O Level Chemistry: Element, Compounds & Mixtures

Q) Explain why air is considered a mixture & not a compound or element?

Do show us your reasoning as much as possible.

Sean

PS: Check “Comments” below for Suggested Answers.

Related Articles:

2 Responses to O Level Chemistry: Element, Compounds & Mixtures
  1. Jennifer
    March 14, 2008 | 6:00 pm

    Hello. I would like to have a take at this question

    Air is a mixture because its constituents, nitrogen, oxygen, carbon dioxide, noble gases, water vapour are not chemically combined. This is because, at different places, the composition of air varies.

    Air can be separated by physical methods like fractional distillation whereby air is first cooled and compressed. Then, nitrogen having a lower boiling point of -196 degree Celsius gets distilled over first, followed by argon, oxygen. This explains why the boiling and melting point of air varies according to its composition.

    There is also no chemical formulae for Air unlike compounds.

    The reason why air is not an element is because an element is a pure substance that has only one type of atom whereas air has few types of atoms.

    Reply

  2. sean
    March 15, 2008 | 8:09 am

    Hi Jennifer.

    Good attempt at this question on Elements, Compounds & Mixtures.
    That is a good answer.

    Below will be my suggested answer to differentiate between Compounds & Mixture.
    It is based on SPEC.
    S – Separation
    P – Properties
    E – Energy Changes
    C – Composition

    Ans:

    Air is considered as a Mixture of different gases, and not as Elements or Compounds.

    S – Different fractions of gases in the air can be separated by physical means, e.g. Fractional Distillation

    P – Each of the gases has their own properties. E.g., Oxygen still support combustion and relights a glowing splint, Carbon Dioxide will continue to turn limewater cloudy.

    E – No Heat/Light are involved when the different gases come together to form air.

    C – Ratio of each fraction of gases can vary from place to place. E.g., at places where burning occurs, % of carbon dioxide is higher and % of oxygen is lower, etc

    Hope this helps.
    Sean

    Reply

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://www.simplechemconcepts.com/chemistry-question-element-compounds-mixtures/trackback/