K.C.S.E Physics Q & A - MODEL 2011PP1QN17

K.C.S.E Physics Q & A - MODEL 2011PP1QN17

​(a) When the temperature of water reaches the boiling point, bubbles rise to the surface.
(î) State what is contained in the bubbles. 
(ii) State the reason why bubbles rise to the surface only at the boiling point.
(b) Figure 14 shows a graph of vapour pressure against the temperature of water vapour, in a laboratory where a mercury barometer indicates a height of 61.8 cm.

(b) (i) Determine the atmospheric pressure in the laboratory in Nm^-2.
(Take g = 10m/s² and density of mercury = 13600 kg/m³).
(ii) Use the graph to determine the boiling point of water in the laboratory.
(c) In an experiment to determine the specific heat capacity of a metal, a 100g of the metal was transferred from boiling water to a lagged copper calorimeter containing cold water. The water was stirred and a final steady temperature was realized. The following data was recorded.
Initial temperature of cold water and calorimeter = 20°C.
Temperature of boiling water = 99°C.
Final temperature of water, calorimeter and the metal = 27.7°C.
Mass of cold water and calorimeter = 130g.
Mass of calorimeter = 50g.
(Take specific heat capacity of water as 4200Jkg^-1K^-1)
(Specific heat capacity of copper as 400Jkg^-1K^-1).
Use the data to determine:
(i) the heat gained by the water and the calorimeter;
(ii) the specific heat capacity of the metal.
(d) State one possible source of error in the value of the specific heat capacity obtained in the experiment.

answers