When a volume of h2 reacts with an equal volume of cl2 (assume you have 1 l of each) at the same temperature and pressure, what volume of product having the formula hcl is formed?
question 4 answers

The volume of H₂ times two

Explanation:

The reaction that takes place is:

Under the assumption that the gases behave ideally, then the moles of H₂ and Cl₂ are the same, because they have the same volume, temperature and pressure.

We can use the formula PV=nRT to solve this problem. For now let's say the temperature is 293 K, the volume is 1 L and the pressure is 1 atm. The values themselves are not important, just the fact that T and P remain constant is.

1 atm * 1 L = xmol * 0.082 atm·L·mol⁻¹·K⁻¹ * 293 K

xmol= 0.0416 mol

Finally we calculate the volume of HCl using PV=nRT:

1 atm * xL = 0.0832 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 293 K

xL = 2 L

So the volume of HCl is the volume of H₂ times two.