3.1.2 Amount Of Substances Flashcards
Equation moles avogadro’s constant particles
Number of particles = Number of moles x Avogadro’s constant
Particles can be ions electrons atoms molecules etc
Equation moles , mass , Mr
Moles = Mass/Mr
How many particles is 1 mole
6.02 x 10^23
Equation Mass/ Moles, Concentration, Volume
Moles/Mass = Concentration x volume (dm^3)
What is the ideal gas equation + units
pV=nRT
p- pressure (Pa)
V- volume m3
n- number of moles
R - gas constant ( 8.31 JK^-1 mol^-1)
T p- temperature Kelvin
What is the name of this equation pV=nRT
The IDEAL gas equation
How to convert KPa into Pa
X 1000
How to convert between degrees and kelvin
0=273 kelvin
Just add onto both
E.g.
25= 273 + 25
25= 298
How to convert dm3 to m3
Divide by x10^3
Describe how to make a volumetric solution
Stage 1
Weight sample in weighing boat in mass balance
Transfers to beaker
Re weight record mass difference
Stage 2
Add deionised water
Stir with a glass rod
Until solid has dissolved
Stage 3
Transfers to volumetric flask with a 250cm^3 marking
With washings fill up to 250cm^3 mark
Invert flask
What is theoretical yield
Is the mass of product that can be formed assuming no chemical are lost in the process
Theoretical yield equation
Moles x Mr
In atom economy is the big number used
YES
Atom economy equation
Mr of desired product / sum of Mr of ALL products
Define relative molecular mass
Mass of 1 atom of carbon 12
Define molecular formula
Number of atoms of each element in a molecule
Define empirical formula
Simplest ratio of atoms of each element
Does empirical formula have to be not whole numbers?
NO
MUST BE WHOLE NUMBER
Why is the percentage yield not 100%
- other reactions took place simultaneously
- the reaction does not go to completion
- reactants or products are lost to the atmosphere
Define meaning of mole
Avogadro’s number of molecules
Define relative atomic mass
The average mass of an atom of an element when compared with 1/12th of the mass of an atom of carbon 12
Formula of sulphur
S8
For any acid formula what element is always present
Hydrogen
The student rinses the burette with deionised water before filling with sodium hydroxide solution. State and explain the effect, in any, that rinsing will have on the value of the titre.
The titre value would increase because the sodium hydroxide solution would be dilute
What units for percentage yield equation moles or grams
Both
Percentage yield equasion
% Yield = yield /max theoretical yield
Which compound would require the greatest amount of oxygen for complete combustion of 1 mole of the compound
The one with the highest ration of carbon to oxygen atoms. They require more oxygen to combine with those carbons and can’t utilise the oxygen within its structure as much
% uncertainty equasion
= ( Uncertainty/ mass added) x100
% uncertainty equasion
= ( Uncertainty/ mass added) x100
Why is percentage yield important
Getting as much product from the reaction as possible
Why is percentage atom economy important
The maximum amount of atoms end up in the desired product
Formula of anything hydroxide
X OH
Give a reason why bond enthalpy found is different to bond enthalpy in data book
Data book value derived from different compounds
Percenatge uncertainty equation
Uncertainty/ measurement x100
Reactivity down group 2
Increases
