Discovering chemistry
Discovering chemistry

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

Discovering chemistry

3 Gunpowder – the explosive reaction of charcoal, sulfur and potassium nitrate

An explosive is a material that releases large quantities of hot gas extremely rapidly, and very violently.

Indeed, the following quote is attributed to Roger Bacon (Figure 1), a Franciscan monk who introduced gunpowder (also known as blackpowder) to Europe in the 13th century:

‘By the flash and combustion of fires, and by the horror of sounds, wonders can be wrought, and at any distance that we wish, so that a man can hardly protect himself or endure it.’

Described image
Figure 1 Roger Bacon

Gunpowder consists of sulfur and charcoal (fuels), mixed with potassium nitrate (an oxidiser – a type of chemical which a fuel requires in order to burn).

The basic mixture was, in fact, originally discovered by eighth century Chinese alchemists. However, Bacon experimented with the relative proportions and undertook a detailed scholarly investigation into the explosive. As a consequence he incurred the wrath of the Church, and suffered long term imprisonment for his efforts. However he did manage to preserve his recipe for blackpowder in the form of an anagram (Figure 2).

Described image
Figure 2 Bacon's anagram for the composition of gunpowder

In fact on line two, you can make out the word ‘saltpetre’, the old fashioned name for potassium nitrate.

  • A simplified (unbalanced) equation for the deflagration (a self-propagating burning surface reaction) of gunpowder is shown below – re-write this in balanced form.

    KNO3 + S + C = K2S + CO2 + N2
    Equation label: (5.9)
  • 2KNO3 + S + 3C = K2S + 3CO2 + N2
    Equation label: (5.10)
DC_1

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