Question

Sodium metal reacts with water to produce hydrogen gas according to the following equation: 2Na(s) + 2H2O(l)2NaOH(aq) + H2(g) The product gas, H2, is collected over water at a temperature of 20 °C and a pressure of 754 mm Hg. If the wet H2 gas formed occupies a volume of 8.77 L, the number of moles of Na reacted was mol. The vapor pressure of water is 17.5 mm Hg at 20 °C.

Answer 1

Answer:

Number of moles of sodium reacted = 0.707 moles

Explanation:

P(H₂) = P(T) – P(H₂O)

P(H₂) = 754 – 17.5 = 736.5 mm Hg

Use the ideal gas equation which

PV= nRT, where P is the pressure V is the volume, n is the number of moles R is the Gas Constant and T is temperature

Re- arrange to calculate the number of moles and using the data provided

n = P x V/R x T

n =736.5 x 8.77/62.36367 x (mmHg/mol K) x (20 + 273)

n = 0.35348668

n = 0.353 moles H₂

from the equation we know that

0.353 mole H₂ x 2mole Na/1mole H₂, So

0.353 x 2 = 0.707 mole Na

The number of moles of Sodium metal reacted were 0.707 moles.