Chemistry Assignment
Chemistry Assignment

Question 1:
Silver salts are known as phytochemicals. Identify what this term means and discuss an industrial application for the use of silver salts.
Silver salts are type of chemicals in which silver react with halides/halogens to form light sensitive chemical compounds. For example, silver nitrate, silver chloride, silver bromide etc.
Silver nitrate:
Properties of Silver Nitrate:
Molecular Formula- AgNO3
Molar Mass- 169.87 g mol-1
Melting Point- 212 °C, 485 K, 414 °F
Boiling Point- 444 °C, 717 K, 831 °F (decomp.)
Solubility in Water- Very soluble
Solubility- Soluble in ethanol and acetone

Ag + 2 HNO3 → AgNO3 + NO2 + H2O
Silver nitrate is prominently used in the field of medicine. It is used in the manufacturing of eye drops from 1881. It is used to prevent any hereditary eye infection that might be passed from their mothers. Experiments have proven that this is very effective in eliminating gonococcal bacteria in eye.

Question 2:
Identify the equation for the electrolysis of water and identify an industrial application for this reaction.

It is a chemical process in which a substance is broken down into its simple components through the use of electricity.
The equation for electrolysis is:
2H2O (l) --> 2H2 (g) + O2 (g)
Electrolysis is used for electroplating of metals. It is used to put a thin layer of metal on another metal to prevent it from corrosion. The metal that is used for coating is deposited around cation. When electricity is passed through the solution, the positive cations move towards the negative cathode and gain electrons to form a thin layer of coating around the cathode. This is also used to improve the appearance of certain metals.

Question 3:
Construct and discuss the limitations of models of ionic lattices, covalent molecules and covalent and metallic lattices
Ionic lattice:
These are the attraction between opposite charges. The strength of the bond between them is very strong and requires lots of energy to break them which makes the particles to move around. This makes it a good conductor (when liquid and solution form), hard and brittle and have high melting and boiling points.

Covalent lattice:
This is a type of bonding in which some elements and some covalent compounds form a lattice of atoms in a 3-dimension crystal structure. These bonds are formed when a pair of electrons is being shared which makes it very strong. This requires a lot of energy to be broken so the particles in this lattice move around.

Covalent molecular:
These are covalent bond between molecules and have intra-molecular (inside) and intermolecular (between) bonds. These are very weak and hold the molecules in place but are easily broken by heat energy which causes the molecules to move around.

Metallic bond:
These are the bonds between metal ions which are surrounded a sea of delocalised electrons. This readily conducts electricity as electrons flow around the metal ions. These are good conductors of heat and electricity.

Limitations of these models: 1) Ionic and covalent bonds are not stick-like structures. They are held by an invisible force of attraction. 2) The structure of atoms and ions are not in the shape of a ball. 3) The proportion of these models are wrong. 4) The use of colors to identify different parts are unreal.

Question 4:
Process and present information from secondary sources on the range of compounds found in coal, petroleum or natural gas and on the location of deposits of the selected fossil fuel in Australia.
Natural gas, petroleum and coal are known as hydrocarbons. These hydrocarbons are composed of hydrogen, carbon and some impurities. Natural gas contains hydrocarbons that remain at 20°C. Hydrocarbons that have higher carbon molecules are liquid. The main component in natural gas is methane (usually 70%-90%). If it contains more than 95% of methane and less than 5% of heavier hydrocarbons (ethane, propane and butane), it