Answer:
4.4 g
Step-by-step explanation:
Step 1: Write the balanced equation
Cu + 4 HNO₃ ⇒ Cu(NO₃)₂ + 2 NO₂ + 2 H₂O
Step 2: Calculate the moles corresponding to 3.2 L of NO₂ at STP
At standard temperature and pressure, 1 mole of NO₂ occupies 22.4 L.
3.2 L × 1 mol/22.4 L = 0.14 mol
Step 3: Calculate the moles of Cu needed to produce 0.14 moles of NO₂
The molar ratio of Cu to NO₂ is 1:2. The moles of Cu needed are 1/2 × 0.14 mol = 0.070 mol.
Step 4: Calculate the mass corresponding to 0.070 moles of Cu
The molar mass of Cu is 63.55 g/mol.
0.070 mol × 63.55 g/mol = 4.4 g