Question

why is the vapor pressure of water important in this experiment?
select one:
the vapor pressure of water contributes to the humidity on the outside, so it must be accounted for only on high humidity days.
the trapped gas inside of the graduated cylinder is a mixture of water and butane.
the water vapor pressure is not important because the only gas inside the graduated cylinder is butane.
the vapor pressure of water is not important because we are measuring the air pressure.

Explanation:

When gas is collected over water (as in many experiments), the gas collected is a mixture of the desired gas (here, butane) and water vapor. Dalton's law of partial pressures states that the total pressure of a gas mixture is the sum of the partial pressures of each component. So, the vapor pressure of water (partial pressure of water vapor) must be considered as it is part of the gas mixture inside the graduated cylinder.

Answer:

The trapped gas inside of the graduated cylinder is a mixture of water and butane.