Theoretical yield?
Maximum amount of a given product that can be formed when the limiting reactant is completely consumed.
Actual yield?
Actual amount produced in a reaction.
- Experimentally, reactions are never 100% efficient and product is lost along the way.
- Should always be smaller that theoretical yield, but can be greater in labs if measurements are not well done.
Percent yield?
% yield = (Actual yield of product/theoretical yield of product) x 100
Percent atom economy?
Ration of the molecular weight of the desired product to molecular weights (MW) of the reactants, expressed as percentage. Important for green chemistry. (Theoretical value)
% atom economy: (sum MW desired product/sum MW reactants - or total products) x 100
What is a chemical reaction?
Process by which substances are converted to different substances
Physical change?
Matter changes form but not chemical identity
Law of conversion of mass?
- Matter is neither created nor destroyed, only transferred
- Numbers, and types of atoms, are identical on both sides of the reaction
Steps for calculation masses of reactants and products in chemical reactions?
- Balance the equation for the reaction
- Convert the masses of reactants - or products - to moles
- Use the balanced equation to set up the appropriate mole ratio
- Use mole ration to calculated number of moles of the desired reactant - or product.
5.Convert from moles to masses.
*Keep in mind, what do we want, what do we know and how to get there!
Steps for stochiometry problems involving limiting reactants?
- Always write balance equation for the reaction
- Convert know masses of reactants to moles
- Use appropriate mole ratios to determine which reactant is limiting
- Compute the number of moles of the desired product
- Convert from moles to grams with molar mass, if required
Limiting reactant?
- Consumed firstly and completely
- Limits the reaction (limits the amount of product formed)
Excess reactant?
- Any reactant not completely used up after the reaction, something remains!
