C2.1 Purity And Seperating Mixtures

Question 1

What is an alloy?

Answer 1

A mixture of a metal and at least one other element

Alloys are often created to enhance certain properties, such as strength or corrosion resistance.

Question 2

What does a balanced chemical equation represent?

Answer 2

A model for a reaction showing formulae and number of units for all substances involved

It ensures that the law of conservation of mass is followed.

Question 3

Define boiling point.

Answer 3

The temperature at which a substance changes from the liquid state to the gas state

Boiling point varies depending on atmospheric pressure.

Question 4

What is a carrier gas?

Answer 4

An unreactive or inert gas used as the mobile phase in gas chromatography

Common carrier gases include helium and nitrogen.

Question 5

What is a chemical formula?

Answer 5

A description of a compound or an element that uses symbols to represent the atoms present

Numbers indicate if more than one atom of an element is present.

Question 6

What is a chromatogram?

Answer 6

The pattern produced when separating a mixture using chromatography

It visually represents the different components of the mixture.

Question 7

Define chromatography.

Answer 7

A separation method that relies on the distribution of a substance between a mobile phase and a stationary phase

It is widely used for analyzing complex mixtures.

Question 8

What does it mean to condense?

Answer 8

To change from the gas state to the liquid state

This process often occurs when gas cools down.

Question 9

What is a condenser?

Answer 9

Apparatus that can cool and condense a substance

Commonly used in distillation processes.

Question 10

What is crystallisation?

Answer 10

The process by which crystals are formed during evaporation of a solvent from a solution

It is often used to purify solid compounds.

Question 11

Define dissolve.

Answer 11

The process in which a solute and solvent mix completely to form a solution

This typically occurs at the molecular level.

Question 12

What is an empirical formula?

Answer 12

Formula showing the simplest whole-number ratio of the atoms of each element in a compound

It differs from the molecular formula, which shows the actual number of atoms.

Question 13

What does it mean to evaporate?

Answer 13

When a substance turns from the liquid state to the gas state at a temperature below the boiling point

This process can occur at any temperature.

Question 14

Define filtrate.

Answer 14

Liquid that passes through the filter during filtrations

It contains the dissolved substances left after insoluble materials are removed.

Question 15

What is filtration?

Answer 15

The process by which insoluble substances are separated from soluble substances using a filter

This method is commonly used in laboratories.

Question 16

What is a fraction in chemistry?

Answer 16

Substance separated during fractional distillation

Each fraction contains components with similar boiling points.

Question 17

Define fractional distillation.

Answer 17

Method for separating a mixture of liquids with different boiling points into different fractions

It is widely used in the petrochemical industry.

Question 18

What is a fractionating column?

Answer 18

A piece of apparatus used to improve the separation of solvents during fractional distillation

It increases the efficiency of the distillation process.

Question 19

What is gas chromatography?

Answer 19

A type of chromatography that uses silica or alumina packed into a metal tube as the stationary phase, and an unreactive or inert carrier gas as the mobile phase

It is used for analyzing volatile substances.

Question 20

What is an impure substance?

Answer 20

Material consisting of two or more different elements and/or compounds.

Question 21

Define insoluble.

Answer 21

Describes a substance that will not dissolve.

Question 22

What is the melting point?

Answer 22

The temperature at which a substance changes from the solid state to the liquid state.

Question 23

What is a mixture?

Answer 23

Material consisting of two or more different substances, not chemically joined together.

Question 24

What is the mobile phase in chromatography?

Answer 24

A substance in the liquid or gas state that moves during chromatography.

Question 25

What is paper chromatography?

Answer 25

Separation method that uses paper as the stationary phase and a solvent in the liquid state as the mobile phase.

Question 26

What is the periodic table?

Answer 26

A table in which the elements are arranged in rows (periods) and columns (groups), in order of increasing atomic number.

Question 27

What does the term phase refer to in chemistry?

Answer 27

A substance in the solid, liquid, or gas state.

Question 28

Define a pure substance.

Answer 28

Consisting of just one element or compound.

Question 29

What is purity?

Answer 29

A measure of how pure a substance is.

Question 30

What is relative atomic mass?

Answer 30

The mean mass of an atom of an element compared to 1/12 the mass of a 12C atom, defined as 12 exactly.

Question 31

What does the symbol Ar stand for?

Answer 31

Relative atomic mass.

Question 32

What is relative formula mass?

Answer 32

Mr, the mean mass of an atom of an element compared to 1/12 the mass of a 12C atom, defined as 12 exactly.

Question 33

How is relative formula mass calculated?

Answer 33

By adding together the relative atomic masses for the atoms in the formula of a substance.

Question 34

What is relative molecular mass?

Answer 34

Relative formula mass applied to a molecular substance.

Question 35

What is residue in filtration?

Answer 35

Insoluble material left behind during filtration.

Question 36

What does Rf value represent in chromatography?

Answer 36

Relative distance travelled by a substance during chromatography.

Question 37

Fill in the blank: A saturated solution is a solution containing the maximum mass of solute at a given _______.

Answer 37

temperature.

Question 38

What is simple distillation?

Answer 38

Method to separate a solvent from a solution.

Question 39

Define solubility.

Answer 39

A measure of how much solute can dissolve in a given solvent at a certain temperature.

Question 40

What is a soluble substance?

Answer 40

A substance that will dissolve in a given solvent ## Footnote This definition applies to various contexts in chemistry, particularly in solutions.

Question 41

Define solute.

Answer 41

Substance that dissolves in a solvent ## Footnote The solute is typically present in a lesser amount compared to the solvent.

Question 42

What is a solution?

Answer 42

A mixture formed when one substance dissolves in another ## Footnote Solutions can be homogeneous mixtures of solids, liquids, or gases.

Question 43

What is a solvent?

Answer 43

A substance that can dissolve a solute to form a solution ## Footnote Solvents are usually present in a greater amount than solutes in a solution.

Question 44

What does stationary phase mean in chromatography?

Answer 44

A substance in the solid or liquid state that does not move during chromatography ## Footnote The stationary phase is essential for the separation of components in a mixture.

Question 45

What is thin-layer chromatography?

Answer 45

A type of chromatography that uses silica or alumina spread on a plate as the stationary phase, and a solvent in the liquid state as the mobile phase ## Footnote This method is widely used for separating non-volatile mixtures.

Question 46

What is vapour?

Answer 46

A substance in its gas state and below its boiling point ## Footnote Vapour can exist in equilibrium with its liquid or solid phase.