Definitions
Law of Conservation of Mass
Matter cannot be created or destroyed.
HCl + NaOH -> NaCl + H2O
It is already balanced
What is the 2 in
H2O ?
Subscript
Calculate Percent yield of a reaction that should've produced 25g of product but only produced 20g.
80%
(20/25)*100= percent yield
Inaccurate weights or measurements leading to incorrect reaction amounts
Measurement errors
Yield
The amount of the product a chemical reaction produces.
Cs+N2 -> Cs3N
6Cs+N2 -> 2CsN3
What is the 3 in
3Rb + P -> Rb3P
Coefficient
Calculate Percent yield if the theoretical yield is 12.5 g of product but actual yield is 10 g.
80%
(10/12.5) * 100 = percent yield
Equipment Limitations
Products sticking to beakers or other equipment lessening the amount yielded
Products
New substances created after reaction
C + S8 -> CS2
What is 2H2 in
2H2 + O2 -> 2H2O
A reaction has a theoretical yield of 20 g of product and a percent yield of 55%. What is the actual yield?
11 g
(55/100)*20= actual yield
The reactants may not fully form or complete their reactions
incomplete reaction
Reactants
Substances you start with in an equation
Rb + S8 -> Rb2S
16Rb + S8 -> 8Rb2S
What is the 2H2O in
2H2 + O2 -> 2H2O
Product
A chemist expected 19 g of product but got 12 g. Find the percent yield.
63.16%
(12/19)*100
Products breaking down due to heat, light, or moisture before collected.
Product decomposition
Stoichiometry
Quantitative relationship between reactants and products in a chemical reaction
NH3 + O2 -> N2 + H2O
What is the middle of a chemical reaction?
2H2 + O2 -> 2H2O
Yield Arrow
This shows the reactants forming products
27
(45/100)*60
Side Reactions
Other undesired products form thus skewing and tarnishing results.