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
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 equipment A... show full transcript
Worked Solution & Example Answer: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 burette.
Step 2
Which of the two solutions is usually measured using the piece of equipment labelled A?
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Answer
The hydrochloric acid (HCl) solution is usually measured using the piece of equipment labelled A.
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 pipette.
Step 4
Describe the correct procedure for rinsing and filling A.
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To properly rinse and fill the burette:
Rinse the burette with distilled water followed by a small amount of the hydrochloric acid solution to prevent contamination.
Ensure the burette is held upright and the tap is closed before filling.
Fill the burette above the zero mark, then open the tap to allow the liquid to drain until the bottom meniscus is on the zero mark.
Step 5
Why is it preferable to use a filter (labelled B in the diagram) rather than your hand when filling A?
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Using a filter prevents contamination of the solution and ensures the liquid flows smoothly into the burette without spilling or introducing air bubbles.
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 is to allow the liquid to drain under gravity without touching the side of the flask to avoid liquid retention inside the burette.
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 at the end point was from yellow to red.
Step 8
The balanced equation for the titration reaction.
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The balanced equation for the titration reaction is:
extHCl+extNaOHightarrowextNaCl+extH2extO
Step 9
Calculate the concentration of the sodium hydroxide solution in moles per litre.
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To calculate the concentration, use the formula:
C1V1=C2V2
Substituting the values:
0.10extMimes27.5extcm3=C2imes25.0extcm3
Solving for C2 gives:
C_2 = rac{0.10 imes 27.5}{25.0} = 0.11 ext{ M}
Hence, the concentration of the sodium hydroxide solution is 0.11 M.
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