Chem Tys

Question 1

Melting point down grp I vs grp VII

Answer 1

I: decr MP
VII: incr MP

Question 2

Reactivity down grp I vs VII

Answer 2

I: incr reactivity
VII: decr reactivity

Question 3

Ethene use vs ethyl ethanoate use

Answer 3

Ethene: to make polymers for packaging
Ethyl ethanoate: ink solvent

Question 4

Evidence that a org compound group is a homologous series 4

Answer 4

• same general formula
• same functional group
• successive members differ by -CH2-
• gradation in physical properties (if shown)

Question 5

Products of FULL combustion of a organic compound

Answer 5

~ + O2 -> CO2 + H2O

Question 6

Explain why Haber process mixes N2 and H2 in 1:3 ratio

Answer 6

Using avogadros law: 1 mol N2 reacts w 3 mol H2, hence 1:3

Question 7

Effect of pressure of FINAL amt of ammonia made in Haber

Answer 7

Unreacted gases recycled, final amt same regardless of pressure

Question 8

Conc aq solution products

Answer 8

The products are of the aq solution cause they are both in high conc

Question 9

Oxygen gas at positive electrode equation ionic

Answer 9

4OH- —> O2 + 2H2O + 4e-

Question 10

When adding random reagents and asking for observations

Answer 10

• see if the resulting salts form ppt (insol)
• see if there’s metal to displace
• acids? Are there metals?

Question 11

When metal added to carboxylic acid OBSERVATIONS

Answer 11

Effervescence observed
Rate of reaction slower than inorganic acid

Question 12

Argon is used in…

Answer 12

Manufacture of steel!
Iron too ofc

Question 13

Paraffin is used as

Answer 13

Aircraft fuel

Question 14

Why isotopes have identical chemical properties

Answer 14

Same number of VALENCE electrons

Question 15

Definition Relative Atomic Mass

Answer 15

Ratio of the average mass of an atom of an element to 1/12th of the mass of an atom of carbon-12

Question 16

Definition disproportionating reaction

Answer 16

The same element is simultaneously oxidised and reduced in the same chemical reaction

Question 17

Disadvantage of non biodegradable shit

Answer 17

Incr waste sent to landfills (takes up space) or incinerators

Question 18

Speed of reaction

Answer 18

Incr gradient of graph = incr speed of reaction

Question 19

Fuel cells (Chem of reaction)

Answer 19

Reactants are CONTINUOUSLY SUPPLIED to produce electricity, HYDROGEN usually used as its RENEWABLE AND POLLUTION FREE. however, it’s EXPENSIVE, FLAMMABLE AND LIGHT (^space req to store)

Question 20

Bacicity of acids def

Answer 20

The max number of H+ ions produced by a molecule of an acid

Monobasic = 1H+
Dibasic = 2H+

Question 21

Element that shows both metallic and non metallic character

Answer 21

Hydrogen

Question 22

Element used for galvanising

Answer 22

Zinc (galvanise= coat iron or steel w prot layer of zinc)

Question 23

Properties of transition elements

Answer 23

• form coloured compounds
• variable oxidation states in their compounds
• they and their compounds are good catalysts

Question 24

Colour of silver IODIDE

Answer 24

yellow

Question 25

Photoystensis equation

Answer 25

6CO2 + 6H2O -> C6H12O6 (aq) + 6O2

Question 26

Respiration equation

Answer 26

C6H12O6 (aq) + 6O2 -> 6CO2 + 6H2O

Question 27

How respiration and photosynthesis maintain carbon cycle

Answer 27

Amt of C by both is same

Question 28

Process used to manufacture alkenes

Answer 28

Catalytic cracking

Question 29

Why are alkane fractions cracked further

Answer 29

Less useful longer chain alkanes eg diesel and LO -> shorter chain alkanes eg petrol w higher demand

Question 30

Bromination

Answer 30

AQUEOUS bromine used

Question 31

Vegetable oil -> margarine how

Answer 31

Add H2 gas to VO, temp of 200C and nickel catalyst (hydrogenation)

Question 32

Calcium added to salt solutions, fizzing

Answer 32

V reactive, forms calcium hydroxide + H2 gas

Question 33

More soluble chromatography

Answer 33

Higher up More soluble = Rf closer to 1

Question 34

Mole calc dm3 triangle

Answer 34

Dm3 Mol | 24

Question 35

Rate of decomp of metal carbonates

Answer 35

More reactive = carbonate more stable = need higher temp to decomp

Question 36

Blast furnace

Question 37

When asked about Mr of gases and diffusion

Answer 37

HIGHER mr = LOWER ro.d = water level higher/lower

Question 38

Which is giant molecular

Answer 38

MOLECULAR not ionic If it looks like smt u don’t see in covalent DONT pick it

Question 39

Insoluble salt prep

Answer 39

You’ll probably need to acidify it first Just remember: IT DOESNT NEED TO BE CRYSTALLISED

Question 40

You’re gonna need quantitative analysis

Answer 40

roger roger

Question 41

In redo eqns assign each reactant to its product carefully to see if it’s reduced or not

Answer 41

Eg ~ + H2O2 + H+ —> O2 + H2O H2O2 is OXIDISED to O2 not reduced to H2O H2O2 is the only source of O, H+ can gain O

Question 42

Get your highlighter out girl your eyes are not to be trusted

Answer 42

Noted 👍

Question 43

In the alkene reaction with the UV light

Answer 43

Only ONE H atom is replaced by a C or F at one time What’s it called btw

Question 44

When something (eg a hydrocarbon) is hydrolysed,

Answer 44

it adds WATER to it. H2O. NOT THE CATALYST???

Question 45

Why is there ammonia in QA result?

Answer 45

There’s gotta be nitrate somewhere 👈😎👈 NH3/4 y’all

Question 46

Ammonium salt + ____ -> ammonia gas

Answer 46

Alkali !!! Like limewater

Question 47

Why are additional things added in some processes

Answer 47

Impurity reduces melting point -> less energy required

Question 48

Why is silicon dioxide solid while sulfur dioxide gas

Answer 48

SiO2 = covalent bonds Stronger than SO2 = intermolecular forces of attraction

Question 49

Flue gas desulfurisation first main product

Answer 49

Calcium sulFITE + oxygen -> calcium sulfate

Question 50

Molecules present in mixture after bromination of methane

Answer 50

- hydrogen bromide - dibromomethane NO HYDROGEN

Question 51

What excess reactant can be used to make potassium lactate from lactic acid

Answer 51

- potassium hydroxide / carbonate Remember it’s an ACID. Standard reactions apply

Question 52

When metal occurs naturally as an element

Answer 52

Not very reactive (cannot be extracted by electrolysis)

Question 53

Redox reactions: is it redox? 🤨🤷‍♂️

Answer 53

If it’s only one reactant it probably isn’t. It might be a disproportioantion reaction!

Question 54

Which statements about cracking of hydrocarbons is correct? 1. Involves breaking down hydrocarbon molecules 2. One of the products is always unsaturated 3. Cracking is essential cause of demand for smaller fractions

Answer 54

ALL OF THE ABOVE

Question 55

Given % by mass of each element in X, what other info is needed to determine molecular formula?

Answer 55

Mr of the elements and Mr of X

Question 56

Cropper oxide reduced to copper via heating, dry hydrogen gas pumped into the tube until tube is cold. Why?

Answer 56

Prevents copper from reacting with oxygen in air

Question 57

What can be used with sublimation

Answer 57

Ammonium chloride Dry ice Iodine

Question 58

Impurities will

Answer 58

Raise bp Lower mp

Question 59

Diff gases, same moles, volume?

Answer 59

Same (abocardos law, 6 x 10^23)

Question 60

Change in mass of cathode and anode when reactive electrode

Answer 60

Anode mass decr Cathode mass incr No net gain or loss of ions in the solution, no colour change

Question 61

Electroplating

Answer 61

Object to be plated is the cathode Plating metal is the anode

Question 62

Simple cell

Answer 62

More reactive metal oxidation (neg electrode) Less reactive reduced (pos electrode) Higher diff in reactivity = higher voltage (If electrolyte is dilute sulfuric acid, H+ ions to H2 gas at lower reactivity)

Question 63

Enthalpy change calculation

Answer 63

PRODUCTS - REACTANTS

Question 64

Acidic soil?

Answer 64

Add quicklime (CaO) or slaked lime (Ca(OH)2)