Question

What quantity of copper oxide will react with 2.80 litre of hydrogen at STP ?

Answer 1

22.4 litres of cupric oxide will be formed with 2.80 litres of hydrogen at STP

Answer 2

The reaction between copper oxide and hydrogen is a redox reaction. The reaction takes place according to the following equation: 

       CuO + H₂  --------------> Cu  +  H₂O

The mole ratio between CuO : H₂  is 1:1

---------------------------------------------------------------------------------------------------------

Find the moles of 2.80 liters of hydrogen using ideal gas law

According to the ideal gas law, 1 mole of an ideal gas occupies exactly 22.4 liters by volume. 

If 22.4 liters = 1 mole 
Then 2.8 liters = 1 × 2.8/22.4
                        = 0.125 moles

---------------------------------------------------------------------------------------------------------

since mole ratio in the equation is 1:1 between copper oxide and hydrogen

Then the moles of CuO that will react with o.125moles of hydrogen will also be 0.125 moles

-----------------------------------------------------------------------------------------------------------

Calculate the mass of CuO that corresponds to 0.125 moles

mass  = moles × molar mass

molar mass of CuO = 79.5

moles = 0.125

Mass = 0.125 × 79.5

         = 9.9375 g

The mass of CuO that reacts with 2.8 liters of hydrogen is 9.9375 g