What is the mass in grams of 10l of methane at stp

To answer this item, it is assumed that methane behaves ideally such that it follows the equation,
  
    PV = nRT

where P is pressure, V is volume, R is the universal gas constant, and T is temperature. Solving for the value of n,

      n = PV / RT

At STP condition, T is equal to 0°C (273.15 K) and P is equal to 1 atm. Substituting the known values,

     n = (1 atm)(10 L) / (0.0821 L.atm/mol.K)(273.15 K)

        n = 0.446 mol

Then, multiply the number of moles by the molar mass of methane, 16 g/mol.

      M = (0.446 mol)(16 g/mol) = 7.13 g

ANSWER: 7.13 g