Question: Is the number of molecules in the reactants of a balanced chemical equation always equal to the number of molecules in the products? Explain your answer.

When a chemist collects hydrogen gas over water, she ends up with a mixture of hydrogen and water vapor in her collecting bottle. if the pressure in the collecting bottle is 97.1 kilopascals and the vapor pressure of the water is 3.2 kilopascals, what is the partial pressure of the hydrogen?