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.

Question

Chemistry

Ronald

8 January, 13:15

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.

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Answers (1)

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Barbara Clayton · Answer 1

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.