To calculate the volume of gas formed in the reaction between excess copper (Cu) and 16.0 mol/dm^3 of a substance with the formula HN4 (assuming it's ammonium hydride, NH4), we need to first write and balance the chemical equation for the reaction.
The balanced chemical equation for the reaction between copper and ammonium hydride is:
Cu + 2NH4 → Cu(NH4)2
Now, we can use stoichiometry to find the volume of gas formed. We know that 1 mole of any gas occupies 24.45 dm^3 at standard temperature and pressure (STP), which is 0°C (273 K) and 1 atm pressure.
1 mole of Cu(NH4)2 produces 2 moles of NH4 gas.
So, for every mole of Cu(NH4)2 that reacts, we get 2 moles of NH4 gas.
Given that you have 16.0 mol/dm^3 of NH4, you can find the moles of Cu(NH4)2 that reacted:
Moles of Cu(NH4)2 = (16.0 mol/dm^3) / 2 = 8.0 mol/dm^3
Now, we can use the Ideal Gas Law to find the volume of NH4 gas formed at STP:
PV = nRT
Where:
P = pressure (1 atm at STP)
V = volume (unknown)
n = moles (8.0 mol/dm^3)
R = ideal gas constant (0.0821 L.atm/mol.K)
T = temperature in Kelvin (273 K at STP)
Now, plug in the values and solve for V:
V = (nRT) / P
V = (8.0 mol/dm^3 * 0.0821 L.atm/mol.K * 273 K) / 1 atm
V = 183.12 L
So, the volume of NH4 gas formed at STP is approximately 183.12 liters.