Amount of Substance - Topic 5 Flashcards
What is Avogadro constant
number of particles in one mole is 6.02 x 10^23
what is molar mass
the relative molecular mass
how to work out number of moles
moles = mass / Mr
what is concentration
how many moles are dissolved per 1 dm^3 of solution
what is concentration measured in
mol dm^-3
how to work out moles with concentration
moles = conc. x volume
what is empirical formula
the smallest whole number ratio of atoms of each element in a compound
what is molecular formula
the actual number of atoms of each type of element in a molecule
what to work out % composition
mass of element / total mass
what is an ionic equation
shows the reacting particles
what does an ionic equation show
the reaction stoichiometry
what is reaction stoichiometry
the ratios of reactants to products
what is a displacement reaction
when a more reactive element reacts to take the place of a less reactive element in a compound
what are the products when a base reacts with an acid
salt and water
what is the molar gas volume
space that 1 mole of gas occupies at a certain pressure & temperature
how much is r.t.p
24 dm^3 mol^-1
how much is s.t.p
22.4 dm^3 mol^-1
how to work out moles with molar gas volume
moles = volume / molar gas volume (r.t.p or s.t.p)
long equation
PV = nRT
what is the value of R in the PV = nRT equation
8.31
what is a hazard
the potential to cause harm/damage
what is a risk
the probability of someone being harmed if they are exposed to the hazard
what is the risk assessment
how likely it is that something could go wrong, how serious it would be if it did, and ways to reduce the risk
what is titration
it allows you to find out exactly how much acid is needed to neutralise a quantity of alkali
what is uncertainity
due to the limits to sensitivity of equipment used
how to work out % uncertainty
% uncertainty = (uncertainty / reading)
x 100
state 2 ways to reduce uncertainty
- by using the most precise equipment you can
- by planning an experiment involving larger volumes of liquid
what are the 2 types of errors that can be caused
- systematic
- random
what is a systematic error
caused by the set-up or equipment (the same every time you repeat the experiment)
what is a random error
caused when reading off a scale (different every time you repeat the experiment)
how does repeating the experiment reduce the errors
reduces the random errors, by not the systematic errors
what is the theoretical yield
the mass of a product that should be made if no chemicals are lost in the process
how to work out % yield
% yield = (actual yield / theoretical yield) x 100
what is atom economy
a measure of proportion of reactant that became part of the desired product
how to work out atom % atom economy
% atom economy = (Mr of desired product / Mr of all products) x 100
what is a substitution reaction
when atoms from one reactant swap with atoms from another reactant
