Stupid Question about Hetero/Homogeneous mixtures

In summary, the conversation was about whether salt and sand are heterogeneous or homogeneous mixtures. The expert summarizer explains that salt is a compound and not a mixture, so it cannot be classified as either. However, in the context of a mixture, salt can be considered heterogeneous because it may contain different particles. The expert also provides a general explanation for differentiating between homogeneous and heterogeneous mixtures. The conversation also touches on the composition of solid brass and the concept of solid solutions.
  • #1
Saladsamurai
3,020
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I was just asked "Are salt and sand heterogeneous or homogenous mixtures?" I can see that sand is heterogeneous, but why is salt heterogeous?

Casey
 
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  • #2
i normally think of heterogeneous and homogeneous this way

homogenous: think of it as 2 boys (same gender)

heterogeneous: boy and girl (different genders)

please don't laugh lol

so salt is heterogeneous cause u see different particles (color wise w.e.)

but salt, its all the same white crystals or w.e. so thay makes it heterogeneous

ya this isn't the greatest explanation chemistry wise but it helps me remember!

hope it helped bud :-)
 
  • #3
kenvin100 said:
i normally think of heterogeneous and homogeneous this way

homogenous: think of it as 2 boys (same gender)

heterogeneous: boy and girl (different genders)

please don't laugh lol

so salt is heterogeneous cause u see different particles (color wise w.e.)

but salt, its all the same white crystals or w.e. so thay makes it heterogeneous

ya this isn't the greatest explanation chemistry wise but it helps me remember!

hope it helped bud :-)


I think you mixed up something.. . . I can't make heads or tails of your explanation. Thanks though!
 
  • #4
Salt isn't a mixture, it's a compound.
 
  • #5
Mitchtwitchita said:
Salt isn't a mixture, it's a compound.

Well, the book wants to know if salt is homogeneous or heterogeneous.
 
  • #6
Oh, well then I'd guess heterogeneous because the sodium and chloride ions occupy distinct areas (and thus distinct properties) within the packing structure of a salt crystal.
 
  • #7
Interesting. I think that answers it then. It was a question in my girlfriends text and they said the answer was heterogeneous too. . . but I just couldn't see why and it was driving me nuts! Thanks
 
  • #8
Saladsamurai said:
I was just asked "Are salt and sand heterogeneous or homogenous mixtures?" I can see that sand is heterogeneous, but why is salt heterogeous?

Casey
The question is if sand, or salt is a homogeneous/heterogeneous mixture? About salt, If he intended "grains of salt mixed with air", then it's a heterogeneous mix, but if you consider a single grain it's not a mix at all since it's a pure compound. In general, when you have 2 or more different compounds (and so a mix), the mix is homogeneous if it's formed by a single phase and so is a solution, heterogeneous if two or more phases. Ex: water and oil forms two separate phases (even when one of them is finely emulsionated into the other); water and alcohol instead forms an only phase (homogeneous mix) because they forms a solution.
About sand...i live the answer to you.
 
  • #9
Saladsamurai said:
I was just asked "Are salt and sand heterogeneous or homogenous mixtures?" I can see that sand is heterogeneous, but why is salt heterogeous?

Casey

I would say pure salt is a homogeneous substance. No matter how much of it you have, you have equal amounts of Na and Cl. There are well-defined intensive quantities (density and specific heat, for example) that do not vary depending on where you took a small sample of salt.
 
  • #10
Andy Resnick said:
I would say pure salt is a homogeneous substance. No matter how much of it you have, you have equal amounts of Na and Cl. There are well-defined intensive quantities (density and specific heat, for example) that do not vary depending on where you took a small sample of salt.
It doesn't matter if you have equal amounts of Na and Cl; in other compounds (e.g. water) you don't have but they are still homogeneous (NON mixtures); every pure compound in one only phase is homogeneous.
 
  • #11
lightarrow said:
It doesn't matter if you have equal amounts of Na and Cl; in other compounds (e.g. water) you don't have but they are still homogeneous (NON mixtures); every pure compound in one only phase is homogeneous.

Well, yes.. but that's not what I meant. In any homogeneous compound, regardless of how much you have, you retain the stoichiometric ratio of the components. This is not true for things like sand or concrete.
 
  • #12
Andy Resnick said:
Well, yes.. but that's not what I meant. In any homogeneous compound, regardless of how much you have, you retain the stoichiometric ratio of the components. This is not true for things like sand or concrete.
A piece of solid brass is homogeneous or not, for you?
 
  • #13
That's an interesting question. I would say macroscopically it is homogeneous. I don't know enough about the microscopic structure to say anything else. Steel compounds (cementite, austentite, etc) are heterogeneous on a microscopic scale.
 
  • #14
Andy Resnick said:
That's an interesting question. I would say macroscopically it is homogeneous. I don't know enough about the microscopic structure to say anything else. Steel compounds (cementite, austentite, etc) are heterogeneous on a microscopic scale.
Brass is an example of alloy which is a solid solution (with one phase only if Zn concentration is less than 37%) so it's homogeneous, but it doesn't have a specific composition.
 

1. What is the difference between a heterogenous and homogeneous mixture?

A heterogenous mixture is one in which the components are visibly distinct from one another. This means that you can physically see the different substances within the mixture. On the other hand, a homogeneous mixture is one in which the components are evenly distributed throughout, creating a uniform appearance. In this type of mixture, the different substances are not visibly distinguishable.

2. Can a mixture be both heterogenous and homogeneous?

No, a mixture cannot be both heterogenous and homogeneous. A mixture is either one or the other, depending on the distribution of its components. However, a mixture can contain both heterogenous and homogeneous regions. For example, a mixed fruit salad may have some areas where the fruits are evenly mixed (homogeneous) and other areas where one fruit is more concentrated (heterogeneous).

3. What are some examples of heterogenous mixtures?

Some examples of heterogenous mixtures include concrete, tossed salad, and a mixture of oil and water. These mixtures all have visible differences in their components, making them heterogenous.

4. How are homogenous mixtures different from solutions?

Homogeneous mixtures are often referred to as solutions because they have the same composition throughout. However, not all solutions are homogeneous mixtures. A solution is a type of homogeneous mixture in which one substance is dissolved in another, creating a uniform distribution. Other types of homogeneous mixtures include alloys and air.

5. Can a heterogenous mixture be separated into its individual components?

Yes, heterogenous mixtures can be separated into their individual components through physical methods such as filtration, distillation, or chromatography. These methods take advantage of the physical differences between the components, such as size, solubility, or density, to separate them. On the other hand, homogeneous mixtures cannot be easily separated through physical methods because their components are evenly distributed and not visibly distinct.

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