Topic 3- Quantative Chemistry Flashcards
1
Q
Percentage mass of an element in a compund
A
Ar/ Mr of compund x 100
2
Q
Moles =
A
Mass/ Mr
3
Q
Empirical Formula
A
Elements Mass (/Ar) Moles (/smallest) Ratio
(Ratio tells you empirical formula)
4
Q
Mass from Molar Ratio
A
Ratio (mol:mol)
Moles (g/Mr)
Actual Ratio (mol:mol)
Grams (Moles x Mr)
5
Q
Concentration
A
C1V1= C2V2
/n1 /n2
6
Q
Concentration (triangle)
A
Concentration= no of moles/ Volume
7
Q
Step by Step concentration
A
1) find moles of known substance (mol=conc.x volume)
2) use molar ratio to find moles of unknown substance
3) find concentration (conc.= mol/volume)
8
Q
Atom Economy
A
Mr of desired/
Mr of reactants X100
9
Q
Percentage Yield
A
Mass of products made/
Max theoretical mass X100
*use the masses of the CORRECT product
10
Q
Why is the percentage yield never 100%
A
- Not all reactants react to make a product
- There might be side reactions
- Product is lost when separated from reaction liquid
