A piece of sodium metal undergoes complete reaction

withwater.

a. Write the complete balanced equation governing

thisreaction.

b. The hydrogen gas generated is collected over water

at25.0*C. The volume of the gas is 246 mL measured at 101.3kPa.

Calculate the number of grams of sodium used in thereaction.

(a) Equation of reaction:

2Na + 2H20 = 2NaOH + H2

(b) 0.46g of sodium was used in the reaction

Explanation:

(a) 2 moles of sodium reacted with 2 moles of water to yield 2 moles of sodium hydroxide and 1 mole of hydrogen gas

(b) mass of hydrogen gas produced (m) = PVM/RT

P = 101.3kpa = 1atm, V = 246mL = 246cm^3, M = 2g/mol, R = 82.057cm^3. atm/gmol. K, T = 25°C = 25+273 = 298K

m = (1*246*2) / (82.057*298) = 0.02g of hydrogen gas

From the equation of reaction

2 moles (46g) of sodium produced 1 mole (2g) of hydrogen gas

0.02g of hydrogen gas was produced by (46*0.02) / 2 = 0.46g of sodium