chemistry
posted by Riana .
peice of sodium metal reacts with water. 246ml volume of hydrogen gas was collected over water at 25 celsius and at an atmospheric pressuric pf 101.3 kpa.
what was the pressure of dry hydrogen?
what is the mass of sodium used up by the reaction?

2Na + 2H2O ==> H2 + 2NaOH
Ptotal = pH2 + pH2O
Ptotal = 101.2 kPa
pH2O = look up vapor pressure H2O at 25 C. Substitute and solve for pH2. That will be pressure of dry H2.
Use PV = nRT and solve for n. Use dry H2 for P. If you use 101.3 then use 8.314 for R. Remember T must be in kelvin. Solve for n.
Then convert mols H2 to mols Na (from the equation) and convert to grams Na used. g = mols x atomic mass. 
is the dry hydrogen 98.13kpa?
and is the mass 224.1g?