3- Physical Chemistry

Question 1

Calorimetry General

Answer 1

Used for dissolving, displacement, or neutralisation reactions

To prevent energy loss, use polystyrene cups in a beaker of cotton wool, and use a lid to prevent evaporation

Question 2

Calorimetry- neutralisation

Answer 2

Hydrochloric acid and sodium hydroxide (separate beakers)

In a water bath at 25C

Put in polystyrene cup with lid

Record temp every 30 s up to highest temp

Question 3

Calorimetry- combustion

Answer 3

Heat water

Use draughts eg heat proof mat as a screen to minimise heat loss

Put 50 g water in metal (copper as good conductor) container

Record temp

Weight spirit burner and lid

Stir until 50C

Weight again

Calculate enthalpy change

Question 4

Decomposition of hydrogen peroxide

Answer 4

Forms water and oxygen

Use gas syringe ( collect oxygen)

Comparing catalysts:

Calculate time take for different metals (as catalysts) to produce a certain amount of oxygen, measure volume in a certain time

Question 5

Reversible reaction- ammonium hydroxide

Answer 5

White solid Breaks down into ammonia gas and hydrogen chloride gas

When cools it reforms a white solid