2. A 0.10 M standard solution of hydrochloric acid (HCl) was used to find the concentration of a sodium hydroxide (NaOH) solution by titration - Leaving Cert Chemistry - Question 2 - 2007
Question 2
2. A 0.10 M standard solution of hydrochloric acid (HCl) was used to find the concentration of a sodium hydroxide (NaOH) solution by titration. The piece of equipmen... show full transcript
Worked Solution & Example Answer:2. A 0.10 M standard solution of hydrochloric acid (HCl) was used to find the concentration of a sodium hydroxide (NaOH) solution by titration - Leaving Cert Chemistry - Question 2 - 2007
Step 1
Name the piece of equipment A.
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Answer
The piece of equipment A is a pipette.
Step 2
Which of the two solutions is usually measured using the piece of equipment labelled A?
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Answer
The solution measured using the piece of equipment A is the sodium hydroxide (NaOH) solution.
Step 3
Name the piece of equipment used to measure the second solution used in the titration.
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The piece of equipment used to measure the second solution is a burette.
Step 4
Describe the correct procedure for rinsing and filling A.
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To properly rinse and fill the pipette (A), first rinse it with deionised water. Next, rinse it with the solution it will measure, filling it part way and then expelling it, ensuring that the solution coats the inside of the pipette. Finally, fill the pipette above the line, keeping the liquid's meniscus resting on the line for an accurate measurement.
Step 5
Why is it preferable to use a filler (labelled B in the diagram) rather than your mouth when filling A?
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It is preferable to use a filler rather than your mouth because the caustic solution (NaOH) can be harmful if swallowed and may cause the risk of infection transfer.
Step 6
State one precaution you would take when transferring the liquid measured in A to the titration flask to ensure that the correct volume was transferred.
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One precaution to take when transferring the liquid is to allow the pipette to drain freely under gravity, ensuring that no drop remains at the tip of the pipette.
Step 7
Name a suitable indicator for this titration. What colour change was observed in the titration flask at the end point?
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A suitable indicator for this titration is methyl orange. The colour change observed in the titration flask at the end point is from yellow to red (or pink).
Step 8
The balanced equation for the titration reaction:
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The balanced equation for the titration reaction is:
ightarrow ext{NaCl} + ext{H}_2 ext{O}$$
Step 9
Calculate the concentration of the sodium hydroxide solution in moles per litre.
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Using the formula for concentration, we can calculate the concentration of the sodium hydroxide solution as follows:
