redox reactions

Question 1

what is a redox reaction?

Answer 1

since an oxidation and reduction reaction always take place together, this combined process is called a redox reaction

Question 2

in a redox reaction, what happens to oxygen?

Answer 2

oxidation=gains oxygen
reduction=loses oxygen

Question 3

in a redox reaction, what happens to hydrogen?

Answer 3

oxidation=loses hydrogen
reduction=gains hydrogen

Question 4

in a redox reaction, what happens to the electrons?

Answer 4

oxidation=loses electron(s)
reduction=gains electron(s)

Question 5

in a redox reaction, what happens to the oxidation states?

Answer 5

oxidation=increase
reduction=decrease

Question 6

what is an oxidising agent?

Answer 6

a substance that causes another substance to be oxidised. however, it reduces itself

Question 7

what is a reducing agent?

Answer 7

a substance that causes another substance to be reduced. however, it oxidises itself

Question 8

what is an oxidation state?

Answer 8

an oxidation state refers to the charge an atom of an element would have if it existed as an ion in a compound (even if its covalently bonded).

Question 9

what is the oxidation state of free elements? and what are some examples of free elements?

Answer 9

0
eg. Mg Cl2

Question 10

what is the oxidation state of simple ions? and what are some examples of simple ions?

Answer 10

the oxidation state of a simple ion is the same as the charge of the ion
eg. Na+=+1
O2-=-2

Question 11

sum of oxidation states?

Answer 11

the sum of oxidation states of the atoms or ions in a compound add up to zero

Question 12

what do the roman numerals in the name of a compound indicate?

Answer 12

it indicates the oxidation state of the transition element
eg. copper(II) sulfate= copper=+2

Question 13

what is the charge for group 1 elements?

Answer 13

always +1

Question 14

what is the charge for group II elements?

Answer 14

always +2

Question 15

what is the charge for flourine?

Answer 15

always -1

Question 16

what is the charge for oxygen?

Answer 16

usually -2
exceptions: H2O2 and OF2

Question 17

what is the charge for hydrogen?

Answer 17

usually +1
exceptions: BH3 and metal hydrides: NaH, AlH3

Question 18

what happens to a substance when its oxidation state increases?

Answer 18

the substance is oxidised

Question 19

what happens to a substance when its oxidation state decreases?

Answer 19

the substance is reduced.

Question 20

what can be determined through oxidation state changes?

Answer 20

oxidation state changes is the most accurate way to determine whether a substance is oxidised or reduced. hence, the chance of it being tested is the highest

Question 21

what do we compare when identifying oxidation state changes?

Answer 21

we compare the same elements on both sides of the equation

Question 22

how to test for presence of oxidising agent?

Answer 22

use potassium iodide
if present, colourless potassium iodide changes to brown

Question 23

how to test for presence of reducing agent?

Answer 23

use acidified potassium manganate
if reducing agent is present, purple potassium manganate turns colourless.