Loading please wait

The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Inhaled and Exhaled Air

In this worksheet, students will explain the main differences between inhaled and exhaled air.

'Inhaled and Exhaled Air' worksheet

Key stage:  KS 3

Curriculum topic:   Biology: Structure and Function of Living Organisms

Curriculum subtopic:   Gas Exchange Systems (Breathing)

Difficulty level:  

Worksheet Overview

Breathing

 

Breathing

 

Everyone knows that we breathe in oxygen and breathe out carbon dioxide. But that's not technically true. The truth is we breathe in air and breathe out air... so what's the difference?

 

Inhaled Air

 

So, we need oxygen to live, but do you know how much of the air is made up of oxygen? 80%? 75%? ....it actually only makes up about 21% of the air.  

So what else is in there?

The air that is all around us is made up of mostly nitrogen, about 78% nitrogen in fact. So what about the other 1%? ...The other 1% is made up of 0.04% carbon dioxide, some water vapour and other gases such as argon, helium and neon.  

 

Pie chart of gases of the air

 

Exhaled Air

 

The reason we breathe is to get oxygen into our bodies to allow for respiration, so you would think that the air we breathe out would have a lot less oxygen right? Well, there is less oxygen in exhaled air but probably a bit more than you would expect. Exhaled air actually contains around 16% oxygen which means we only use about 5% of the oxygen available!

The percentage of nitrogen stays at nearly 78% (as we do not have any use for nitrogen) but the main difference is the increase in carbon dioxide. The carbon dioxide in exhaled air is more-or-less 4% and the percentage of water vapour is also higher than in inhaled air.  

 

 Pie chart of gases of the air

 

Experiment Time

 

There is a very simple experiment that we can do to prove that exhaled air contains more carbon dioxide than inhaled air.

Carbon dioxide will turn colourless limewater milky/cloudy.  

 

Blowing into limewater

 

The CO2 percentage in inhaled air is so small that it doesn't have an effect on the limewater, however bubble some exhaled air through it and it will turn milky/cloudy. 

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started
laptop

Try an activity or get started for free

  • educational
  • bettfutures
  • cxa
  • pta
  • era2016
  • BDA award
  • Explore LearningTuition Partner
  • tacm