The oxidation state of N is
B.+5
The density of a glass helps determine the weight of the optical assembly and, along with lens diameter, becomes critical for weight sensitive applications.
We get the pressure of the hydrogen gas from the difference between the measured pressure and the vapor pressure of water:
total pressure = Pressure of H2 + Vapor Pressure of H2O
1.00 atm = Pressure of H2 + 0.0313 atm
Pressure of H2 = 1.00 atm - 0.0313 atm = 0.9687 atm
From the ideal gas law,
PV = nRT
we can calculate for the number of moles of H2 as
n = PV/RT = (0.9687 atm)(0.246L) / (0.08206 L·atm/mol·K)(298.15 K)
= 0.00974 mol H2
where
V = 246 mL (1 L / 1000 mL) = 0.246 L
T = 25 degrees Celsius + 273.15 = 298.15 K
We use the mole ratio of Na and H2 from the reaction of sodium metal with water as shown in the equation
2Na(s) + 2H2O(l) → 2 NaOH(aq) + H2(g)
and the molar mass of sodium Na to get the mass of sodium used in the reaction:
mass of Na = 0.00974 mol H2 (2 mol Na /1 mol H2)(22.99 g Na/1 mol Na)
= 0.448 grams of sodium
