11 Chemistry - Stoichiometry Flashcards
Define: mole / avogadro’s constant
(6.02X10^23) things
How many molecules 1 mole of hydrogen gas has?
(6.02X10^23)
How many moles is:
a) 3.01 X 10^23 =
b) 18 X 10^22 =
a) 0.5 moles
b) 0.299 moles
how many
_________ = moles
avogadro
How many is:
a)2.8 moles of h2?
a) 1.6856 x 10^24
moles x avogadro = how many
If I have 0.5 moles of CuSO4
a) how many molecules of copper sulphate are there?
b) how many oxygen atoms are there?
a) 0.5(avogadros) = 3.01x10^23
b) (3.01x10^23) x 4 = 1.204 x 10^24
What is the atomic mass (Ar) of an atom equal to?
It is equal to the mass on grams of one mole of that element
eg. copper, Cu, has an atomic mass of 64, this means one mole of Cu is 64g
What is the molecular mass (Mr) of a compound equal to?
It is equal to the mass of one mole of a compound
eg. NaCl Na = 23 Cl = 33.5
so NaCl = 23+33.5
= 58.5g is the mass of one mole of NaCl
Find the mass of one mole of:
a) methane CH4
b) Ethanic acid CH3COOH
c) Glucose
a) 16g
b) 60g
c) 180g
Equation for moles and mass
mass mass
Moles = _______ moles formula mass
Ar or Mr
What is concentration?
The amount of solute in a given volume of solution
What is the unit for concentration?
mol dm^-3 or (mol/dm^3)
What is the equation for concentration?
moles vol(dm^3)
concentration = \_\_\_\_\_\_\_\_ moles 24dm^3
volume(dm^3)How much is 1 dm^3?
1 litre
At room temp, what is the volume of 1 mole of any gas?
24dm^3
At 0°C, what is the volume of 1 mole of any gas?
22.7dm^3
Equation for moles in gases
volume volume
moles of gas = ________ moles 24dm^3
24dm^3
equation of combustion
something + 2oxygen –> carbon dioxide + water
If i burnt 10g of methane, what mass of oxygen would be needed?
1) 10/16 = 0.625 moles of methane
2) We know from the combustion equation that every 1 molecule of methane reacts with 2 of oxygen
so, 0.625 x 2 = 1.25 moles of oxygen
3) moles x Mr = mass
1. 25 x 32 = 40g of oxygen
What are all equations that link moles, to mass, to gas volume, to concentration?
mass volume moles
moles Mr moles 24dm^3 concentration 24dm^3
What does an acid + base give?
Give an example with hydrochloric acid and sodium hydroxide
acid + base = neutralisation
hydrochloric acid + sodium hydroxide = water + salt
What is the relative atomic mass (Ar)?
the weighted average of all isotopes of an element, compared to carbon 12
What is relative formula mass (Mr)?
the combined mass of the atoms in a compound, compared to carbon 12
What do these symbols mean?
a) (g)
b) (s)
c) (aq)
d) (l)
a) (g) gas
b) (s) solid
c) (aq) aqueous - dissolved in solution
d) (l) liquid
What does limiting reagent and excess reagent mean?
Limiting - the one you have less of, the one that is all used up, how much is produced depends on it
Excess - the one you have more of, still some left at then end but in smaller amount
