Chemical reactions, stoichiometry, reagents
The 5 steps of stoichiometry
- Balance equation - Convert grams to moles - Write mole-to-mole ratio - Convert moles to grams - Do the math with proper units
How to find the limiting reagent:
- Balance equation - With the amount given in grams, determine how many moles of each reactant is present - Whichever reactant produces the least amount of product is your limiting reagent. (The other is in excess)
Standard temperature
0 degrees Celsius (273.15 K)
Look at the following reaction: ___Zn + ___HCl ==> ___ZnCl₂ + ___H₂ Balance it and find how many grams HCl are needed to react with 8.25g Zn. (Hint: use the 5 steps)
1 Zn + 2 HCl ==> 1 ZnCl₂ + 1 H₂; 9.21g HCl
Standard pressure
1 atm
When we combust a hydrocarbon or carbohydrate, which two elements are always produced?
Carbon dioxide and water
When balancing chemical equations, which elements should be balanced last?
Hydrogen and Oxygen
Stoichiometry
The calculation of quantities in chemical reactions
combustion reaction
rapid combination with oxygen, leads to burning.
STP
standard temperature and pressure
theoretical yield
the maximum amount of product that could be formed from given amounts of reactants
actual yield
the measured amount of a product of a reaction
limiting reagent
the reactant that determines the amount of product that can be formed in a reaction (used up first)
synthesis reaction
two or more substances combine to form another substance
Molar volume of all gases at STP
22.4 L
Look at the balanced equation: 2 Al + Fe₂0₃ ==> 2 Fe + Al₂0₃ If there are 25 mole of aluminum, how many mole of iron would be produced? How many moles Fe₂O₃ would you need?
25 moles Fe; 12.5 moles Fe₂o₃
Single Replacement
A + BC --> B + AC (Metals)
double replacement
AB + CD = AD + CB (Metals)
decomposition reaction
a reaction in which a single compound breaks down to form two or more simpler substances
Neutralization reaction
a reaction in which an acid and a base react in an aqueous solution to produce a salt and water
Percentage yield
actual yield divided by theoretical yield x 100%
How to find theoretical yield
limiting reagent of the element in moles * molar mass of the compound
