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Aim
Aim
To make a solution of a known concentration of acid and use it to find the concentration of a solution of sodium hydroxide
To make a solution of a known concentration of acid and use it to find the concentration of a solution of sodium hydroxide
A. Report & Analyse of Results
A. Report & Analyse of Results
1. Record your results in a table similar to the following:
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 concentration of your sulfamic acid solution. The Mr of sulfamic acid is 97.1.
3. Calculate the mean titre using your concordant results.
4. Calculate the number of moles of sulfamic acid in your mean titre.
5. Calculate the concentration of the sodium hydroxide solution used.
Learning Tip
Learning Tip
Sulfamic acid is a monoprotic acid. One mole of sulfamic acid will react exactly with one mole of sodium hydroxide.
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. A 250 cm3 volumetric flask has an accuracy of +/– 0.6 cm3. Calculate the percentage uncertainty in the volume of the sulfamic acid solution in the volumetric flask.
2. Each burette reading is accurate to +/– 0.05 cm3. Calculate the percentage uncertainty in one of your titres.
3. Why should the pipette be rinsed with the sodium hydroxide solution after washing it with water?
4. Why is there no need to dry the conical flask after washing it out between trials?
5. Identify another indicator that could be used in this titration and state the colour change that would be seen at the end point.
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 2 Student Evaluation.docxAS-and-A-level-Chemistry-Core-Practical-2- student sheets.docxConsult CLEAPSS Hazcards® 98B, 91A & 32 . Perform a risk assessment using up-to-date information before this practical is carried out
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