Chemistry 2

Question 1

What are two natural sources of hydrocarbons?

Answer 1

1. Natural gas
2. Crude oil / Petroleum

Question 2

What are the fractions in the fractional distillation of crude oil from top to bottom?

Answer 2

Ryan Paul Never Killed Dennis, Fiona Loves Barry

Refinery Gas
Petrol/Gasoline
Naptha
Kerosene oil (paraffin oil)
Diesel oil
Fuel Oils
Lubricating oils and Waxed
Bitumen (Asphalt)

Question 3

What are the conditions for thermal and catalytic cracking respectively?

Answer 3

Thermal: Temp. up to about 750 degrees Celsius, pressures up to 70 atm

Catalytic: Temp. up to about 500 degrees Celsisus at fairly low pressures in the presence of a catalyst.

Question 4

Name 5 radioisotopes and their uses.

Answer 4

Recall: I See (C) You (U) See (C) Pee (P) AND “Plutonium pacemakers”

(C)arbon-14: Carbon-14 dating
(C)obalt-60: Treat cancer through radiotherapy
(I)odine-131: Treat thyroid cancer
(U)ranium-235: To produce nuclear power
(P)lutonium-238: Heart pacemakers

Question 5

What is an isotope?

Answer 5

An isotope is one of multiple different atoms of a single element that have the same number of protons in their nuclei, but different numbers of neutrons.

Question 6

Define isotopy

Answer 6

Isotopy is the occurrence of atoms of a single element that have the same number of protons in their nuclei, but differing numbers of neutrons.

Question 7

What is a salt. Hence, what is an acid salt?

Answer 7

A salt is a compound formed when some or all of the hydrogen ions in an acid are replaced by metal or ammonium ions.

An acid salt is a compound formed when the hydrogen ions in an acid are only partially replaced by metal or ammonium ions.

Question 8

Quickly construct a table to show the colours of the indicators litmus, methyl orange, screened methyl orange and phenolphthalein in acidic and alkaline solutions respectively.

Answer 8

See textbook pg. 68

Question 9

What are six physical properties of metals?

Answer 9

1. Metals have high melting and boiling points
2. Metals are solid at room temperature (except Hg, mercury)
3. Metals are good conductors of heat and electricity
4. Metals are malleable and ductile (hammered into shape and drawn out into a thin wire)
5. Metals are shiny in appearance
6. Metals have high densities

Question 10

What are the 5 unique properties of water? (Mnemonic)

Answer 10

Mnemonic: Four My Sister’s Vicious Cat

1. Water has a maximum density at (4) degrees Celsius
2. Water has a high (m)elting and boiling point
3. Water is a good (s)olvent
4. Water has a high heat of (v)aporisation
5. Water has a high specific heat (c)apacity

Question 11

Define the term “Pollution”

Answer 11

Pollution is the contamination of the natural environment by the release of unpleasant and harmful substances into the environment.

Question 12

What are four types of water pollutants (Mnemonic)

Answer 12

Mnemonic: ‘NUPH! (like a shortened and badly spelt version of “enough”)

1. (N)itrogen dioxide and sulphur dioxide which cause acid rain when they dissolve in rainwater.
2. (U)ntreated Sewage
3. (P)esticides
4. (H)eavy metal ions

Question 13

What are the four stages of large-scale treatment of water in order (mnemonic)? What occurs in these stages?

Answer 13

Mnemonic: Funny Snakes Find Cheese

1. Flocculation: Certain chemicals such as alum are added so that fine suspended solid particles clump together to form larger particles called floc.
2. Sedimentation: Floc is allowed to settle.
3. Filtration: The clear water above the floc is filtrated to remove any remaining particles. It also removes some microorganisms.
4. Chlorination: Chlorine gas or monochloroamine (NH2Cl) is added to kill any remaining microorganisms.

Question 14

What four methods can be used to remove temporary AND permanent hardness from water (Mnemonic)? Explain the two more involved ones.

Answer 14

Mnemonic: West Indies, Dream Realm

1. Adding (w)ashing soda AKA sodium carbonate
2. Ion-exchange - Water is slowly passed through an ion-exchange column In a water-softening device. The column contains an ion-exchange resin called zeolite (Na2Z). This causes a displacement reaction, causing any calcium or magnesium ions to be absorbed into the zeolite. The sodium ions left do not cause the water to be hard.
3. Distillation
4. Reverse osmosis: Water is forced through a differentially permeable membrane under pressure and dissolved substances remain behind on the pressurized side. This removes calcium or magnesiums ions as well as other ions and most microorganisms.