Writing chemical equations Flashcards
oxygen is
O2 and not O
hydrogen if
H2 and not H
nitrogen is
N2 and not N
water is
H2O
sodium hydroxide is
NaOh
nitric acid is
HNO3
iron(II) sulfate is
FeSO4
iron(III) oxide is
Fe2O3
calcium carbonate is
CaCO3
when writing equations from worded descriptions, we have to split the formulae into
products and reactants
write the equation for: ‘when carbon dioxide reacts with calcium hydroxide, calcium carbonate and water is formed’
CO2 + Ca(OH)2 = CaCO3 + H2O
once you have figure out the formulae or the reactants and products of a reactions in an equation, you need to
balance! this is making sure that for each element, the totals are the same on the left and right of the equation
coefficients are
the numbers written in front of species when writing an equation
when writing coefficients, using
halves is sometimes acceptable, but more so in organic chemistry
the state symbols are:
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous
conventional arrows, →, show that reactions are
irreversible
the symbol ⇌ shows that reactions are
reversible
sometimes conventional arrows are lengthened to make room for writing
reaction conditions or a label to show the stage of the reaction
ionic equations show
any atoms and molecules involved, but only the ions that react together, and not spectator ions
spectator ions are
the ions in an ionic compound that do not take part in a reaction
the three-part process to follow when writing ionic equations is:
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
what is the ionic equation for the neutralisation of sodium hydroxide by dilute nitric acid
1) NaOH(aq) + HNO3(aq) → NaNO3(aq) + H2O(l)
2) Na+ + OH- + H+ + NO3- → Na+ + NO3- + H2O
3) OH-(aq) + H+(aq) → H2O(l)
ionic half-equation are written for reactions involving
oxidation and reduction
