Concept explainers
91 A 0.2500-g sample of an Al-Zn alloy reacts with HCl to form hydrogen gas:
The hydrogen produced has a volume of 0.147 L at 25°C and 755 mm Hg. What is the percentage of zinc in the alloy?
Interpretation:
A 0.2500 g sample of an Al-Zn alloy reacts with HCl to form hydrogen gas:
The hydrogen produced has a volume of 0.147L at 250C and 755mm Hg. The percentage of Zinc in the alloy needs to be calculated.
Concept introduction:
An ideal gas which is known as the perfect gas is a gas whose volume V, Pressure P and temperature T are related through the ideal gas laws: -
Here,
-
n = Number of moles of the gas
R = Universal gas constant
T = Temperature
P = Pressure
Ideal gases are described as the molecules which have negligible size but have an average molar kinetic energy which is dependent on the temperature. When temperature is low most of the gases behave like ideal gases and the ideal gas law might be applied to them.
Answer to Problem 5.91PAE
Solution:
Explanation of Solution
Here given that,
Temperature = 250C;
Converting Temperature into Kelvin
Therefore, the temperature in Kelvin is 298 K
Pressure = 755 mm Hg = Converting mmHg to atm
Therefore, the Pressure in atm is 0.993 atm
The number of moles gas is calculated from ideal gas equation.
Total number hydrogen moles can be calculated by using an ideal gas equation: -
Here
R = Gas constant = 0.0821 L.atm / mol. K
T = Temperature = 298
V = Volume = 0.147 L
Total number of hydrogen moles comes by the combination of Al and Zn
Now, let’s assume mass of Al is x therefore, mass of Zn is (0.2500-x) g
Therefore,
Now the mass of Zn will be: -
Now, calculating the percentage of Zn by using below equation: -
Now substituting the value of Zn and alloy in the above equation: -
An ideal gas which is known as the perfect gas is a gas whose volume V, Pressure P and temperature T are related through the ideal gas laws: -
Here,
-
n = Number of moles of the gas
R = Universal gas constant
T = Temperature
P = Pressure
The above equation can be used to calculate the percentage of Zn in the alloy.
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Chapter 5 Solutions
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