1.5.1

Ideal Gas Equation

Test yourself

The Ideal Gas Equation

Most gases obey a simple law known as the ideal gas equation. This describes the relationship between the pressure, volume and temperature of a gas.

Illustrative background for The ideal gas equationIllustrative background for The ideal gas equation ?? "content

The ideal gas equation

  • The ideal gas equation is:
  • Pressure × volume = number of moles × gas constant × temperature
  • PV = nRT
  • This equation can be used to calculate any variable in the equation, as long as you know the other three variables.
    • P, V, n, and T are the variables.
    • R is a constant - its value is always 0.08206.
Illustrative background for Importance of unitsIllustrative background for Importance of units ?? "content

Importance of units

  • When using the ideal gas law, it is important to make sure you are using only SI units:
  • Pressure must be in atmospheres (atm).
  • Volume must be in liters (L).
  • Temperature must be in Kelvin (K).
  • These units are the scientific standard - they are all related and allow for easily understood numbers.
  • Using different units will give you the wrong answer!
Illustrative background for An exampleIllustrative background for An example ?? "content

An example

  • The pressure of 1 mole of a gas is 1 atm at a temperature of 298 K. What is its volume?
    • PV = nRT
    • V = nRT ÷ p
    • V = 1 × 0.08206 × 298 K ÷ 1 atm
    • V = 24.8 L

The Kelvin Scale

The Kelvin scale is a temperature scale that is commonly used in science. For the SAT Chemistry Subject Test you need to be able to convert °C to Kelvin.

Illustrative background for The Kelvin scale Illustrative background for The Kelvin scale  ?? "content

The Kelvin scale

  • The Kelvin scale is an absolute temperature scale defined to have 0 K at the lowest possible temperature, called absolute zero.
Illustrative background for Absolute zeroIllustrative background for Absolute zero ?? "content

Absolute zero

  • Absolute zero (0 K) is the lowest possible temperature.
  • At absolute zero, there is no temperature.
    • This means that there is no kinetic energy or vibration of molecules.
Illustrative background for Converting from degrees to KelvinIllustrative background for Converting from degrees to Kelvin ?? "content

Converting from degrees to Kelvin

  • To find degrees from Kelvin, just add 273.
    • E.g. 0oC = 273 K.
    • E.g. Water boils at 373 K.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium