CHEM 1011 EVALUATION EXAM UPDATED QUESTIONS AND
SOLUTIONS RATED A+
✔✔What occurs if the reactant concentration is larger than product concentration - ✔✔K
will be small/less than one; and it will favor the reactants (large denominator and small
numerator)
✔✔Le Chatelier's Principle - ✔✔States that if a stress is applied to a system at
equilibrium, the system shifts in the direction that relieves the stress.
✔✔Change that will occur with an increase in reactant concentration or decrease in
concentration of product - ✔✔shifts to the right (products)
✔✔change that will occur if decrease in reactant concentrations or an increase in
concentration of products - ✔✔shifts left (reactants)
✔✔change that occurs with an increase in temperature in an exothermic reaction -
✔✔shifts left
✔✔change that occurs with a decrease in temperature in an exothermic reaction -
✔✔shifts right
✔✔change that occurs in an endothermic reaction with an increase in temp - ✔✔shifts
right
✔✔change that occurs in an endothermic reaction with a decrease in temp - ✔✔shifts
left
✔✔change that occurs with a decrease in pressure (for gases) - ✔✔shifts towards sides
with more gas molecules
✔✔change that occurs with an increase in pressure (gases only) - ✔✔shifts towards the
side with less gas moles
✔✔Q vs K - ✔✔Q = K => system remains at equilibrium
Q >K => reverse reaction will occur
Q < K =>forward reaction will occur
✔✔Acids - ✔✔proton donors; have a sour taste and react with bases; may be corrosive
to metals and cause severe burns on contact with skin
✔✔bases - ✔✔proton acceptor; tastes bitter, feels slippery and reacts with acidds, feels
slippery to the skin
, ✔✔pH scale - ✔✔a convenient way to measure the aciditiy of a solution
✔✔acidity - ✔✔a measure of the amount of dissolved hydronium ions; the greater
number of hydrogen ions in a solution = the more acidic the solution
pH=-log[H+]
✔✔Measurements of bases - ✔✔based on hydroxide ions; the pH value of a base
increases as the amount of hydroxide ions in the solution increases as there is a
decrease in amount of hydrogen ions in a solution
✔✔pH indicator - ✔✔changes color at a specific pH and allows you to measure the pH
of a substance; each indiciator changes color within a well-defined pH ranges
** this allows for us to se the moment when the analyte has completely reacted with the
titrant
✔✔acid ionization constant (Ka) - ✔✔the equilibrium constant for a reaction in which an
acid donates a proton to water to form a hydronium ion and a conjugate base
**the larger the value of Ka = the stronger the acid
✔✔base ionization constant - ✔✔the equilibrium constant for the reaction of a weak
base with water, which forms a hydroxide ion and conjugate acid
✔✔Strong Acid vs weak acid - ✔✔strong acid=completely ionizes in water, forming a
conjugate base that is weaker than water
weak acid=only partially ionizes in water forming a stronger base than water
✔✔equivalence point - ✔✔the point at which the two solutions used in a titration are
present in chemically equivalent amounts
=when exactly enough base (titrant) has been added to completely react with the acid
(analyte)
=identified by a dramatic increase in pH
✔✔half equivalence point - ✔✔the mement when the exact volume of strong base has
been titrated into the weak acid, to convert half the weak acid into its conjugate base;
conc of weak acid = conc of conjug base
- pKa = pH
✔✔titration - ✔✔a measured amount of a solution of unknown concentration is added to
a known volume of a second solution until the reaction between them is just complete
✔✔Phenolpthalein - ✔✔ph indicator taht turns bright pink at a basic pH of 8.2 and
higher
SOLUTIONS RATED A+
✔✔What occurs if the reactant concentration is larger than product concentration - ✔✔K
will be small/less than one; and it will favor the reactants (large denominator and small
numerator)
✔✔Le Chatelier's Principle - ✔✔States that if a stress is applied to a system at
equilibrium, the system shifts in the direction that relieves the stress.
✔✔Change that will occur with an increase in reactant concentration or decrease in
concentration of product - ✔✔shifts to the right (products)
✔✔change that will occur if decrease in reactant concentrations or an increase in
concentration of products - ✔✔shifts left (reactants)
✔✔change that occurs with an increase in temperature in an exothermic reaction -
✔✔shifts left
✔✔change that occurs with a decrease in temperature in an exothermic reaction -
✔✔shifts right
✔✔change that occurs in an endothermic reaction with an increase in temp - ✔✔shifts
right
✔✔change that occurs in an endothermic reaction with a decrease in temp - ✔✔shifts
left
✔✔change that occurs with a decrease in pressure (for gases) - ✔✔shifts towards sides
with more gas molecules
✔✔change that occurs with an increase in pressure (gases only) - ✔✔shifts towards the
side with less gas moles
✔✔Q vs K - ✔✔Q = K => system remains at equilibrium
Q >K => reverse reaction will occur
Q < K =>forward reaction will occur
✔✔Acids - ✔✔proton donors; have a sour taste and react with bases; may be corrosive
to metals and cause severe burns on contact with skin
✔✔bases - ✔✔proton acceptor; tastes bitter, feels slippery and reacts with acidds, feels
slippery to the skin
, ✔✔pH scale - ✔✔a convenient way to measure the aciditiy of a solution
✔✔acidity - ✔✔a measure of the amount of dissolved hydronium ions; the greater
number of hydrogen ions in a solution = the more acidic the solution
pH=-log[H+]
✔✔Measurements of bases - ✔✔based on hydroxide ions; the pH value of a base
increases as the amount of hydroxide ions in the solution increases as there is a
decrease in amount of hydrogen ions in a solution
✔✔pH indicator - ✔✔changes color at a specific pH and allows you to measure the pH
of a substance; each indiciator changes color within a well-defined pH ranges
** this allows for us to se the moment when the analyte has completely reacted with the
titrant
✔✔acid ionization constant (Ka) - ✔✔the equilibrium constant for a reaction in which an
acid donates a proton to water to form a hydronium ion and a conjugate base
**the larger the value of Ka = the stronger the acid
✔✔base ionization constant - ✔✔the equilibrium constant for the reaction of a weak
base with water, which forms a hydroxide ion and conjugate acid
✔✔Strong Acid vs weak acid - ✔✔strong acid=completely ionizes in water, forming a
conjugate base that is weaker than water
weak acid=only partially ionizes in water forming a stronger base than water
✔✔equivalence point - ✔✔the point at which the two solutions used in a titration are
present in chemically equivalent amounts
=when exactly enough base (titrant) has been added to completely react with the acid
(analyte)
=identified by a dramatic increase in pH
✔✔half equivalence point - ✔✔the mement when the exact volume of strong base has
been titrated into the weak acid, to convert half the weak acid into its conjugate base;
conc of weak acid = conc of conjug base
- pKa = pH
✔✔titration - ✔✔a measured amount of a solution of unknown concentration is added to
a known volume of a second solution until the reaction between them is just complete
✔✔Phenolpthalein - ✔✔ph indicator taht turns bright pink at a basic pH of 8.2 and
higher
