I am struggling with this problem about a magnesium reaction

Question

Can you help me with this problem about a magnesium metal reaction?
Magnesium metal is reacted with excess HI to produce hydrogen gas. The gas is collected over water. 45.82mL of the wet hydrogen gas is collected at 30.0°C. The water level in the eudiometer is equalized with water in another vessel before the volume of H2 gas is determined. The atmospheric pressure in the laborotory is 0.972 atm.

A. What is the vapor pressure of water under these conditions?

B. What is the partial pressure of the H2 gas

C. What mass of Mg metal was consumed, assuming 100% yield

Answer 1

A.  You will need to look up the vapor pressure of water at the given temperature.  My text gives me: 31.8 torr

B.  Atmospheric pressure equals pressure due to H₂ and H₂O.  

• Convert 31.8 torr to atm
• Subtract that pressure (H₂O vapor at 30°C) from the given barometric pressure (see a previous response from JRS regarding a similar question to this part of the calculation for the math)

C. Determine moles of H₂ gas produced using ideal gas law

    Using the moles of H₂, and the balanced reaction, determine the moles of Mg reacted

    Lastly, convert moles of Mg to grams