Formula, Equations and Amount of Substances - topic 5 Flashcards
Definition of Relative Atomic Mass
the average mass of one atom compared to 1/12 the mass of an atom of carbon-12
Define Molecular Mass
the average mass of a molecule compared to 1/12 of the mass of one atom of carbon-12
What is water of crystallisation?
water that is chemically bonded into a crystal structure
What is the ideal gas equation?
PV = nRT
What is P
Pressure in pascals
What is V
Volume in m3
(to convert from cm3 - m3, divide by 10^6)
(to convert from dm3 - m3, divide by 10^3)
What is n
moles
What is R
Gas constant - 8.31 Jmol-1k-1
What is T
Temperature - measured in K
(to get from celsius to k, add 273)
Why is the yield not always 100%?
- Side reactions
- Incomplete reaction
- Loss on transfer
What is the dilution equation?
C1 x V1 = C2 x V2
(the concentration and the volume of what you started with has to be the same as the concentration and volume of what you end with)
What is the %uncertainty equation?
(uncertainty of equipment/measurement made on apparatus) x 100
Where do we find uncertainties?
In all pieces of equipment (a scale could have an uncertainty of +- 0.001 grams)
When is our answer more accurate?
When the uncertainty is smaller
How do we reduce any uncertainty?
- We want our equipment to have a higher resolution (more decimal places)
- We could take a larger measurement
