3.9 Modern Purification Methods

1. What is the best method to separate sand from water?

Filtration

Gas chromatography

Paper chromatography

Layer separation

Filtration would be the best method because you want to get an insoluble solid out of a liquid.

Explanation

Filtration would be the best method because you want to get an insoluble solid out of a liquid.

We discussed earlier some common methods of purification. In this screencast, we will discuss more methods of purification including the ones we will be using in school along with ones that are a little bit more high tech and more expensive.

Earlier we discussed the process of filtration... see moreand of crystallization. We also talked about distillation for liquids with different boiling points. Now we are adding some more advanced forms of distillation including vacuum distillation (used for substances with high boiling points), and spinning ban distillation (for liquids with similar boiling points).

There are also some more advanced types of chromatography. There is paper chromatography, used mostly in high schools, thin layer chromatography (for small amounts of solids), gas chromatography (for separating gases of course), and high performance liquid chromatography (used for very complex mixtures of liquids and/or solids. )

A new type of purification is layer separation. This is used for liquids that cannot dissolve in each other and form layers (like oil and water. ) One liquid can be drained out the bottom while keeping the other in the container. see less

2. When you have a mixture of many different liquids and solids and you don't know what any of them are, it would be easiest to use thin layer chromatography to separate all of the parts.

True

False

It would be much easier to us HPLC, high performance liquid chromatography. This machine will tell you everything that is in your mixture. Thin layer chromatography is for small amounts of solids. Here you have liquids too and you have a lot of everything.

Explanation

3. The boiling point of propyl alcohol is 97.5 degrees celcius while water's is 100 degrees celcius. These two are relatively close, so to separate a mixture of them I will use

Vacuum Distillation

Layer separation

Spinning band distillation

Thin layer chromatography

Spinning band distillation would be the best option because this method can help separate two liquids with close boiling points.

Explanation

Spinning band distillation would be the best option because this method can help separate two liquids with close boiling points.

4. Crystallization is best used for ___________ __________.

When you crystallize something, you are reforming a solid. Think about the process of rock candy to help you remember this one. First you dissolve sugar in water, then you crystallize it on a stick.

Explanation

When you crystallize something, you are reforming a solid. Think about the process of rock candy to help you remember this one. First you dissolve sugar in water, then you crystallize it on a stick.

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5. Check all that apply: High Performance Liquid Chromatography is used to separate

Complex mixtures of solids

Complex mixtures of liquids

Complex mixtures of gases

Complex mixtures of cheerios

HPLC is used to separate complex mixtures of liquids and solids that are too complex for other means of purification. Complex mixtures of gases should be separated using gas chromatography. Cheerios can be separated by hand...

Explanation

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