required practicals

Question 1

sodium carbonate reacts with hydrochloric acid in an exothermic reaction. plan a method to investigate the effect of changing the mass of sodium carbonate powder on the highest temperature reached (6 marks)

Answer 1

• measure volume of hydrochloric acid with a measuring cylinder
• pour acid into a polystrene cup
• measure the intial tmep of the acid with a thermometer
• add a known mass of sodium carbonate
• measure this with a balance and stir
• measure the highest temp reached
• repeat with different masses of sodium carbonate
• repeat the whole investigation

Question 2

The higher the concentration of a sample of dilute sulfuric acid, the greater the volume
of sodium hydroxide needed to neutralise the acid.
The student tested two samples of dilute sulfuric acid, P and Q.
Describe how the student could use titrations to find which sample, P or Q, is more
concentrated. (6)

Answer 2

measure the volume of acid
* add indicator to the acid
* add sodium hydroxide solution
* until the colour changes
* record volume of sodium hydroxide solution added
* repeat procedure with the other acid