Chemistry

Question 1

Molar mass

Answer 1

the mass in grams of one mole of that substance.

Question 2

solute

Answer 2

substance that is dissolved in the solution

Question 3

solvent

Answer 3

substance in which another substance is dissolved, forming a solution.

Question 4

Concentration

Answer 4

the number of moles of solute per unit volume of solution.

Question 5

standard solution

Answer 5

solution of known concentration.

Question 6

Electronegativity

Answer 6

measure of the tendency of an atom to attract a bonding pair of electrons.

Question 7

covalent bond

Answer 7

the sharing of at least one pair of electrons by two atoms.

Question 8

non-polar covalent (pure covalent)

Answer 8

an equal sharing of electrons.

Question 9

polar covalent bond

Answer 9

unequal sharing of electrons leading to a dipole forming.

Question 10

ionic bond

Answer 10

the transfer of electrons and subsequent electrostatic attraction.

Question 11

Metallic bonding

Answer 11

between a positive kernel and a sea of delocalised electrons.

Question 12

Intermolecular force

Answer 12

a weak force of attraction between molecules or between atoms of noble gases.

Question 13

Intramolecular bond

Answer 13

the bond occurring between atoms within molecules.

Question 14

The heat of reaction (AH)

Answer 14

the net change of chemical potential energy of the system.

Question 15

Exothermic reactions

Answer 15

reactions which transfer potential energy into thermal energy.

Question 16

Endothermic reactions

Answer 16

reactions which transfer thermal energy into potential energy.

Question 17

Activation energy

Answer 17

the minimum energy required to start a chemical reaction.

Question 18

catalyst

Answer 18

a substance that increases the rate of the reaction but remains unchanged at the end of the reaction.

Question 19

Dipole-dipole forces

Answer 19

Forces between two polar molecules

Question 20

Induced dipole forces or London forces

Answer 20

Forces between non-polar molecules

Question 21

Hydrogen bonding

Answer 21

Forces between molecules in which hydrogen is covalently bonded to nitrogen, oxygen or fluorine,

Question 22

activated complex

Answer 22

temporary transition state between the reactants and the products.

Question 23

positive catalyst

Answer 23

a substance that increases the rate of a chemical reaction without itself undergoing a permanent change.