CHEMISTRY| MOLE CONCEPT | Question 30
The equation below shows the reaction the reaction between heated copper (II) oxide and ammonia gas.
3CuO(g) + 2 NH3(g) → 3Cu(S) + N2(g) + 3H2O(l)
If 20g of copper (II) oxide reacted with ammonia gas at STP.
Calculate;
a. The number of moles of copper (II) oxide used.
b. The volume of ammonia gas used.
c. The mass of copper formed.
(Cu = 64, 0 = 16, N = 14, H = 1. Molar volume of a gas at STP = 22.4 dm3)
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Data
Mass of copper (CU) = 20g
Molar volume at STP = 22.4dm3/mole
Asked
i. The number of mole of CuO
ii. Volume of ammonia gas used
iii. The mass of copper formed
The chemical equation for the reaction
3CUO(s) + 2NH3(s) →3Cu(s) + N2(s) + 3H2O(l)
3 moles: 2 moles: 1 mole: 3 moles
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A. To calculate the number of mole CuO
Mole = mass / Molar mass of CuO
= 20g / 80g/mole
= 0.25 mole
0.25 mole of copper (II) Oxide was reacted with ammonia -
B. To calculate the volume of ammonia
From the equivalent between CuO and NH3
3 moles of CUO Ξ 2moles of NH3
0.25 mole of CuO Ξ ?? of NH3
= (0.25 mole × 2 moles) / 3 moles
= 0.167 mole of NH3
To convert 0.167 mole into volume
Mole = volume / Molar volume
Volume = mole × molar volume
= 0.167 mole × 22.4dm3/mole
= 3.73dm3
73dm3 of ammonia was reacted with CuO -
C. To calculate the mass of Cu formed
From mole equivalent between CuO and Cu 3 moles of CuO Ξ 3 moles of Cu
0.25 moles of CuO Ξ ?? of Cu
= (0.25 moles × 3 moles) / 3
= 0.25moles
O.25 moles of Cu was formed.
To convert 0.25 mole into mass
Mass = mole × molar mass
= 0.25 mole × 64
= 16g
16g of coper (Cu) was formed
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