cameroon gce A level June 2023 chemistry 2

cameroon gce A level June 2023 chemistry 2

cameroon gce A level June 2023 chemistry 2

SECTION A: PHYSICAL AND GENERAL CHEMISTRY
1. (a) Define
( i) a chemical bond.
(ii) State and explain the shapes of the following molecules:
NH3
BC13 r
(5 marks)
(b) Sodium-23 decays through p-emission and has a half-life of 12 days,
(i) What is meant by half life?
(ii) Write a balanced nuclear equation for the P-emission of sodium -23.
(Hi) Calculate the mass that remains when a 1.25 g sample of sodium undergoes decay for 60 days.
(4 marks)
23/0715/2 Go on to the next page3
In an experiment to determine the molar mass of a volatile liquid, 1.715 g of a liquid was vapourized at 40°C
and 2 atm releasing 488 cm3 of vapour.
State the experimental method used in the determination of the molar mass of the liquid.
(c)
(i)
(ii) Calculate the molar mass of the liquid. (R = 0.082 atm dm3 K’1 mol’1).
r
i i
(3 marks)
‘ ’ .- • – • l’:; 7 • . • IV . .• .K,1 ‘ i J.f i ’.
(d) Potassium chlorate (V), KC103 decomposes in the presence of manganese (IV) oxide catalyst to release oxygen.
(i) Write out a balanced equation for the decomposition of the chlorate. . » A *
(ii) Calculate the volume of oxygen produced (measured at stp) for the decomposition of 0.73 g of KCIO3.
}
. V-
(3 marks)
An ideal mixture contains 0.85 moles of methanol and 0.42 moles of ethanol. If the vapour pressure of pure
methanol and pure ethanol at 20 °C are 98 mmHg and 43.6 mmHg respectively.
Calculate:
I
(e)
I
(0 The mole fraction of each component in the mixture.
(ii) The partial pressure of each component