[Forumz]

Hello,

Part of our unit was based on Classifying matter.  
Thee following could either be classified as a Substance, Element, Compound, or Mixture.

Air     Gasoline     a Nickle Coin     Sea Water     Stone     Paper     Fresh Water     Wood     Asprin     Water     Iron     Glass     Steam     Steel     Mercury     Ice    Nickel     a Flame  

 
I have the answers, but only because they have been supplied.  Is there any hints, tips and/or tricks to help classify these in the correct fashion?  Thanks in advance.

[mike]

An element you can pretty well pick if it also appears on the periodic table (ie it is made up of only one type of atom) for example iron would be an element. Iron appears on the periodic table and a piece of iron is only made up of iron atoms.

A compound is generally made of two or more things that have been combined to form a new thing. For example water is a compound because it is made up of two hydrogen atoms (element) and an oxygen atom (element). You can see that the atoms that make up water are elements on their own, but when they are joined together they make a new compound (H2O).

A mixture is made up of two or more parts that are mixed together but are not combining to form one new compound. For example salt water could be considered a mixture of two compounds, salt and water. The are mixed to form a salt water but you know that in that mixture are still separate salt molecules and water molecules (ie the salt molecule has not reacted with water it is just mixed with it).

I am not completely sure of what they expect you to classify as a substance as I would call all of these things substances (maybe someone else can have a go at substance)?

[arnyk]

One thing that stands out is the flame.  It is certainly a heat element, but really just energy.  "Substance" is a bit ambiguous if you ask me.

[Forumz]

SUBSTANCE = SOLUTION!!!!!!

My Apologies!!!!

[mike]

OK, so in that case sea water would more likely be a solution  

I guess a solution would be considered any mixture that was completely homogenous.

[Forumz]

Thanks everyone for the Replies!  They've all helped me alot

The only one i'm confused about now is a nickel coin, how's it a solution?  Wouldn't it be a compound?  Again, i'm sure i'm missing a simple concept here.  Thanks to all again



(Sorry about the typo earlier )

[mike]

Well this depends on some definitions. I am Australian so we don't have nickel coins but I googled them and found out they are American coins comprising of a Copper-Nickel alloy.

Now copper and nickel are both elements.

If you definition of a solution is two or more elements or compounds combined homogenously then the nickel would be a solution. I tend to think that solutions are liquids though so this is a little confusing.

You can say that the coin is not an element, or a compound, it could be a mixture but as the constituent substances are homogenously mixed it is not a true mixture I suppose. Although an alloy could be the mixture of two metals. This seems to be a question with no set answer, it all depends on the definition that was given to you in the first place.

[xiankai]

a solution need not be liquid in liquids like oxygen in air, although most solutions commonly are. hence an alloy qualifies as a solution i think.