A 0.50 g mixture of Cu and CuO was treated with hydrogen at elevated temperature. CuO was

reduced to Cu .

(b) Before the experiment, calculate the minimum amount (in mole) of hydrogen required
to ensure the reduction is completed. (3 marks)
(c) After passing with in excess amount of hydrogen gas, 0.42 g of solid remained.
Calculate the percentage of CuO in the mixture.

I wonder what part a to the question was. You can't do part b without doing part c first.

c.
(1) g Cu + g CuO = 0.5g
(2) g Cu + g Cu + g O = 0.5 g
After heating the O is gone so subtract (2) from (1) to get
g O = 0.5-0.42 = 0.08

The reduction equation is
2H2 + O2 ==> 2H2O
mols O2 = 0.08/32 = 0.0025
mols H2 = 2*0.0025 = 0.005

For percent CuO, you need to know how much CuO was in the original 0.5 g sample.
CuO + H2 ==> Cu + H2O
You know 0.005 mols H2 required which means 0.005 molsCuO initially. Convert to grams CuO, then to % CuO in the original sample.

Part (A) is just balance the equation that I had done it.

the answer is what you had thought

To answer part (b) of the question, we need to calculate the minimum amount of hydrogen required to ensure complete reduction of CuO to Cu.

1. Begin by calculating the number of moles of Cu and CuO in the 0.50 g mixture.
- The molar mass of Cu is 63.55 g/mol.
- The molar mass of CuO is 79.55 g/mol.

Number of moles of Cu = mass of Cu / molar mass of Cu
= 0.50 g / 63.55 g/mol

Number of moles of CuO = mass of CuO / molar mass of CuO
= 0.50 g / 79.55 g/mol

2. Since CuO is being completely reduced to Cu, we only need to consider the moles of CuO for the reaction.

3. For complete reduction, one mole of CuO requires one mole of hydrogen gas (H2) according to the balanced chemical equation:
CuO + H2 -> Cu + H2O

4. Therefore, the minimum amount of hydrogen required is equal to the number of moles of CuO.

Now let's move on to part (c) of the question.

To determine the percentage of CuO in the mixture, we need to calculate the amount of CuO that reacted and the amount of CuO that remained unreacted.

1. Calculate the number of moles of CuO that reacted:
- The initial moles of CuO = mass of CuO before reaction / molar mass of CuO
- The moles of CuO that reacted = initial moles of CuO - moles of CuO that remained

2. Calculate the mass of CuO that remained:
- Mass of CuO that remained = moles of CuO that remained * molar mass of CuO

3. Calculate the percentage of CuO in the mixture:
- Percentage of CuO = (mass of CuO that remained / mass of initial mixture) * 100

Keep in mind to convert grams to moles using molar mass and apply stoichiometry principles when balancing reactions and calculating moles of substances involved.