Unit 2 - Equilibrium Part 1

Question 1

Titrant

Answer 1

a reagent that we add to the titrand. Usually the solution in the burette. The concentration is known

Question 2

Analyte/titrand

Answer 2

the solution with an unknown concentration

Question 3

Acid-base titrations

Answer 3

acidic or basic titrant reacts with a titrand that is an acid or base

Question 4

Complexometric titrations

Answer 4

based on metal-ligand complexation

Question 5

Redox titrations

Answer 5

the titrant is an oxidizing or reducing agent

Question 6

Precipitation titrations

Answer 6

titrand and titrant form a precipitate

Question 7

Equilibrium constant

Answer 7

the ratio of the concentrations of products and reactants when there is no net change in the system such that the rate of the forward reaction equals that of the reverse reaction

Question 8

Bronsted-Lowry definition of acids and bases

Answer 8

Acids donate a proton to water to generate hydronium ion

Bases accept a proton from water to generate hydroxide

Question 9

Charge balance

Answer 9

an algebraic statement of electroneutrality of the solution. The sum of the positive charges in solution equals the sum of the negative charges in solution so that the solution is electrically neutral

there should only be one charge balance equation regardless of how many equilibria occur simultaneously

Charged spectator ions need to be included

Question 10

Mass balance

Answer 10

statement of the conservation of matter. The sum of the amounts of species in a solution containing a particular atom (or group of atoms) must equal the amount of that atom (or group) delivered to the solution

the number of each type of atom at equilibrium must equal the number initially present/added to the system

Question 11

Amphiprotic

Answer 11

when a molecule can act as both an acid or a base

Question 12

Formal concentration

Answer 12

notated with the symbol “F”, and are formula weights per liter of solution

Question 13

Formula weight

Answer 13

the weight of a mole of the substance

Question 14

Difference between formal and molar

Answer 14

formal concentration indicates moles of the original chemical formula in solution without regard for the species that actually exists in solution

molar concentration is the concentration of a particular species in solution

Question 15

Systematic way of solving eq’m problems

Answer 15

1) write all relevant reactions
2) write the charge balance equation
3) write the mass balance equations
4) write the eq’m constant for each chemical reaction
5) count the equations and unknowns. You should have as many equations as unknowns (chemical species)
6) solve for all the unknowns

Question 16

Using approximations as a function of the concentration of HCO3 -

Answer 16

the higher the concentration, the lower the error

Question 17

How the composition of a polyprotic acid system is affected by pH

Answer 17

the more the polyprotic acid dissociates, the lower the Ka value will be for every equilibrium (it will be harder for the H3O+ to dissociate)

Question 18

Alpha diagram

Answer 18

a graphical representation of how pH affects the relative abundances of polyprotic acids and their conjugate bases

Question 19

Zwitterion

Answer 19

a molecule that has 2 separate positive and negative charge

Question 20

Isoelectric pH

Answer 20

the point where a molecule carries no net electric charge or is electrically neutral in the statistical mean

we can use isoelectric pH to separate amino acids (or proteins made from amino acids) based on their isoelectric point

negative ions shift to the left and positive ions shift to the right. An analyte with a net negative charge will migrate towards the positive anode (right) and gets protonated. Migration ceases when its net charge is zero (this is its isoelectric point)