How many grams of cah2 are needed to generate 145 l of h2 gas if the pressure of h2 is 825 torr at 22 ∘c?

To solve this problem, we must first assume that CaH2 acts like an ideal gas so that we can use the ideal gas equation:

P V = n R T

where,

P = pressure = 825 torr

V = volume = 145 L

n = number of moles = unknown

R = universal gas constant = 62.36367 L Torr / mol K

T = absolute temperature = 22°C = 295.15 K

Finding for n:

n = P V / R T

n = (825 torr) (145 L) / (62.36367 L Torr / mol K * 295.15 K)

n = 6.5 mol

Molar mass of CaH2 is 42.1 g/mol, therefore the mass is:

mass CaH2 = (6.5 mol) (42.1 g/mol)

mass CaH2 = 273.65 g