The table below gives the volume of hydrogen gas produced when different acids of 50cm3 were each reacted with 10cm piece of magnesium ribbon in a conical flask.
a) On the grid provided, plot on the same axis, the graph of volume of gas produced against time (4mks)
In the graph plotted ; Award marks as follows:
b) From the graph, determine the rate of reaction of both acids at 55 seconds
i) 1M sulphuric (VI) acid (1mk)
Rate of 1M H2SO4 = 0.5 ± 0.05
ii) 1M ethanoic acid (1mk)
Rate of 1M ethanoic acid = 0.25 ± 0.01
c) The rate of reaction of H2SO4 is twice that of ethanoic acids. This is because H2SO4 is stronger while ethanoic acid is a weak acid.
c) Explain the difference in the rate of evolution of the gas as determined in (b) above (2mks)
d) Calculate the number of moles of hydrogen gas produced when 10cm magnesium ribbon is completely reacted with 1M sulphuric (VI) acid. (Molar gas volume = 24dm3 at r.t.p) (2mks)
e) What mass of magnesium had therefore reacted? (Mg = 24) (2mks)
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