K.C.S.E Physics Q & A - MODEL 2019PP1QN16

K.C.S.E Physics Q & A - MODEL 2019PP1QN16

​(a) State the meaning of the term “heat capacity.” 
(b) State how pressure affects the melting point of a substance. 
(c)Figure 7 shows a set tip of apparatus that may be used to apparatus the specific latent heat of  vaporization of steam

​(I) Describe how the mass of condensed steam is determined. 
(ii) Other than mass and time, state two other measurements that should be taken during the experiment. 
(iii) Show how the measurements in (c)(ii) can be used to determine the specific latent heat of vaporization of water.
(iv) State the precaution that should be taken so that the mass of the condensed steam measured  corresponds to the actual mass of steam collected during the time recorded  in the experiment
(v) State  why it is not necessary to measure temperature in in the set up 

answers

​(a) Heat capacity is the quantity of heat energy required to raise the temperature of a substance by 1K. 
(b) - Increase in pressure lowers the melting point while decrease in (1 mark) pressure raises/increases the melting point. 
(c) (i) - Measure the mass of the empty beaker M1.  
 Measure the mass of the beaker plus the condensed steam M2 
 Get the difference between the two masses (M2 —M1) = M 
(ii) - Voltage 
 Current 

​(iv) - Start timing when the steam drops start forming out steadily and Stop immediately the beaker is withdrawn. 
(V) Steam is produced at boiling point where temperature is constant.