chem paper 1 definitions

Question 1

molecular formula

Answer 1

the number of atoms of each element in a molecule

Question 2

empirical formula

Answer 2

the simplist whole number ratio of atoms of each element in a compound

Question 3

relative molecular mass

Answer 3

the mass of a molecules relative to 1/12th the mass of carbon 12

Question 4

CuSO4-H2O

Answer 4

-H2O stands for the water of crystallisation

Question 5

ionic bonding

Answer 5

the electrostatic attraction between positive and negatively charged ions in an ionic compound

Question 6

solubility of ionic compounds

Answer 6

ionic compounds dissolve in polar solvents such as water.

the ionic lattice is broken down
the water molecules attract and surround the ions

Question 7

factors which effect the solubility of ionic compounds

Answer 7

greater the electrostatic attraction between ions, greater the solubility

Question 8

covalent bond

Answer 8

the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 9

metalic bonding

Answer 9

the strong electrostatic attraction between postive cations and delocalised electrons

Question 10

qualitative analysis test order and why?

Answer 10

carbonate test, sulphate test then halide test

if not in this order you can get false results

barium ions can react with carbonate forming barium carbonate, white insoluble precipitate

halide test you can for AgCO3 or AgSO4
which are both white precipitates and insoluble

Question 11

silver halide soluble in what type of NH3

Answer 11

AgCl = dilute NH3
AgBr = conc NH3
AgI = not soluble

Question 12

testing for NH4+

Answer 12

add hydroxide ions, ammonia gas produced. warm up mixture and test gas produced with a moist pH indictor paper. paper will turn blue is positve

Question 13

factors which effect rate constant

Answer 13

• increasing temperature

Question 14

calcutlating rate from half life

Answer 14

K=ln2/halflife

Question 15

partial pressure of (A) = ?

Answer 15

mole fraction of A x total pressure

Question 16

Kc and Kp units respectively

Answer 16

moldm^3 and Kpa

Question 17

what does the magnitude of an equilibrium constant indicate of a chemical equilibrium ?

Answer 17

k= 1 equilibrium half way
k=100 equilibrium way in favour of products
k=10^-2 equilibrium was in favour of products

Question 18

when does K change?

Answer 18

only changes if temperature changes

Question 19

if forward reaction is exothermic, and temperature increases. what happens to Kp

Answer 19

Kp decreases as the system is no longer in equilibrium .

equilibrium shifts to the left so reactions partial pressure increases and products partial pressure decreases

Question 20

how do you calculate pH of a strong acid ?

HA——> H+ (aq) + A- (aq)

Answer 20

[HA] = [H+] as HA completely dissocates

Question 21

Ka is used for …..

Answer 21

weak acid dissociation

Question 22

the two Ka approximations

Answer 22

• [H+] equilibrium = [A-] equilibrium

[HA] start = [HA] equilibrium as the dissociation is small

Question 23

what to use to find pH of strong bases

Answer 23

Kw equation

Kw= [H+][OH-]