Elements From the Sea Flashcards
How do you calculate atom economy?
% atom economy = Mr of desired product/ Mr of reactants x 100
Why is a high atom economy desirable?
In industrial chemical processes, little to no waste product is desired to make the process economically viable and to preserve raw materials
Define oxidation and reduction
Oxidation - Loss of electrons
Reduction - Gain of electrons
What is disproportionation?
When a species simultaneously is oxidized and reduced to give two different products.
E.g: 2H2O2 –> 2H2O + O2
What are some rules for calculating oxidation numbers?
Oxidation number of an element is 0, in neutral compounds the sum of oxidation states is 0.
Ox. no. of charged compounds add to total charge.
More electronegative elements have a negative oxidation state, and vice versa
What is the oxidation states of: Group 1 elements Group 2 elements Halogens Oxygen Hydrogen
Group 1: +1 Group 2: +2 Halogens: -1 Oxygen: -2 Hydrogen: +1
What is the oxidation states of:
Hydrogen in metal hydride (HX)
Oxygen with fluorine
Oxygen in peroxides
Hydrogen in metal hydride (HX): -1
Oxygen with fluorine: +2
Oxygen in peroxides: -1
What is an oxidizing agent and a reducing agent?
Oxidising agent - Accepts electrons and is reduced, and oxidises another species
Reducing agent - Donates electrons and is oxidized, reducing another species
Define electrolysis
The decomposition of a molten or aqueous ionic compound (electrolyte) by passing an electric current through it, the solution must contain a cathode (-ve) and an anode (+ve)
What determines the products at the cathode(s) with inert electrodes?
If the metal ions are below hydrogen in the electrochemical series, the metal atoms will be produced at the cathode. If they are above hydrogen, H2 will be produced at the cathode
What forms at the anode(s) in an aqueous electrolyte?
Oxygen is generally formed at the anode, unless chloride ions are present, in which case Cl2 will form at the anode
E.g: 2H2O –> 4e- + 4H+ + O2
2Cl- –> Cl2 + 2e-
Explain how an ionic compound is named
Named first by cation then anion. Oxidation state of cation is stated in Roman numerals, while the net charge of the compound must be zero.
E.g: Iron (II) Sulfate (FeSO4)
List the color and state of each halogen at room temp and pressure
Fluorine - pale yellow gas
Chlorine - pale green gas
Bromine - red/brown liquid
Iodine - dark grey solid, sublimes to a purple vapor
How and why does volatility and boiling point change as you go down group 7?
Volatility decreases while boiling point increases due to increase in electrons and molecule size and greater London forces requiring more energy to break
Why are halogens more soluble in hexane than water?
Halogens and hexane are both non-polar, so are soluble, while water is polar.
