C3 Analysis

Question 1

What happens when dilute acids are added to metal carbonate powders or solutions?

Answer 1

Carbonates react with dilute acids to form bubbles of carbon dioxide.

Question 2

How would you prove the identity of the compoundwhen dilute acids are added to metal carbonate powders or solutions

Answer 2

Carbon dioxide produces a white precipitate with limewater. This turns limewater milky.

Question 3

How would you test for the presence of halide ions in solution?

Answer 3

Halide ions in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid.

Question 4

How would you measure the volumes of a strong acid and alkali reacting together?

Answer 4

By titration. The alkali is pipetted into a conical flask. A suitable indicator is added. The acid is added carefully from a burette until the indicator shows that the solution is just neutralised.

Question 5

If you know the concentration of the alkali, how would you find the concentration of the other reactant?

Answer 5

the results of a titration can be used to find the concentration of the other reactant.

Question 6

When 25cm³ of 0.1mol dm^-3 NaOH were titrated with 20cm³ of HCl. Find the concentration of the HCl.

Answer 6

HCl + NaOH → NaCl + H2O

Number of moles= 0.1x0.025 = 0.0025 moles of NaOH.

So 1:1 ratio of HCl:NaOH

So 0.0025 moles of HCl used

Concentration=0.0025/0.02

= 0.125 mol dm^-3

Question 7

If you had no indicator, what device could you use to measure the pH?

Answer 7

A pH meter or a pH sensor on a data-logger.