A Level Flashcards
When can percentages shield be calculated?
Only when the substance is in excess
Why is theoretical yield hard to achieve?
- Reaction not completed
- Side reactions may have occurred
- Purification may cause loss of product
How do you calculate percentage yield?
Actual yield/theoretical yield x 100
What is the limiting reageant?
the reactant that is used up first and therefore stops the reaction
How can you tell which is the limiting reagent?
In the equation it is the substance with the most moles
What is atom economy?
The measure of how well atoms have been utilised
How do you calculate atom economy?
Sum of Mr of desired product/Mr of all products x 100
Addition reactions are always 100%
What else must be taken into account with efficiency?
Cost of reactants
Percentage yields
What is atmospheric pressure equal to?
100 kpa
What is the ideal gas equation?
PV=nRT
How do you calculate moles using volume?
Mol=V/molar gas volume
What units should be used in the ideal gas equation?
M3
K
Pa
What two assumptions does the ideal gas equation rely on?
- Intermolecular forces are negligible
2. The molecules have negligible size relative to their container
When do ideal gas equation assumptions apply?
Low pressures and high temperatures
What is the real gas equation?
(P+n2a/v2)(v-nb)=nRT
