formulae, equations and hazards Flashcards
recall the formulae of elements, simple compounds and ions
simple compounds: ammonia NH(3), hydrogen H(2), chlorine = Cl(2), oxygen O(2), water H(2)O, carbon dioxide CO(2)
ions: ammonium = NH(4)+, nitrate = NO(3)-, sulfate = SO(4)2-, hydroxide = OH-, carbonate = CO(3)2-
how to write word equations
not the same as chemical this one has words
left hand side show reactants (as they react with each other),
right hand side are products (produced from reactants)
ex methane burns in oxygen giving carbon dioxide and water
methane + oxygen -> carbon dioxide + water
write balanced chemical equations, including the use of the
state symbols (s), (l), (g) and (aq)
- find element that needs balancing (not same on both sides)
- may create another imbalance so carry on balancing
ex H(2)SO(4) + NaOH = Na(2)SO(4) + 2H(2)O
put 2 in front of NaOH and everything is balanced
s=solid g=gas aq=aqueous l=liquid
write balanced ionic equations
write ionic equations for reactions involving ions
only reacting particles and products formed are included
1. look at balanced symbol equation and take out any aqueous ions that are present on both sides of the equation.
ex write ionic equation for this reaction
CaCl(2) aq + 2NaOH aq -> Ca(OH)(2) s + 2Na Cl aq
1. anything ionic and aqueous will break up into its ions in the solution, so write out the equation showing all the aqueous ions separately
Ca2+aq + 2Cl- aq + 2Na+ aq +2OH- aq -> Ca(OH)(2) s + 2Na+ aq +2Cl- aq
2. to get the ionic equation cross out anything that’s the same on both sides
so Na+ and Cl- ions
should get Ca(2)+ aq + 2OH- aq -> Ca(OH)(2) s
*overall charge should be the same on both sides
Describe the use of hazard symbols on containers to indicate the dangers associated with the contents
oxidising - provides oxygen so other materials can burn more fiercely
harmful - irritation, reddening or blistering
environmental hazard - harmful to
environment or organisms
highly flammable - catches fire easily
toxic - can cause death
corrosive - destroys materials like living tissues (eyes and skin)
describe the use of hazard symbols on containers to inform people about the safe-working precautions with these substances in the laboratory
when planning an experiment you need to identify the hazards and the risks from the hazards. including doing a risk assessment by seeing how likely it is for something to go wrong an how serious it would be if it did
Evaluate the risks in a practical procedure and suggest suitable
precautions for a range of practicals including those mentioned
in the specification
hazard symbols show if the chemical is dangerous for you
possible precautions are: wear gloves, lab coat, goggles, use as low concentrations of substances as possible
ex hydrochloric acid and sodium hydroxide are harmful at low concentration sand corrosive eat high concentrations, to reduce risk wear goggles lab coat and gloves.
