Mathematics is also involve in chemistry. There are many application inside chemistry, for example mole calculation, pH calculation, half life of radioactive element, etc.

We will show some example about those application on next page.

Half life of radioactive element

Half life of radioactive element means after the radioactive element have placed for a long time (for example, 5000

years!). You may ask why there is a radioactive decay in the radioactive element, this is because when the radioactive

element is taken out from its ore, it emit particles, particles and rays. This make the some of the protons and neutrons also electrons, this action make the strength of the radioactive element weaker, also the radioactive element

may change to another element such as lead.

he simple concept of half life can be represent by following mathematics formula:

A=(1/2)n

Where ‘A’ is the radioactive of the element and ‘n’ is the number of half life decay which had happen to the element.

The above is a application using radiation decay to calculate the age of a fossil. Next slide shows a example.

Example:

A fossil contains only 1/32 carbon-14 when it was living, how many years did the fossil have been die?

As we know the half- life of carbon -14 is 5730 years.

(1/2)n= 1/32

n=5

So the years that the fossil have been die is:

=(5)(5730)

=28650years.

From above mathematics enable us to estimate the year of fossil, since it is impossible visit the fossil died in many thousand years ago!!!!

Mole concept in chemistry

As we know atoms, ions and molecules are hard to count, we can’t count them one by one.

So mathematics can enable us to count them indirectly by weighting the substance.

By definition one mole of substance in equal to 6.02 x 1023 of units of its particles.

(left) chemical substance using mole to represent its concentration.

Calculation of pH in chemistry

The equation in pH calculation is:

pH = - log10[H+(aq)]

For example:

H2O -> H+(aq) + OH-

(aq)

in pure water only 1/10000000 of hydrogen and oxygen molecule can ionize to ion, so the pH of pure water is:

pH = - log10(1/10000000)

pH= - log10(10-7)

pH= -(-7)

=7

So mathematics calculation can enable us to measure pH without pH paper.