Lesson 4: The Combined Gas Law
 The combined Gas Law
-
Boyle’s Law, Charles’s Law and Gay-Lussac’s Law can be combined to give the combined gas law:
P1V1
=
T1
P2V2
T2
Try page 542 # 2, 3, 7
 Avogadro’s Law
In 1811, Avogadro hypothesized that equal volumes of all ideal gases at the same Temperature and
Pressure, contain the same number of molecules.
n1/V1 = n2/V2
This fits with our KMT view of gases – the space between gas atoms/molecules is so great, relative to
the size of the atoms, that their relative size does not matter.
This means that ONLY for gases, the volume is proportional to the moles
Ex.
CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g)
1L
2L
___
_____
 Molar Volume of Gases
According to Avogadro’s law, the volume of 1 mol of ANY gas will be the same. Scientists record this
value for 2 special conditions:
 At Standard Temperature and Pressure (STP) (273.15 K; 101.325 kPa) = 22.4 L/mol
 At Standard Ambient Temperature and Pressure (SATP) (298.15 K, 100 kPa) = 24.8 L/mol
Try page 550 #2, 3, 5, 7, 9, 11, 12, 13
Lesson 4 – The Combined Gas Law
Learning Intention
5. solve quantitative problems by performing calculations based on Boyle’s law, Charles’s law, Gay-Lussac’s law, the combined gas law, Dalton’s
law of partial pressures, and the ideal gas law
6. Explain Dalton’s law of partial pressures, Boyle’s law, Charles’s law, Gay-Lussac’s law, the combined gas law, and the ideal gas law
7. Explain Avogadro’s hypothesis and how his contribution to the gas laws has increased our understanding of the chemical reactions of gases
Uni/Multistructural
Relational
Extended Abstract
State the Combined and Avogadro’s law mathematically and in words
Define STP and SATP
Solve molar volume questions using Avogadro’s law
Solve questions using the combined gas law
Use the KMT to explain the laws
Predict how to calculate the molar mass of an unknown gas using Avogadro’s law and
molar volume
Create an analogy to explain the Laws to a small child who is young
Success Criteria
Uni/Multistructural
Relational
Extended Abstract
I can state the Combined and Avogadro’s law mathematically and in words
I can define STP and SATP
I can solve molar volume questions using Avogadro’s law
I can solve questions using the combined gas law
I can use the KMT to explain the laws
I can predict how to calculate the molar mass of an unknown gas using Avogadro’s law
and molar volume
I can create an analogy to explain the Laws to a small child who is young