1.1-1.12
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define isotope
atoms of the same element with the same number of protons but a different number of neutrons
define relative isotopic mass
the mass of a single isotope of and element relative to 1/12 the mass of 1 atom of carbon 12
define relative atomic mass
the average mass of an atom of an element relative to 1/12 the mass of one atom of carbon 12
what is mass spectrometry
an accurate way of measuring the mass of atoms and molecules
define relative molecular mass
the average mass of a molecule compared to 1/12 the mass of one atom of carbon 12
define Avogadro’s constant
the number of atoms or molecules in one mole of a substance
what is an empirical formula
the simplest whole number ration of elements in a compound.
which transition metals only have one possible charge
silver- Ag^+ zinc- Zn^2+
what is a salt
an ionic compound formed when an acid reacts with a base
what is the water of crystallisation
the water molecules contained withing hydrated salts. this can be removed using heat to get anhydrous salt compounds
how is a hydrated salt turned into an anhydrous salt
by heating the hydrated salt to constant mass.
how is the degree of hydration determined?
from the mass of the hydrated salt before and after heating to constant mass. form this the mass of water is calculated, the moles of the salt and water is calculated, then the molar ratio gives you the number of water molecules per salt molecule in the hydrated salt
what is concentration
the amount of solute in a given volume of solvent
what is the limiting reagent
the reactant that is not in excess that will be used up first, stopping the reaction
what is Avogadro’s law
at the same temperature and pressure, one mole of any gas has equal volumes
whats the volume of gas at RTP (also what is RTP)
room temperature and pressure: 100,000 Pa 25°C 24dm^3
factors affecting the volume of a gas
• the number of moles. directly proportional • the pressure. inversely proportional • temperature. directly proportional
the 3 factors that make the ideal gas equation invalid
• if pressure is too high, • if the temperature is too low, • if the molecules are too large
whats the percentage yield?
the percentage of the theoretical yield actually achieved
what is the percentage atom economy
the percentage by mass of reactants that end as the desired product. the higher the value the less waste material.
why is the theoretical yield not the actual yield
• impurities in the reactant • loss of materials in the apparatus • side reactions
whats a precipitation reaction
a reaction between two aqueous solutions producing an insoluble product
how is an ionic equation written
the spectator ions are removed from the equation. (spectator ions don’t take part in the reaction)
solubility table
all sodium/potassium/ammonium salts are soluble, all nitrates are soluble, most chlorides are soluble (excluding silver/lead) most sulphates are soluble (excluding strontium/lead/barium most hydroxides are insoluble (except Na/K/NH4^+) most carbonates are insoluble (except Na/K/NH4^+)