SMU - Random Physical and Inorganic Questions

Question 1

what is the difference between the terms thermodynamics and chemical kinetcs

Answer 1

chemical kinetics concers the speed of a reaction, linking to collision theory.
thermodynamics concers if a reaction can occur spontaneously or not, entropy being a majour part.

Question 2

what are valence electrons

Answer 2

they are the electrons that take part in the chemical bond,

Question 3

what are lewis structures

Answer 3

they are just pictoral representations that hsow valence electrsons as dots around an atom, and bonds as lines

Question 4

what is the difference between amphoteric and amphiprotic

Answer 4

amphoteric compounds can act as both acids and bases, but amphiportic componuds can donate or accept protons making them both bronstead lowry acids and bases

Question 5

give an example of an amphiprotic molecule

Answer 5

HCO3^-
H2O
H2PO4^-
HSO4^- (bisulfate ion)

Question 6

test for hydrogen gas

Answer 6

H2 burns in the presence of oxygen, to form water vapour very quickly, releeasing energy.

• the enrgy released expands water vapour which rushes out of the test tube forming a squeaky pop sound.

Question 6

test for CO2

Answer 6

it reacts with lime water to form CaCO3, turning into a milky white precipitate
CO2 + Ca(OH)2 -> CaCO3 + H2O

Question 7

what are 2 feuturres that can be used to detect presence of CO2

Answer 7

obvs - tunrs lime water milky
also - extinguishes fire -
cos CO2 is denser than O2, when sprayed over a fire, it sinks under the O2. essentailly displaces the O2 that is feeding the fire.

Question 8

Metal + acid ->

Answer 8

salt + H2

Question 9

Metal Carbonate + acid ->

Answer 9

Salt + CO2 + H20

Question 10

Metal + base ->

Answer 10

salt + H2

Question 11

Acid + metal carbonate
(lemon jiuce + baking soda)

Answer 11

Salt + CO2 H2O

Question 12

Is water acidic, basic or amphoteric

Answer 12

amphoteric, can act as a base and acid

Question 13

what is the autoionisation of water

Answer 13

when hydrogen ions are spontaneously generated in pure water by the dissociation of a small percentage of water molecules.

H20 <=> H+ + OH-

The H+ go on to bind with neighbouring water molecules to form H3O+ molecules.

Question 14

how does the strength of the acid effect where the equilibrium shifts
(if the acid is dissociating on it’s own).

Answer 14

if the acid that is dissociating is stronger, the equilibrium shifts the forward direction.

Question 15

define the terms
alkali and alkaline
and establish a relationship betweeen the two.

Answer 15

solutions or substances that have a pH greater than 7, meaning they are basic and can neutralise acids = thy are referred to as alkaline.

alkali - refers to a type of base that is soluble in water and forms OH- ions in solution.

all alkalis are alkaline but not all alklaline substances are alkalis.
eg - NH3 is alkaline but not alkali cos it doesn’t form OH- ions in water.

Question 16

State the reactivity series

Answer 16

potassium
sodium
calcium
magnesium
aluminium
carbon
zinc
iron
tin
lead
hydrogen
copper
silver
gold
platinum.

Question 17

can group 1a elements conduct electricity and heat

Answer 17

yes ofc - dummy :)

Question 18

what are group IA elements called

Answer 18

they are called alkali metals, cos their oxides are soluble in water
(group 1)

Question 19

what are group IIa elements called

Answer 19

alkaline earth metals. (group 2)

Question 20

what are the elements in -
VIIA
VIIIA

Answer 20

the halogens (group 7)

Question 21

what elements are found in the IB group and what is another name for them

Answer 21

copper, silver and gold
- aka the coinage metals.
the group 11 elements.

Question 22

what elements are the metalloids.

Answer 22

(semiconductors)
Boron
silicon
germanium
arsenic
antimony
tellurium
pollonium
astatine

(along the metal and non-metal seperation line)

Question 23

what columns make up the transition metals

Answer 23

coloumns IIIB, IVB, VB, VIB, VIIB, ViIIB,

each column has its own number,
but the last 3 columns from Fe-Co-Ni are all under the VIIIB group.

Question 24

what columns come under the term ‘main group elements’

Answer 24

columns with A, so from IA to VIIIA

Question 25

how doe intermolecular forces affect vapour pressure.

Answer 25

those with storger intermolecule forces like hydrogen bonding, will have lower vapour pressure, becuase fewer molecules will have enough kinetic energy to escape at a given temperature.

Question 26

atomic radius trend

Answer 26

down the group - increases - extra shell added.
across the period - decreases - increased attraction for increaased no. of electrons in same energy level.

Question 27

ionic radius trend

Answer 27

same as atomic radius
down the group = increases
across a period = decreases

Question 28

cation radii compared to parent atomic radii

Answer 28

cations have a smaller radius compared to the parent atom.
cos the no of protons is higher than the number of electrons, so there is stronger attraction.

Question 29

anion radii compared to parent atomic radii

Answer 29

anions have larger radii than their parent atoms, cos extra electrons added, casues greater repulsion between valence electrons.

Question 30

reducive properties of the halide ions - trend and why

Answer 30

I- > Br- > Cl- > F-
cos as you go down the group, extra electron shells are being added, so the outer electron on the ions can easily be lost, they get oxidised quickly and ability to reduce something else occurs quickly.

Question 31

what are the products when Iron (II) Sulfate (FeSO4) reacts with potassium dichromate (K2Cr2O7)
and what redox is happening here

Answer 31

Cr2(SO4)3 , Fe2(SO4)3 , K2SO4
chromiun sulfate, ferric sulfate and potassium sulfate

chromium gets reduced = +6 -> +3
iron gets oxidised = +2 -> +4

Question 32

foam - what is is made up of.

Answer 32

gas (like bubbles of air) are dispersed in a liquid medium (the soap or detergent).

Question 33

positive and negative catalyst

Answer 33

positive = increases ROR
negative = decreases ROR

Question 34

• What is henry’s law.
• what does decreasing the volume do?
• what conditions are necessary for it to occur

Answer 34

the solubility of a gas it directly proportional to the partial pressure of that gas.
- occurs at constant temperature.

decreasing the volume of the solution = increases the pressure of gas particles in the solution = increasing solubility.

temp constant, occurs with a dilute acid at low pressures, and there should be no chemical interaction between the gas and solvent.

Question 35

state the relationship between the degree of dissociation and (α) concentration of electrolytes

Answer 35

only with weak eletrolytes and of dilute concentrations

as the concentration decreases, the degree of dissociation increases.
as conc increases = α decreases.

Question 36

state ostwalds law

Answer 36

at infinite dilution, the degree of dissociation (α) of a weak electrolyte is directly proportional to the square root of the concentration.

C increases = α decreases
C decreases = α increases

α = √(K/c)

(k is the dissociation constant)