An introduction to geology
An introduction to geology

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

An introduction to geology

2.6 Soda cans from bauxite

A typical bauxite ore is 50% Al2O3. Remember, Al has an atomic mass of 27, O is 16, so bauxite is 26.5% Al. Using this information, see if you can complete the activity below. Again, don't worry if you have some difficulty with this – it takes some practice.

Activity 2.1 Extracting Al from bauxite

Timing: Allow about 10 minutes

How much bauxite do you need to make a 15 g soda can?


134 g


56.7 g


30.1 g

The correct answer is b.


The answer is 56.7 g bauxite:

50% bauxite is 50% Al2O3.

50 postfix times percent cap a times l sub two times cap o sub three times prefix multiplication of 54 divided by 102 postfix times postfix times equals percent cap a times l

equation left hand side 15 times g times cap a times l divided by 26 times eight divided by 17 postfix division 100 equals right hand side 56 postfix times two divided by three times g postfix times cap b times a times u times x times i times t times e postfix times

So it’s around four times more efficient to use bauxite as a source of Al than a typical igneous rock like granite – and that’s because the geological process, in this case weathering, does a lot of the work for us.


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371