# The diagram below shows a set-up that can be used to obtain nitrogen gas in an experiment.

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The diagram below shows a set-up that can be used to obtain nitrogen gas in an experiment.

1.
1. Name liquid L
2. What observation would be made in tube K after heating for some time?
3. Write an equation for the reaction that took place in tube K.
4. If 320cm3 of ammonia gas reacted completely with the copper?
Calculate:
1. Volume of nitrogen gas produced. (1mk)
2. the mass of copper oxide that reacted (3mks)
(Cu = 63.5, O=16.O, one mole of gas occupies 24 litres at room temperature and pressure)
5. At the end of experiment the PH of the water in the beaker was found to be about 2. Explain.

1. Liquid L- water
2. Black Copper (II) Oxide changes to brown Copper metal
3. 2CuO(s) + 2NH3(g) → 3Cu(s) + 3H2O(l) +N2(g)
4.
• 2×24litres of NH3 produce 24litres N2
48000cm3 NH3 produce 24000cm3 N2
∴ 320cm3 NH3 produce   320  × 24000cm3 N2
48000
=160cm3 N2
• 2 Moles NH3 produce 3 moles CuO
48000cm3 NH3 produce 238.5g CuO
∴ 320cm3 NH3 produce   320  × 238.5g CuO
48000
=1.59g
5. Ammonia dissolved in the water to form ammonia solution which is a weak base.