Writing chemical equations

Question 1

oxygen is

Answer 1

O2 and not O

Question 2

hydrogen if

Answer 2

H2 and not H

Question 3

nitrogen is

Answer 3

N2 and not N

Question 4

water is

Answer 4

H2O

Question 5

sodium hydroxide is

Answer 5

NaOh

Question 6

nitric acid is

Answer 6

HNO3

Question 7

iron(II) sulfate is

Answer 7

FeSO4

Question 8

iron(III) oxide is

Answer 8

Fe2O3

Question 9

calcium carbonate is

Answer 9

CaCO3

Question 10

when writing equations from worded descriptions, we have to split the formulae into

Answer 10

products and reactants

Question 11

write the equation for: ‘when carbon dioxide reacts with calcium hydroxide, calcium carbonate and water is formed’

Answer 11

CO2 + Ca(OH)2 = CaCO3 + H2O

Question 12

once you have figure out the formulae or the reactants and products of a reactions in an equation, you need to

Answer 12

balance! this is making sure that for each element, the totals are the same on the left and right of the equation

Question 13

coefficients are

Answer 13

the numbers written in front of species when writing an equation

Question 14

when writing coefficients, using

Answer 14

halves is sometimes acceptable, but more so in organic chemistry

Question 15

the state symbols are:

Answer 15

(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous

Question 16

conventional arrows, →, show that reactions are

Answer 16

irreversible

Question 17

the symbol ⇌ shows that reactions are

Answer 17

reversible

Question 18

sometimes conventional arrows are lengthened to make room for writing

Answer 18

reaction conditions or a label to show the stage of the reaction

Question 19

ionic equations show

Answer 19

any atoms and molecules involved, but only the ions that react together, and not spectator ions

Question 20

spectator ions are

Answer 20

the ions in an ionic compound that do not take part in a reaction

Question 21

the three-part process to follow when writing ionic equations is:

Answer 21

1) start with the full equation for the reaction
2) replace the formulae of ionic compounds by their separate ions
3) delete any ions that appear identically on both sides

Question 22

what is the ionic equation for the neutralisation of sodium hydroxide by dilute nitric acid

Answer 22

1) NaOH(aq) + HNO3(aq) → NaNO3(aq) + H2O(l)
2) Na+ + OH- + H+ + NO3- → Na+ + NO3- + H2O
3) OH-(aq) + H+(aq) → H2O(l)

Question 23

ionic half-equation are written for reactions involving

Answer 23

oxidation and reduction