11.31 Gas Laws (Combined Reteach) Notes

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Gas Laws

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​Class Announcements:

• 8 days to makeup or retake exams!
  

School Announcements:

• May 15th Early Release

• Boyle's Law

• Charles’s Law

• Combined, Avogadro's, Ideal

• Dalton's Law Partial Pressures

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Standard Temperature and Pressure

STP
temperature of 0.00°C or 273 K and a pressure of 1.00 atm.

Multiple Choice

Standard temperature is defined as

• 0.0 K

• 273 K

• 273°C

Multiple Choice

Standard pressure is defined as

• 1.00 atm

• 870 mmHg

• 0.00 atm

Combined Gas law

The combination of Boyle's Law and Charles's Law is called the Combined Gas Law

Combined Gas law Variables

​	​Symbol	​Units
​Pressure	​P	​atm, Pa (kPa), torr, mmHg, Bar, psi, at
​Temperature	​T	​C converts to K
​Volume	​V	​L, mL, m3, cm3

​Temperatures in ^oC +273.15 = K
ALWAYS check that your units match!
If P₁ is in atm P₂ also needs to be in atm

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Key step Identifying Variables Combined Gas Law

• A helium balloon has a volume of 48.7 L at 37°C and 700 Pa . What Volume will it have at 970 Pa and 87^oC?

  • Step one Identify all the variables

    • V₁=

    • P₁=

    • T₁=

    • V₂=

    • P₂=

    • T₂=​

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Labelling

Identify the variables in the question.

Drag labels to their correct position on the image

P2

P1

T1

V1

V2

T2

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Don't Forget

Convert ^oC!!!
C + 273.15 = K

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Combined Gas Law

• A helium balloon has a volume of 48.7 L at 37°C and 700 Pa . What Volume will it have at 970 Pa and 87^oC?

  • Step one Identify all the variables

    • V₁= 48.7 L

    • P₁= 700 Pa

    • T₁= 37 ^oC +273.15 = 310.15 K

    • V₂= X

    • P₂= 970 Pa

    • T₂=​ 87 ^oC +​ 273.15 = 360.15 K

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Manipulate the original equation and plug in your values.

​Step 1

​Step 2

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​Step 3

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​Final EQ

plug in your variables.

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​Final EQ

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• V₁= 48.7 L

• P₁= 700 Pa

• T₁= 37 ^oC +273.15 = 310.15 K

• V₂= X

• P₂= 970 Pa

• T₂=​ 87 ^oC +​ 273.15 = 360.15 K

Multiple Choice

A helium balloon has a volume of 48.7 L at 37°C and 700 Pa . What Volume will it have at 970 Pa and 87^oC?

• 40.81

• 392664

• 1

Fill in the Blank

A gas takes up a volume of 17.0 liters, has a pressure of 2.30 atm, and a temperature of 299 K. If I raise the temperature to 350. K and lower the pressure to 1.50 atm, what is the new volume of the gas in liters? (tenths place __._ ) unit L

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Combined Gas Law

• The volume of a gas at 45°C and 0.678 atm is 180 mL. What Volume will it have at standard Temperature and a new volume of 79 mL?

  • Step one Identify all the information we have

    • V₁=

    • P₁=

    • T₁=

    • V₂=

    • P₂=

    • T₂=​

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Combined Gas Law

• The volume of a gas at 45°C and 0.678 atm is 180 mL. What Pressure will it have at standard Temperature and a new volume of 79 mL?

  • Step one: Identify all the information we have

    • V₁= 180 mL

    • P₁= 0.678 atm

    • T₁= 45 C + 273.15 = 318.15 K

    • V₂= 79 mL

    • P₂=

    • T₂=​ 273 K

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Manipulate the original equation and plug in your values.

​Step 1

​Step 2

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​Step 3

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​Final EQ

plug in your values.

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​Final EQ

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• V₁= 180 mL

• P₁= 0.678 atm

• T₁= 45 C + 273.15 = 318.15 K

• V₂= 79 mL

• P₂=

• T₂=​ 273 K

Fill in the Blank

A gas that has a volume of 28 liters, a temperature of 45 ⁰C, and an unknown pressure has its volume increased to 34 liters and its temperature decreased to 35 ⁰C. If I measure the pressure after the change to be 2.0 atm, what was the original pressure of the gas? (tenths place __._) unit atm

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Solving for T₂

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Manipulate the original equation and plug in your values.

​Step 1

​Step 2

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​Step 3

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​Final EQ

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​Step 4

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​Step 5

Manipulate the original equation and plug in your values.

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​Final EQ

Open Ended

The initial temperature of a 1.00 L sample of argon is 20.0° C. The pressure is decreased from 720.0 mm Hg to 360.0 mm Hg, and the volume increases to 2.14 liters. What was the change in temperature of the argon?