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level: 7.1 -

Questions and Answers List

level questions: 7.1 -

QuestionAnswer
Define oxidationgain of oxygen by an element Loss of electrons
Define reductionloss of oxygen Gain of electrons
When oxidation and Reduction always take place together what is this reaction called?Redox reaction
What are 2 other ways of finding out whether or not a substance has been oxidised or reduced during a chemical reaction- Electron transfer - Change in oxidation number
What are half equations?divide reactions into separate equations, one showing oxidation and the other showing reduction
In a redow reaction what must be equal?Number of electrons lost and gained
What is an oxidation number, and what does that show us?Oxidation number is a number given to each atom or ion in a compound that shows us its degree of oxidation
What does a higher positive oxidation number mean?That an atom or ion is more oxidised
What does a higher negative oxidation number mean?That an atom or ion is more reduced
What are the 6 rules to deduce the oxidation number of any atom or ion by oxidaion?1. Oxidation number of uncombined elements is zero 2. In compounds many atoms or ions have fixed oxidation numbers 3.The oxidation number of an element in a monatomic ion is always the same as the charge 4. The sum of the oxidation numbers in a compound is zero 5. Sum of oxidation number in an ion is equal to the charge on the ion 6. Either a compound or an ion, more electronegative elements is given negative oxidation number
In compounds many atoms or ions have fixed oxidation numbers: (5)1. Group 1 elements are always +1 2. Group 2 elements are always +2 3. Fluorine is always -1 4. Hydrogen is +1 (except in metal hydrides is -1) 5. Oxygen is -2
Metals always have a (+ / - ) oxidation numberPositive
Non-metals always have a (+ / - ) oxidation numberNegative
In compounds containing 2 different non-metals, the sign of the ox.no. depends on whatthe electronegativity of each atom
What are compound ions?Ions with 2 or more different atoms
What does the oxidation number refer to?a single atom or ion in a compound
Oxidation is an (ic / dc) in oxidation numberIncrease
Reduction is a (ic/dc) in oxidation numberDecrease
What is oxidising agent (oxidant)?Substance which brings about oxidation by removing electrons from atom or ion.
What does a oxidising agent do, and when this happens. What happens to oxidation number. Give 3 examples of oxidising agents.1. Oxidising agent increases the oxidation number of another atom or ion 2. The oxidation number of the oxidising agent decreases 3. Oxygen, chlorine and potassium manganate(VII).
What is a reducing agent (reductant) ? What happens to oxidation number ? Give 3 examples of reducing agents.A reducing agent decreases the oxidation number of another atom or ion Oxidation number of the reducing agent increases 3. Hydrogen, potassium iodide and reactive metals (aluminium).
Names of ions containing oxygen and one other element end in'-ate'
Names of inorganic acids containing oxygen end in'-ic'
What are the steps in constructing equations using oxidation numbers (4)?1. Identify oxidation number changes 2. Balance oxidation number changes 3. Balance charges 4. Balance atoms