C5.1: Monitoring Chemical Reactions Flashcards
Define theoretical yield
The maximum possible mass that can be made during a reaction
What is the formula of theoretical yield?
(Mass of limiting / sum of Mr of limiting) x Mr of product
What is the actual yield?
The mass of the product actually obtined from the reaction
Usually less than the theoretical yield
Why is the actual yield usually less than theoretical yield?
Incomplete reactions, some reactions do not react
Practical losses, during pouring or filtering
Side reactions, unwanted products/reactions
How can you calculate percentage yield?
( Actual yield / theoretical yield ) x 100
What is atom economy?
A measure of how many reactant atoms form a desired product
Atom economy formula
(Total molar mass of desired product / total mr of all reactants) x 100
Why must manufacturers make sure they make a profit when producing substances?
They will go out of business
What factors should chemical engineers consider when choosing a reaction pathway?
Yield of the product
Atom economy of a reaction
Usefulness of product/byproducts
Rate of reaction
Equilibrium position
What is a byproduct
A substance formed in a reaction in addition to the desired product. They are sometimes useful and can be sold but others may be wasteful
How can we go from cm3 to dm3?
Divide by 1000
How can we go from dm3 to cm3?
Multiply 1000
What are the 2 units for concentration?
g/dm3
mol/dm3
What is titration?
A technique where a solution of known concentration is used to determine the concentration of an unknown solution
What is the method for titration?
Use a pipette to add 25cm3 of dilute sodium ydroxide solution to a clean conical flask
Add a few drops of phenolphthalein indicator to the conical flask, then put the flask on a white tile
Fill the burette with dilute hydrochloric acid and note the starting volume
Slowly add acid from burette to conical flask swirling to mix
Stop adding acid at the point when colour permanently changes from colourless to pink. Note final volume reading
Repeat 1-5 until you get concordant titres
How to calculate gas volume in dm3?
Amount in mol x 24dm3 / mol
