chap 6 key terms

Question 1

aqeuous solution

Answer 1

Aqueous solution- When chemical species has been dissolved in water, the resulting solution is said to be aqueous. This can be shown by writing ‘(aq)’ after the name or symbol of the chemical.

Question 2

chromatogram

Answer 2

Chromatogram- The output of a chromatography procedure. In TLC and paper chromatography, it is the pattern of bands or spots formed on a plate or on the paper. In HPLC, it I the graph produced.

Question 3

chromatography

Answer 3

Chromatography- A technique for separating the components of a mixture. The components are carried by a mobile phase over the absorbent surface of the stationary phase.

Question 4

components

Answer 4

Components- the chemicals in a mixture. The components can be separated by chromatography.

Question 5

desorption

Answer 5

Desorption- The breaking of the attraction between a substance and the surface to which the substance is absorbed.

Question 6

dispersion forces

Answer 6

Dispersion forces- The force of attraction between molecules due to temporary dipoles induced in the molecules. The temporary dipoles are the result of random fluctuations in the electron density.

Question 7

dissociation

Answer 7

Dissociation- A process in which molecules or ionic compounds separate or split into smaller particles such as atoms or ions. Examples of dissociation reactions include the solution of NaCl solid in water, forming Na+(aq) and Cl-(aq) ions, and the reaction of HCl gas with water, forming H+(aq) and Cl-(aq).

Question 8

dissolution

Answer 8

Dissolution- The process of dissolving a solute in a solvent to form a solution.

Question 9

homogenous

Answer 9

Homogeneous- Uniform. The components of a homogenous substance, e.g. a solution is homogeneous because the solute and the solvent cannot be distinguished from each other.

Question 10

hydrated

Answer 10

Hydrated- An ion surrounded by water molecules. Hydrated ions can be found in aqueous solutions or crystalline solids.

Question 11

hydrogen bonds

Answer 11

Hydrogen bonds- A type of intermolecular, dipole-dipole force where a hydrogen atoms is covalently bonded to a highly electronegative atom such as oxygen, nitrogen or fluorine. Due to the disparity of the electronegativity values between the atoms involved, the hydrogen develops a partial positive charge and bonds to lone pairs of electrons on neighbouring atoms of oxygen, nitrogen or fluorine.

Question 12

immiscible

Answer 12

Immiscible- Two liquids are immiscible if they cannot be mixed without separating from each other.

Question 13

ion-dipole attractions

Answer 13

Ion-dipole attractions- The attraction that forms between dissociated ions and polar water molecules when an ionic solid dissolves in water.

Question 14

ionisation

Answer 14

Ionisation- (i) the removal of one or more electrons from an atom or ion; (ii) the reaction of a molecular substance with a solvent to form ions in solution.

Question 15

miscible

Answer 15

Miscible- Liquids that can be mixed ion any ration to form a homogeneous solution.

Question 16

mobile phase

Answer 16

Mobile phase- The phase that moves over the stationary phase in a chromatographic separation.

Question 17

non-polar

Answer 17

Non-polar- Bonds or molecules that do not have a permanent dipole. They have an even distribution of charge.

Question 18

origin

Answer 18

Origin- The point at which a small spot of a mixture is placed so that is can be separated by paper or thin-layer chromatography.

Question 19

paper chromatography

Answer 19

Paper chromatography- An analytical technique for separating and identifying mixtures that uses paper as the stationary phase.

Question 20

polar

Answer 20

Polar- Bonds or molecules with a permanent dipole. They have an uneven distribution of charge.

Question 21

purity

Answer 21

Purity- In chemical terms, a material is pure if it only contains a single substance, without any other substances present.

Question 22

qualitative analysis

Answer 22

Qualitative analysis- An analysis to determine the identity of the chemical(s) present in a substance.

Question 23

quantitative analysis

Answer 23

Quantitative analysis- An analysis to determine the concentration of the chemicals present in a mixture.

Question 24

retardation factor

Answer 24

Retardation factor (Rf)- The ratio of the distance a component has moved from the origin to the distance the solvent has oved from the origin.

Question 25

solute

Answer 25

a substance that dissolves in a solvent

Question 26

solution

Answer 26

Solution- A homogeneous mixture of a solute dissolves in a solvent.

Question 27

solvent

Answer 27

Solvent- A substance, usually a liquid, which is able to dissolve a solute to form a solution. Water is a very good solvent.

Question 28

standards

Answer 28

Standards- Standards are materials with an identity and concentration that are precisely known. A standard can provide a reference that can be used to calibrate analytical instruments or determine unknown concentrations.

Question 29

stationary phase

Answer 29

Stationary phase- A solid, or a solid that is coated in a viscous liquid, used in chromatography. The components of a mixture undergo absorption to this phase as they are carried along by the mobile phase.

Question 30

thin-layer chromatography

Answer 30

Thin-layer Chromatography- An analytical technique for separating and identifying mixtures; it uses a thin layer of fine powder spread on a glass or plastic plate as the stationary phase.