Hydrogen gas reacts with chlorine gas according to

CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance

Problem

\mathrm{H_2(g) + Cl_2(g) \rightarrow 2HCl(g)}

. One litre of hydrogen at

300\,\text{K}

and

1.013\times10^{5}\,\text{Pa}

is mixed with an equal volume of chlorine at the same conditions in a closed vessel so that the reaction proceeds to completion and the system returns to

300\,\text{K}

. (a) Using the stoichiometry of the reaction, derive the ratio of moles of reactants consumed to products formed. (b) Calculate the total number of molecules present in the vessel after reaction completion, assuming the reaction goes to

100\%

yield and the volume of the vessel remains constant. (c) The vessel is now heated to

500\,\text{K}

while the pressure is allowed to rise freely. Determine the final pressure in the vessel. (d) Comment on whether the total pressure after heating depends on the identity of the gas or solely on the total number of molecules.

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