Trials

Question 1

Colour Range of Universal Indicator

Answer 1

Red - Purple

Question 2

Colour Range of Phenolphthalein

Answer 2

Colourless - Pink; colour change [8.3 - 10]

Question 3

Colour Range of Methyl Orange

Answer 3

Red - Yellow; colour change [3.1 - 4.4]

Question 4

Colour Range of Bromothymol Blue

Answer 4

Yellow - (Green) - Blue; colour change [6.0 - 7.6]

Question 5

Recall the properties of a standard solution

Answer 5

• High purity
• Accurately known chemical composition
• Free of moisture (does not absorb water, which would reduce purity)
• Chemically stable
• High molar weight (variations in mass have reduced effect on moles)

Question 6

In preparation for titration, recall rinsing

Answer 6

Volumetric Flask - Distilled water (water is added eventually to the graduation mark)
Burette - Distilled water + Titrant
Pipette - Solution
Conical Flask - Distilled water

Question 7

Recall equivalence point

Answer 7

The point in titration where the acid and base react in their stoichiometric ratios

Question 8

Recall end point

Answer 8

The point in titration where a permanent colour change begins to be observed

Question 9

Recall aldehyde

Answer 9

An aldehyde [-al] has a carbonyl group bonded to a terminal carbon and a hydrogen atom; CHO

Question 10

Recall ketone

Answer 10

A ketone [-one] has a carbonyl group bonded to carbons

Question 11

Recall carboxylic acid

Answer 11

A carboxylic acid [-oic] has a carboxyl group bonded to a terminal carbon; COOH

Question 12

Recall esters

Answer 12

Esters are formed in acid [concentrationed sulfuric acid] catalysed condensation reactions called esterification (reactants: alkanol + alkanoic acid; product: ester + water)

Alkyl alkanoate

Carbonyl group bonded to the alkanoate

Reversible reaction; reflux surrounded by a condenser.
Hydrogen or hydroxide ions as catalyst

Question 13

Recall amine

Answer 13

An amine [-amine] has a nitrogen atom bonded to carbon and hydrogen atoms

Question 14

Recall amide

Answer 14

An amide [-amide] has a carbonyl group bonded to a nitrogen atom, which is bonded to hydrogen or alkyl groups

Question 15

Order the homologous groups in increasing boiling points

Answer 15

1. Hydrocarbons
2. Halogenated hydrocarbons
3. Amines
4. Esters, ketones, aldehydes
5. Alcohols
6. Carbonxylic acids
7. Amides

Question 16

Stater Markovnikov’s Rule

Answer 16

The proton (H) is attached to the carbon atom with greater number of adjacent hydrogen atoms.

Question 17

Which addition reaction(s) of alkenes requires a catalyst

Answer 17

Hydrogenation of alkene [metal catalyst Pt or Pd/C]

Hydration of alkene [weak acid catalyst (stong acids, e.g. HCl will react)]; forms an alcohol

Question 18

Combustion of hydrocarbons

Answer 18

In general, the combustion of hydrocarbons produces water vapour and carbon dioxide

Question 19

Substitution reaction of alkanes

Answer 19

Under UV as a source of energy; not catalyst:
Alkane + Halogen –> Halogenated Alkane

Preference to displace tertiary and secondary hydrogens

Question 20

Recall the bromine water test

Answer 20

The bromine water test is a test to differentiate between saturated and unsaturated hydrocarbons

Under conditions without UV light, an alkane cannot undergo a substitution reaction with bromine water but an addition reaction can occur

Decolourises from orange to colourless

Question 21

Explain why alcohols become more non-polar as the size increases

Answer 21

Alcohols consist of a non-polar and a polar region, with the hydroxide causing the polar region. As the alcohol increases in size, the non-polar region dominates the polar hydroxide

Thus as the size of the alcohol increases, it becomes less soluble in water

Question 22

Given a halogenated hydrocarbon, how can an alcohol be formed?

Answer 22

The halogenated hydrocarbon can undergo a substitution reaction in a solution of hydroxide ions or water as the hydroxide ions will displace the halogen

Question 23

Recall the chemical process of fermentation

Answer 23

Fermentation is an anaerobic reaction [without oxygen]

Carbohydrate [Glucose] –> Alcohol [Ethanol] + Carbon Dioxide

Conditions:
- Yeast
- Acidic environment

Question 24

True or False. Oxidation of ketones is arduous

Answer 24

True.

Question 25

Identify the acidity of amines. Elaborate why

Answer 25

Amines are bases. The nitrogen atom’s electron lone pair allows amines to accept protons [Bronsted-Lowry base] to form a positively charged conjugate acid

Question 26

Recall the dehydration [elimination] of alkanol

Answer 26

The dehydration of alkanol requires a dehydrating agent [hot conc sulfuric acid] and forms alkene and water

Question 27

Recall the oxidation of alcohol

Answer 27

Primary Alcohols oxidise to form alkanal, in turn, carboxylic acid Secondary Alcohols oxidise to form ketones Tertiary Alcohols do not oxidise

Question 28

Recall oxidising agents

Answer 28

ACIDIFIED purple Potassium Permanganate ion [MnO4-] is reduced to the colourless Manganese ion [MN2+] ACIDIFED orange Sodium Dichromate ion [Cr2O7 2-] is reduced to the green Chromium(III) ions, [Cr3+]

Question 29

Improving efficiency of transformers

Answer 29

- Soft iron core - Soak in oils - Laminate core with layers of insulating material - Increase cross-sectional area of wire

Question 30

James Clerk Maxwell's contributions

Answer 30

- United the fields of electricity and magnetism - Applied pre-existing scientific laws: a changing magnetic field induces an electric field and a changing electric field induces a magnetic field - Proposed electromagnetic waves: Self-propagating Perpendicular oscillating magnetic field and electric field Speed of 1/root(εo) --> predicted light was an electromagnetic wave as it was approximate to experimental evidence Predicted the existence of an electromagnetic spectrum

Question 31

Special Relativity experimental evidence

Answer 31

Rossi-Hall --> mu-mesons Greater quantity of mu-mesons than predicted by its half-life. Length contraction [mu-meson] + Time dilation [stationary observer] Hafele-Keating experiment Atomic clocks flown to the East and West; Earth rotation eastly

Question 32

Cathode ray experiments

Answer 32

Crookes' paddlewheel Maltese cross Electric field Magnetic field

Question 33

De Broglie’s Matter Wave Hypothesis

Answer 33

de Broglie proposed that matter had wave properties, applying the principles to the atom -- electrons orbit the atom as standing waves By letting electrons behave as standing waves, it supports Bohr's 1st Postulate as electrons no longer emit radiation As standing wave, wavelength is an integer multiple of the circumference [interference]; ultimately, Bohr's 3rd Postulate

Question 34

Experimental Evidence for Matter Wave Duality

Answer 34

Davisson-Germer experiment - Oxidised nickel lattice crystal structure - Spacing between the individual nickel atoms act as diffraction grating - An electron beam of known voltage was fired at the nickel, reflected and scattered. A rotating detector measured the intensity to have maximas [50 degrees] and minimas; the electron interfered with itself, wave property.

Question 35

Recall common amphiprotic species

Answer 35

- Water - Hydrogen carbonate ion - H2PO4 - HPO4

Question 36

Purpose of reflux

Answer 36

Reflux: - Uses heat to increase reaction rate - Prevents the loss of volatile substances through condensation --> increases yield - Releases pressure, preventing the round bottom flash from shattering

Question 37

Confirmation Tests

Answer 37

Carboxylic acid: - Litmus - Sodium carbonate Alkene: - Bromine water - Acidified potassium permanganate Alcohol: - CaCl2 [remove water] + sodium