Question

# Aluminum reacts with aqueous sodium hydroxide to produce hydrogen gas according to the following equation: 2Al(s)...

Aluminum reacts with aqueous sodium hydroxide to produce hydrogen gas according to the following equation: 2Al(s) + 2NaOH(aq) + 6H2O(ℓ) 2NaAl(OH)4(aq) + 3H2(g) In an experiment, the H2 gas is collected over water in a vessel where the total pressure is 758 torr and the temperature is 20°C, at which temperature the vapor pressure of water is 17.5 torr. Under these conditions, the partial pressure of H2 is __torr. If the wet H2 gas formed occupies a volume of 9.60 L, the number of moles of H2 formed is mol.

According to dalton's law total pressure of gas is equal to sum of partial pressure exerted by each individual gas

Ptotal = P1 + P2 + P3

Phyrogen = Ptotal  - PH2O

substitute value

PHydrogen = 758 - 17.5 = 740.5 torr

Pressure of H2 = 740.5 torr

Use ideal gas equation for calculation of mole of gas

Ideal gas equation

PV = nRT             where, P = atm pressure= 740.5 torr = 0.9743 atm,

V = volume in Liter = 9.60 L

n = number of mole = ?

R = 0.08205L atm mol-1 K-1 =Proportionality constant = gas constant,

T = Temperature in K = 200C = 273.15+ 20 = 293.15 K

We can write ideal gas equation

n = PV/RT

Substitute the value

n = (0.9743 X9.60) / (0.08205X 293.15) = 0.38886 mole

0.38886 mole of H2 produced.

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