C3.1 Theory Flashcards
Law of conservation of mass
In chemicals reactions, mass cannot be created nor destroyed
What happens to the mass of the product in a reaction with a closed system
the total mass will be the same at any point in time in any closed system.
What happens to the mass of the product in a reaction with a non closed system
Mass will be lost, not destroyed and is often lost as a gas
What is combustion
Combustion is a chemical process or a reaction between Fuel (Hydrocarbon) and Oxygen
Explain, in terms of particles, why the mass of substances increases after a combustion reaction
-> When a substance (eg copper) is heated up, the particles gain enough energy to react with the oxygen atoms in the air around it.
-> These atoms then become part of the copper oxide molecules that form when copper reacts with oxygen. This increases the overall mass
What do balanced equations show
- how the atoms are rearranged in a reaction
- the relative amounts of each substance involved
State symbols
Liquid - (l)
Solid - (s)
Gas - (g)
Aqueous - (aq)
What are half equations
A half equations is a model for the change that happens to one reactant in a chemical reaction
What is an ionic reaction
A complete ionic equation shows the ions taking part in the reaction
What are spectator ions
Ions that don’t take part in a chemical reaction
What is a net ionic equation
An equation where the spectator ions are cancelled out, leaving only the ions that are used in the equation behind
When writing a net ionic equation what do you split
You split ONLY the AQUEOUS compounds
How to know if a compound is aqueous
- ANY compound with NITRATE (NO3-) is AQUEOUS
- ANY halogen bonded with any other metal except SILVER, LEAD AND MERCURY is aqueous
Silver fluoride is soluble in water
What is a precipitation reaction
When 2 aqueous compounds react together to forma a solid compound
Eg
Aqueous Pb(NO3)2 and aqueous KCl react to form solid PbCl2
Sodium hydroxide reacts with hydrochloric acid. Sodium chloride and water are made.
NaOH + HCl → NaCl + H2O
What mass of sodium hydroxide would be needed to make 46.8 g of sodium chloride
32g
Methane burns in oxygen to form carbon dioxide and water.
CH4 + 202 → CO2 + 2H20
Calculate the amount of carbon dioxide made when 6.4 g of methane is burnt.
17.6 grams
Calcium carbonate thermally decomposes to make calcium oxide and carbon dioxide.
CaCOз → CaO + COг
Calculate the mass of calcium carbonate needed to make 209g of calcium oxide.
(Ar: Ca = 40.1, C = 12.0, 0 = 16.0)
Give your answer to 3 significant figures.
373g
