Reactivity 2.1 Flashcards
Why is there no overall change of mass in a chemical reaction?
Because there is a fixed relationship between the number of reactant particles and the number of product particles (stochiometry)
What are used to balance chemical equations?
Stoichiometric coefficients (gives the molar ratio)
Gas volume is determined by….
Only the no. of particles and by the temp and pressure
Molar Volume (V_m)
The volume occupied by one mole of any gas
Molar volume must be______ for all gases under ________
- The same
- The same conditions of temp and pressure
When is a back titration used?
When the end point is hard to identify or when one of the reactants is impure.
How is a back titration done?
A known excess of one of the reactants is added to the reaction mixture, and the unreacted excess is then determined by titration against a standard solution. By subtracting the amount of unreacted reactant from the original amount used, the reacting amount can be determined.
Limiting reactant/ limiting reagent
The reactant that runs out first. It determines the amount of product that can be formed
Theoretical yield
The max amount of product that can be formed according to the balanced eq
Experimental yield
The actual amount of product obtained when the experiment is performed
Percentage yield
The experimental yield divided by the theoretical yield expressed as a percentage
What can cause the experimental yield to be lower than the theoretical yield?
- side rxns occuring
- decomposition of reactants and/or products
- loss of product during purification
- reversible chemical rxns preventing process completion
- an incomplete rxn
What can cause the experimental yield to be higher than the theoretical yield?
- impurities in a product
- when a product has not been fully dried
- an incomplete rxn
Standard solution
A solution of a known conc
Green/ sustainable chemistry
An approach to chemical research and manufacture that tries to minimise the production and release of hazardous substances, inc solvents used.
