Chemistry Help

[Firestar]

I am going to be taking Honors Chemistry next year, and currently, I have summer homework. The one thing I need help with now is that I have absolutely no idea what the difference between heterogeneous and homogeneous -erm, mixtures- are. Help, please?

Thanks in advance.

 

[miles01110]

http://en.wikipedia.org/wiki/Mixture

 

[mobilehaathi]

not to be, erm, an a**, but have you tried a dictionary?

 

[Firestar]

not to be, erm, an a**, but have you tried a dictionary?

I have the definitions in the science book, I just don't understand how to apply them.

 

[mobilehaathi]

I have the definitions in the science book, I just don't understand how to apply them.

what don't you understand about the definitions?

 

[imaketouchtheme]

I'll give an example.

A heterogenous mixture is like putting non-soluble rocks in a cup of water.

A homogenous mixture is like putting sugar in a up of water.

Basically, you can't separate a homogenous mixture without applying a chemical reaction.

 

[mobilehaathi]

I'll give an example.

A heterogenous mixture is like putting non-soluble rocks in a cup of water.

A homogenous mixture is like dissolving sugar in a up of water.

Basically, you can't separate a homogenous mixture without applying a chemical reaction.

So, what don't you understand? I would also assert that you can separate a homogeneous mixture without a chemical reaction.

Edit: If I may correct myself, dissolving sugar in water is more accurately a solution.

 

[Firestar]

what don't you understand about the definitions?

I don't understand the part about one being "uniform" and one not.

I'll give an example.

A heterogenous mixture is like putting non-soluble rocks in a cup of water.

A homogenous mixture is like putting sugar in a up of water.

Basically, you can't separate a homogenous mixture without applying a chemical reaction.

Alright. That makes a lot of sense. Thanks. (I might have further questions that I might use this thread for, as my Chemistry teacher is apparently not very prompt at answering her email.)

So, what don't you understand? I would also assert that you can separate a homogeneous mixture without a chemical reaction.

When dissolving the sugar, to seperate the sugar from the water, you would need to distill it, which would be a chemical reaction, I think.

 

[Tomorrow]

I don't understand the part about one being "uniform" and one not.

A heterogeneous mixture is not the same throughout. Think of fresh milk (straight from the cow's udder, that is) - the cream will rise to the top. It's not the same as the milk at the bottom of the container.

A homogeneous mixture is the same throughout. Fresh milk is homogenized - that is, made the same throughout - by spraying it, milk fat and all, through a very fine nozzle. In this case, the cream will no longer rise to the top.

Another example is putting sugar into your iced tea; the sugar tends to congregate at the bottom of the glass, rather than completely dissolving. This type of mixture is heterogeneous. Using Sweet N Low in your tea (which completely dissolves) makes a homogeneous mixture; each part of the glass of tea is as sweet as any other.

 

[mobilehaathi]

I don't understand the part about one being "uniform" and one not.

Alright. That makes a lot of sense. Thanks. (I might have further questions that I might use this thread for, as my Chemistry teacher is apparently not very prompt at answering her email.)


When dissolving the sugar, to seperate the sugar from the water, you would need to distill it, which would be a chemical reaction, I think.

So solutions are a subset of homogeneous mixtures. Mixtures that aren't solutions can be mechanically separated (i.e. reach in and grab the rocks, use a centrifuge to separate homogenized water and oil). Solutions, I believe, require some sort of reaction in order to separate. It has been a long time since I thought about chemistry, so this might not be precisely correct, however it should be close enough for your purposes.

 

[Firestar]

Another example is putting sugar into your iced tea; the sugar tends to congregate at the bottom of the glass, rather than completely dissolving. This type of mixture is heterogeneous. Using Sweet N Low in your tea (which completely dissolves) makes a homogeneous mixture; each part of the glass of tea is as sweet as any other.

This made more sense to me. So basically, if something is evenly distributed throughout, that makes it homogeneous, while the opposite for heterogeneous?

 

[Tomorrow]

This made more sense to me. So basically, if something is evenly distributed throughout, that makes it homogeneous, while the opposite for heterogeneous?

Correct. Think of the Greek prefixes "homo" (meaning "same") and "hetero" (meaning "different").

 

[Firestar]

Correct. Think of the Greek prefixes "homo" (meaning "same") and "hetero" (meaning "different").

Alright. Very many thanks.