Explain why elements and compounds are pure substances

N2 - Element; Pure substance O2 - Element; Pure substance N2O - Compound; Pure Substance Air - Homogeneous; Solution

Elements and compounds are substances because we know exactly what is in them. Elements are only one kind of atom and have a symbol. Compounds have a formula telling us exactly how many of what kind of atom make up that compound

Solutions, homogeneous mixtures, not only contain 2 compounds, but we do not know how much of each. We can make salt water with one grain of salt in a cup of water or a drop of water in a cup of salt. Mixtures do not have a formula because they can be any concentration.

We first assume that this gas is an ideal gas where it follows the ideal gas equation. the said equation is expressed as: pv = nrt. from this equation, we can predict the changes in the pressure, volume and temperature. if the volume and the temperature of this gas is doubled, then the pressure still stays the same.