Weighing Gases Lesson 8. The electrolysis of water is used to generate 0.250 g of H 2 (g) . If the hydrogen was generated at a rate of 1.500 amps over a period of 4.46625 hours , calculate Avogadro’s number (the number of atoms of H in 1 gram )
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Weighing GasesLesson 8
The electrolysis of water is used to generate 0.250 g of H2 (g). If the hydrogen was generated at a rate of 1.500 amps over a period of 4.46625hours, calculate Avogadro’s number (the number of atoms of H in 1 gram)
1 amp is defined as the number of coulombs per second.
There are 6.24 x 1018 electronsin a coulomb.
It takes 1 electronto make 1 H atom
x 60 min
x 60 s
x 1.500 coul
x 6.24 x 1018 el
x 1 at H
= 1.505 x 1023 at H
= 6.02 x 1023 at H
If you weigh the volumes
1.0 L of CO2
Avogadro’s hypothesis states that equal volumes of gases have the same number of
1.0 L of H2
Note that the mass ratio is the same as the molar mass ratio
A volume of an unknown gas weighs 0.563 g. An equal volume of H2 gas weighs
0.01774 g. Calculate the molar mass of the unknown gas.
= 0.563 g
x 2.02 g/mole
= 64.1 g/mole
This means the molar mass of gas X is 31.7 x heavier than H2
If the gas is a byproduct of burning coal and causes acid rain, what is the gas?
x 30.06 g/mole
= 4.02 g/mole
= 2.365 g
A volume of an unknown gas weighs 2.365g. An equal volume of C2H6 (ethane) gas
weighs 17.7g. Calculate the molar mass of the unknown gas.
This means the molar mass of gas X is 0.1336 x C2H6
If the unknown gas is an element, what gas is it?
Rock me Avogadro