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Aim
Aim
To find the concentration of a solution of hydrochloric acid
To find the concentration of a solution of hydrochloric acid
A. Report & Analyse of Results
A. Report & Analyse of Results
1. Record your results in a suitable table
Things to consider CPAC 4b
Things to consider CPAC 4b
CPAC 4b - Obtains accurate, precise and sufficient data for experimental and investigative procedures and records this methodically using appropriate units and conventions.
· Write down the exact burette value to 0.05cm3
· Measure masses to at least 2dp’s
· Obtain 2-3 concordant results
· Data recorded includes units
2. Calculate the mean titre using your two concordant results
3. Calculate the number of moles of sodium hydroxide that were contained in your mean titre.
4. Calculate the number of moles of hydrochloric acid that were contained in the full 250 cm3
5. of diluted hydrochloric acid.
5. Calculate the concentration of the original solution of hydrochloric acid
Learning Tip
Learning Tip
Do not include your rough titration when calculating your mean.
Give all burette readings to the nearest 0.05 cm3
Math skills that you will require
Math skills that you will require
Recognise and make use of appropriate units in calculations.
Recognise and use expressions in decimal and ordinary form.
Use an appropriate number of significant figures.
Find arithmetic means.
Understand and use the symbols: =, <, <<, >>, >, ∝, ~ and ⇌.
Change the subject of an equation.
Substitute numerical values into algebraic equations, using appropriate units for physical quantities.
B. Evaluate your report by answering the questions
B. Evaluate your report by answering the questions
1. Write a chemical equation for the reaction of hydrochloric acid with sodium hydroxide.
2. The pink colour seen at the end point fades because the excess sodium hydroxide reacts with carbon dioxide in the air. This reaction makes sodium carbonate.
(a) Write an equation for the reaction of sodium hydroxide with carbon dioxide.
(b) When sodium hydroxide solution is stored, it reacts with carbon dioxide in the air.
(i) How will this change the concentration of the sodium hydroxide solution?
(ii) How will this affect the volume of sodium hydroxide solution required to reach the end point in the titration? Explain your answer.
3. Explain why it is better to have a titre of around 25 cm3 than of around 10 cm3
C. Evaluate your Practical by Completing the Form - so you know where you should aim to make improvements in future
C. Evaluate your Practical by Completing the Form - so you know where you should aim to make improvements in future
Required Resources
Required Resources
Core Practical 3 Student Evaluation.docxConsult CLEAPSS Hazcards® 32,91A,47A. Perform a risk assessment using up-to-date information before this practical is carried out
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