B5 how much? Quantitative analysis Flashcards
One mole =
24g
How many atoms in one mole
6x10to the power if 23
How to calculate the number if moles
Mass in g / molar mass in g
/=divide
Mnemonics for molar mass and number of moles
Never -no. Of moles
Cut- concentration
Veins- volume
What does real active atomic mass equal
Molar mass
What does conservation of mass mean
Mass of reactants = mass of products
%compositon =
G of element / g of whole composition or element x100
What % of CuO is Cu?
64/80 x100 = 80%
What does empirical formula mean
The simplest ratio between the elements
C4 h10 into the empirical formula
C2 h5
How do I get from cm to dm
Cm divided by 1000 = dm
Dm x1000 =cm
Dilution:
Volume of water to add
(Start concentration /target concentration -1 )
X start volume
Concentration is measured in …
Mol/ dm3 cubed
What is salt
Sodium chloride NaCl
Why is salt good ?
Important for nervous system
Water balance
Blood pressure
Why is salt bad?
Too much and it gives you night blood pressure
Titrations and ph indicators
What is a single indicator
One with a single colour change
What is a mixed colour indicators
One with several colour changes to show the whole ph scale
Why are single indicators better
They have an end point. This is due to the fact they they only have one colour change
Concentration=
No of moles divided by volume
What does in excess mean
To have to much in reactions it is usually the acid
What does equilibrium mean
It shows that some reactions are reversible
The reactants =the products
Changing equilibrium the temperature
All reactions are exothermic in one direction
If you decrease the temp the equilibrium with move to compensate. It will more in the exothermic direction to make more heat
If you raise the temp the equilibrium will move to decrease it. It moves in the endothermic way
Changing equilibrium pressure
This involves gas
Increase it and the equilibrium tries to reduce it by moving toward the side with the fewer moles of gas and vice versa
Changing equilibrium concentration
Increase the concentration and the equilibrium tries to decrease it by shifting to the right
And vice versa
How do you make sulphuric acid
The contact process
Step 1
Make sulphur dioxide
s +O2 = SO2
Step 2
Oxidise sulphur dioxide to make sulphur trioxide
So3. + h2O = h2 so4
Step 3
Sulphur trioxide to make sulphuric acid
So3 + h2o = h2 So4
His reaction to make sulphuric acid is what type of reaction
A reversible one
Temp of contact process
Is is exo or endothermic
What is the best temp
It is exothermic and gives out best
High temp means slower reaction
The best temp is 450 degrees
Pressure
What pressure is use
1 atmosphere is used
Increasing the pressure is expensive
The equilibrium is on the right so it’s not necessary
Catalyst
What does it change
It changes nothing with the equilibrium
To increase the rate of reaction a vanadium pentoxide catalyst
What concentration Can a strong acid have
A high or low one
WeKa vids can have what concentration
A low or high one
Name a strong acid
HCL
Name a weak acid
Ethanoic acid Ch3 COOH
What makes as strong acid strong
They ionise quickly and completely
HCL = h+ + Cl-
What makes a weak acid weak
It does not ionise completely
ch3cooh = h2 + ChOo-
Tow other strong acids
Sulphuric and nitric
What is the ph of a strong acid?
1 or 1
Electrolysis cathode is…
Negative and it gives out electrons, it loses them so it’s a minus
Electrolysis anode is….
Added electrons from the cathode
It takes the in so it’s a +
At the cathode what happens
2H+ + 2e- = H2
What happens At the anode
4OH = 2H2O + O 2-
Which electrode produces hydrogen
The cathode
Precipitation reactions what are they
It’s when two solution are mixed together and an insoluble solid is formed and precipitates out.
How do you get a precipitate on its own as a powder?
- react two solutions
- filter it
- Rinse with water
- Evaporate
Lead nitrate is added to a halide which ion is present if it turns cream?
Bromide
Lead nitrate is added to a halide which ion is present if it turns white?
Chloride
Lead nitrate is added to a halide which ion is present if it turns yellow?
Iodide
Which chemical is used to test for sulphites?
Barium chloride
What happens during a precipitate reaction?
The ions swap places
Simply what is concentration?
It’s how crowed things are
Where do you find Gide line daily amounts
On food packaging
Why are titrations used?
To find out concentrations
Rate of reaction calculations =
First reading I table at 60secs or 30secs and get it and divide by time eg.
34/60= rate of reaction gas given off per second
Strength
Tells you what proportion of the acid molecules that ionise in water
Concentration
How many moles of acid there are in a litre or dm cubed its basically how dilute or watered down the acid is
