C7.5 Quantitative analysis by titration

Question 1

16. What are the main stages of a quantitative analysis?

Answer 1

1- measuring out accurately a specific mass or volume of the sample
2- working with replicate samples
3- dissolving the samples quantitatively
4- measuring a property of the solution quantitatively
5- calculating a value from the measurements (IaS 1.4)
6- estimating the degree of uncertainty in the results (IaS 1.5–1.6)

Question 2

17. What can concentrations of solutions be measured in?

Answer 2

• g/dm3

Question 3

18. What is a standard solution?

Answer 3

-any solution you know the concentration of

Question 4

11. What is the process of an acid-alkali titration reaction when starting with a solution?

Answer 4

• put known volume of alkali into titration flask, with a couple of drops of indicator
• fill a burette with an acid
• drop acid from burette into alkali in titration flask, making sure to swirl to mix
• be slower towards the end point
• when indicator changes colour= alkali neutralised
• record volume of acid used to neutralise alkali

Question 5

11. How do you make titration accurate?

Answer 5

• make sure all equipment clean
• burette at eye level
• white paper under flask to see colour change
• same person make readings
• repeat titrations

Question 6

11. How do you do titration with a solid acid or alkali?

Answer 6

• crush it
• weigh it on balance
• add a solvent (e.g. water, ethanol) to dissolve powder
• swirl flask until dissolved