Separating Mixtures

Question 1

Define soluble, insoluble, and saturated

Answer 1

Soluble: describes that a substance can dissolve in a specific solvent

Insoluble: describes a substance that cannot dissolve in a particular solvent

Saturated: describes the state in which a solvent cannot dissolve any more of a solute at a specific temperature

Question 1

Define solvent, solute, and solution

Answer 1

Solute: the substance that can dissolve (usually a solid)

Solvent: the liquid that the solute dissolves in

Solution: the mixture of a dissolved solute and solvent

Question 2

Explain filtration

Answer 2

• Used when separating insoluble solids from a liquid
  1) Pour the solution into a filter funnel
  2) The liquid is able to go through the tiny holes in the filtration paper and goes through the filter funnel and into the conical flask
  3) You are now left with the filtrate in the flask and the residue in the funnel

Question 3

Explain decantation

Answer 3

• Separation technique effective on liquids with different densities or when an insoluble solid is present in a liquid
  1) Pour the substance into the separatory funnel. The denser substance should always be at the bottom.
  2) Open the stop cork to allow the substance at the bottom to flow through.
  3) Close the stop cork as soon as all of the denser substance has been drained out of the separatory funnel into the conical flask.

Question 4

Explain distillation

Answer 4

• Used when separating liquids and gases using their boiling points
• From liquid to gas, increase the heat
• From gas to liqud, decrease the heat

1) Heat the solution in the distillation flask to the appropriate temperature
2) The desired substance evaporates and as the vapour goes through the condenser, the constantly flowing cold water condenses the vapour
3) The liqudi in its purest form ends up in the beaker

Question 5

Explain fractional distillation

Answer 5

• Used for the same purposes as distillation but when the substances’ boiling points are close to one another
  1) Mixture is boiled
  2) The substance goes through the fractionating tower
  3) As the vapour reaches each tray within the tower, a specific substance condenses as the condensation point is right for that specific substance

Question 6

Explain chromatography

Answer 6

• Used to separate the components of a solute (e.g., dye)
  1) Fill the beaker with the solvent.
  2) Hang the chromatography paper with mixture implemented on the base line (made of pencil)
  3) Let the solvent travel to the through the chromatography paper
  4) The solvent will carry the mixture and dissolve them. Each component has a specific Rf value in that solvent and will therefore travel a certain distance, separating the mixture.

Question 7

Define element, compound, and mixture

Answer 7

Element: a pure substance that is made up of a single type of atom have the same number of protons in their nucleus

Compound: consists of molecules that are identical to one another and are made up of two or more chemically-bonded elements

Mixture: the physical combination a group of two or more substances without any chemical bonding

Question 8

Explain the basic structure of an atom

Answer 8

Nucleus:
- Made up of protons and neutrons
- Has a tiny volume yet huge mass compared to the rest of the nucleus

Protons:
- Has a relative mass of 1 amu (atomic mass unit)
- Has a relative charge of +1, therefore it is positively charged
- Atoms of the same element have the same number of protons
- Number of protons are shown on the periodic table as the atomic number

Neutrons:
- Has a relative mass of 1 amu
- Has a relative charge of 0, so it is neutrally charged
- Number of neutrons varies in atoms of the same element and determines what isotope that atoms is

Electrons:
- Atomic mass of electrons is extremely small in comparison to protons and neutrons, practically 0
- Number of electrons = number of protons
- The number of electrons being greater or less than the number of protons will create a charged atom called an ion
- Ions with more electrons than protons will create a negative charge but less electrons than protons will create a positive charge

Energy level/shell:
Energy levels are fixed distances from the nucleus where electrons can be found

Question 9

Explain crystalisation

Answer 9

• Used on solutions where the solvent’s boiling point is lower than the solute’s

1) Heat the solution in the evaporating basin at the right temperature
2) The solvent evaporates
3) You are now left with the solute
4) Let it cool down, allowing it to form crystals

Question 10

Define stationary and mobile phase

Answer 10

Stationary phase: when mixture is staying still and is more attracted to the paper

Mobile phase: when mixture is moving and is attracted to the solvent and moving along it

Question 11

How to calculate Rf value?

Answer 11

distance travelled by solute/distance travelled by solvent (solvent front)

Question 12

How to calculate average relative atomic mass?

Answer 12

((abundance of A x mass of A) + (abundance of B x mass of B))/100