Cu + O2 --Cu2O a. Write the balanced equation for this reaction.
b. How many grams of Cu are needed to produce 300. grams of Cu2O?
c. How many grams of Cu2O can be produced from 8.0 L of O2 at STP?

a. 4Cu + O₂ → 2Cu₂O

b. 266g Cu

c. 102g Cu₂O

Explanation:

Based on the balanced reaction:

a. 4Cu + O₂ → 2Cu₂O

4 moles of Cu reacts per mole of oxygen to produce 2 moles of Cu₂O.

b. To solve this question we need to find the moles of Cu₂O. With these moles and the balanced reaction we can find the moles of Cu and its mass:

Moles Cu₂O -Molar mass: 143.09g/mol-

300g Cu₂O * (1mol / 143.09g) = 2.097 moles Cu₂O

Moles Cu:

2.097 moles Cu₂O * (4mol Cu / 2mol Cu₂O) 4.193 moles Cu

Mass Cu - Molar mass: 63.546g/mol-

4.193 moles Cu * (63.546g / mol) = 266g Cu

c. In the same way, using PV = nRT we can find the moles of Oxygen. With the moles of oxygen we can find the moles of Cu₂O and its mass:

n = PV / RT

P = 1atm at STP, V = 8.0L, R = 0.082atmL/molK, T = 273.15K at STP:

n = 1atm*8.0L / 0.082atmL/molK*273.15K

n = 0.357 moles O₂

Moles Cu₂O:

0.357 moles O₂ * (2mol Cu₂O / 1mol O₂) = 0.714 moles Cu₂O

Mass Cu₂O -Molar mass: 143.09g/mol-

0.714 moles Cu₂O * (143.09g/mol) =

102g Cu₂O