Below is information about John Dalton and his law. These pictures, captions, and formulas might help when looking at our project.


John Dalton was born on September 5, 1766 in Cumberland, England. His family was poor, but he was able to get an education and was brilliant in mathematics. He discovered the law of partial pressures in the early eighteen hundreds, and lectured about them in 1803. In 1808, his book called A New System of Chemical Philosophy was published, and he changed the scientific world forever.

In our project, we tested Dalton's Law by experimenting with different mixtures of air. The regular air we breathe is made up of approximately eighty percent nitrogen and twenty percent oxygen. We used two other forms of air called nitrox. In the nitrox, the partial pressures of the nitrogen and the oxygen are different from the partial pressures in regular air. In one mixture the partial pressure of the nitrogen is sixty percent and the partial pressure of the oxygen is forty percent. In the other mixture the partial pressure of the nitrogen and oxygen is fifty percent.

Dalton's Law states that the total pressure of a gas is equal to the sum of the partial pressures of that gas. For example, if there is a mixture made up of three different gasses, the total pressure should be equal to the partial pressures of all three different gasses added together. In our experiment, this means that the partial pressures of the nitrogen and oxygen in a specific mixture of air should equal the total pressure of that mixture when added together. In an equation, this looks like:

P(total)= P(1) + P(2) + P(3)...P(n)

P(1)=Partial pressure of first gas

P(2)=Partial pressure of second gas

P(3)=Partial pressure of third gas

n=number of gasses

We wanted to prove Dalton's Law. We believed that when we removed the oxygen from the different mixtures of air, the remaining pressure would be equal to the original partial pressure of the nitrogen. See the remainder of this site to see how we tested this.

 Great Links: click on the address to go to website

For Nitrox and Nitrogen Narcosis:

For John Dalton:


Background Information

 Lab Report

Method & Materials 


Results and Conclusion

Analytic Essay





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