A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown. At the start of the experiment a coloured chemical is added to the NaOH. (i) Name the coloured chemical added to the NaOH. (ii) What is the purpose of adding this chemical? (iii) Name the piece of equipment labelled X. (iv) The student noted the volume of HCl added to NaOH and then repeated the procedure twice more. The results are shown in the table below. Titration Volume of HCl (cm³) 1 19.7 2 19.2 3 19.3 Calculate the average volume of HCl added. (v) Describe the next steps the student would take to prepare a pure sample of sodium chloride (NaCl).

Junior Cycle Science Solutions: A student carried out a titratio

A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown - Junior Cycle Science - Question c - 2017

Question c

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A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown. At the start of the experiment a coloured che... show full transcript

Worked Solution & Example Answer:A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown - Junior Cycle Science - Question c - 2017

Step 1

Name the coloured chemical added to the NaOH.

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Answer

The coloured chemical added to the NaOH is a pH indicator, such as phenolphthalein or bromothymol blue.

Step 2

What is the purpose of adding this chemical?

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Answer

The purpose of adding a pH indicator is to visually show when neutralisation occurs, indicating that enough acid has been added to the base.

Step 3

Name the piece of equipment labelled X.

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Answer

The piece of equipment labelled X is a burette.

Step 4

Calculate the average volume of HCl added.

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Answer

To calculate the average volume of HCl added, we add the three volumes together and then divide by the number of titrations:

$ext{Average volume} = rac{19.7 + 19.2 + 19.3}{3} = rac{58.2}{3} = 19.4 ext{ cm}^3$

Step 5

Describe the next steps the student would take to prepare a pure sample of sodium chloride (NaCl).

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Answer

The next steps the student would take are:

Repeat the titration without the pH indicator to avoid contamination.
Pour the resulting solution into an evaporating dish.
Heat the solution gently to evaporate off the water, leaving behind the pure sodium chloride crystals.

A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown - Junior Cycle Science - Question c - 2017

Worked Solution & Example Answer:A student carried out a titration of hydrochloric acid (HCl) against sodium hydroxide (NaOH) using the apparatus shown - Junior Cycle Science - Question c - 2017

Name the coloured chemical added to the NaOH.

What is the purpose of adding this chemical?

Name the piece of equipment labelled X.

Calculate the average volume of HCl added.

Describe the next steps the student would take to prepare a pure sample of sodium chloride (NaCl).

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