaHCO}_{3}$.

c) (i) The acid would turn blue litmus paper red.

c) (ii) After the burette had been washed and rinsed with water, the final cleaning step should be to rinse it with the acid ($\text{HCl}$) to be used before filling it.

c) (iii) The type of reaction demonstrated by the experiment is an acid-base neutralization reaction.

c) (iv) The apparatus used to measure the volume of:

• $\text{HCl}$ solution is a burette.
• $\text{Na}_{2}\text{CO}_{3}$ solution is a pipette.

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a) (i) Concentration of A in $\text{mol/dm}^{3}$