1b Elements, Compounds and Mixtures

Multiple Choice

What is the best model for an element?

Multiple Choice

What kind of matter is represented in the model?

• element

• compound

• mixture of elements

• mixture of compounds

• mixture of elements and compounds

Multiple Choice

What is the best model for a compound?

Multiple Choice

What kind of matter is represented in the model?

• element

• compound

• mixture of elements

• mixture of compounds

• mixture of elements and compounds

Multiple Choice

What is the best model for a mixture of elements?

Multiple Choice

What is the best model for a mixture of compounds?

Multiple Choice

What is the best model for a mixture of elements and compound?

Mixtures can be easily separated by physical means

For example, by sieving, filtering or evaporating

Pure substance melt and boil at fixed temperature.

Drag and Drop

If the melting point of the sample you made is 128-134℃, you can see that it is quite ​

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and it is ​

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because it melts over ​

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.

Drag these tiles and drop them in the correct blank above

impure

mixture

a wide range of temperature

Separation of mixture

fitration

crystallisation

simple distillation

fractional distillation

paper chromatography

Multiple Choice

What is the name of this separation technique?

• distillation

• filtration

• evaporation

• chromatography

Filtration

Filtration is used to separate substances according to the size of their particles.

The substance left in the filter paper is called residue and the liquid that comes through is called filtrate.​

Multiple Choice

During filtration, the solid that is trapped in the filter paper is called ..A.. and the liquid that has passed through the filter paper is called ..B..

• A: residue B: filtrate

• A: residue B: filterate

• A: filtrate B: residue

• A: filterate B: residue

​Separation Flowchart

It is important to represent your flowchart of separation correctly in your answers. Indicating what substances you have and what is being separated out.

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Use diamonds for a separation technique, and rectangles for a substance that is being separated out by that technique, or a substance that is being added.

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E.g. ​Given a mixture of dry salt and salt, outline the procedure to obtain dry sand and dry salt.

Crystallisation

Crystallisation can be used to separate a solute from a solution.

e.g. separating NaCl from a NaCl solution.

Subject | Subject

Some text here about the topic of discussion

Multiple Choice

Which one of the following is the name for separation technique in the picture below

• distillation

• dissolving

• evaporation

• decanting

Multiple Choice

What is evaporation (or crystallisation) usually used for?

• To get clean water from dirty water

• To separate a soluble solid (like salt or minerals) from water

• To separate hydrogen from water

• To separate an insoluble solid (like sand) from water

Multiple Choice

What is the physical property on which fractional distillation depends?

• different boiling points

• different melting points

• different solubilities

• different densities

Distillation​

Distillation uses evaporation (heating) and condensation (cooling) to separate the components of a liquid mixture according to their boiling points.

Subject | Subject

Some text here about the topic of discussion

Multiple Choice

Which one of the following is a disadvantage of evaporation?

• It always requires heat

• It cannot be used for insoluble solids

• All of the solute is recovered

• The solvent (liquid part) is not recovered

Multiple Choice

What is the name of this separation technique?

• Simple distillation

• Fractional distillation

• Boiling

• Evaporation

Fractional distillation

• a method for separating a liquid from a mixture of two or more liquids. 

• the liquids in the mixture have different boiling points

• When the mixture is heated, one liquid evaporates before the other

Multiple Choice

The separation technique shown in the image is called what?

• Chromatography

• Distillation

• Centrifuging

• Decanting

Chromatography​

​Chromatography is used to separate the substances in a mixture based on their solubility.

Subject | Subject

Some text here about the topic of discussion

Draw

Circle the most soluble substance in on the chromatography paper below.

Multiple Choice

Chromatography separates substances according to their...

• Density

• Solubility

• Size

• Weight

Example 1: To find out how many types of dyes are in an unknown sample.

Multiple Choice

Is the blue spot more soluble or less soluble than the yellow spot?

• More soluble

• Less soluble

​Copy this down in Page 16 of Lesson Notes.

Example 1: To find out how many types of dyes are in an unknown sample.

Multiple Choice

There are two spots on the chromatogram. How many components are present in the green dye?

• 1

• 2

• 3

• 4

Multiple Select

Fractional distillation is a method for separating

• a liquid from a mixture of solutions

• a liquid from a mixture of solutes

• a liquid from a mixture of solvents

• a liquid from a mixture of liquids

Retention factor

• how much the compound has moved compared to how much the solvent has moved

• Rf = distance moved by compound ÷ distance moved by the solvent

Multiple Choice

What is the formula for the Rf value?

• Rf value = distance travel of solvent / distance travel of solute or sample

• Rf value = distance travel of solute or sample / distance travel of solvent

• Rf value = distance travel of solid / distance travel of liquid

• Rf value = distance travel of residue / distance travel of solution

Rf = distance travel of solute

distance travel of solvent front

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Rf value formula

Key:

Usually measure to the middle of the ink spot.​

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Multiple Select

Which of the inks are pure?

• Blue ink

• Red ink

• Yellow ink

• Green ink

• Black ink