CHEM 162 EXPERIMENT 2 ELECTROCHEMISTRY
COMPREHENSIVE TEST PAPER 2026
COMPLETE QUESTIONS AND ANSWERS
EXPERT VERIFIED GRADED A+
◉ The color of methyl green fades under ____ (acidic/basic)
conditions. The reaction is ______(faster/slower) as conditions
continue in this fashion (as the dye fades). Answer: basic; faster
◉ net reaction involving Na2HPO4 and Na3PO4 buffer system
(experiment 2 - rate of decolorization) Answer: PO4^3- + H2O(l) -
><- HPO4^-2 + OH^-
◉ What order is the reaction involving Na2HPO4 and Na3PO4 buffer
system? (experiment 2 - rate of decolorization) Answer: first order
with respect to the dye
◉ what is the observed rate law for the reaction involving Na2HPO4
and Na3PO4 buffer system? (experiment 2 - rate of decolorization)
Answer: rate = k1 [dye][H2O] + k2[dye][OH-] or [dye]x(k_obs)
◉ When a reaction is first order, but [h2O]>>[dye] , what will
happen? What will the observed rate constant be in this case?
Answer: the reaction will be pseudo first order
,k (obs) = k1[H2O] + k2[OH-]
◉ Beer-Lambert Law Answer: A= elc
◉ define each variable in the Beer-Lambert Law Answer: A=
absorbance
e = molar absorptivity (constant)
l = cell path length (constant)
c = concentration
◉ equation relating the absorbance to the rate constant (k _obs)
Answer: -ln(A) =K_obs*t - ln(A_o)
◉ when plotting -ln(A) v time, what is the slope equal to? Answer:
k_obs
◉ biological application of methyl green Answer: staining DNA
◉ Lewis acid Answer: a compound or ionic species that can accept
an electron pair from a donor compound
, ◉ Lewis base Answer: a compound or ionic species that can donate
an electron pair to an acceptor compound
◉ How could you find the concentration of OH- for multiple trials in
an experiment? Answer: - find k or kb equation and solve for [OH-]
◉ Why is the slope of K_obs vs. [OH-] equal to k2?
(given kobs = k1[h2o] + k2[oh-]) Answer: because k1[h2o] remained
constant experimentally (volume of h2o never changed) and
therefore doesn't affect the slope
◉ Describe an experiment that would examine the effect of
increased ionic strength on the observed rate constant. Answer:
Adding another salt to the experiment would increase ionic strength,
but decrease the observed rate constant.
◉ the molar concentration of a reactant will ______(increase/
decrease) over time and the molar concentration of product will
_____ (increase/ decrease). Answer: decrease; increase
◉ catalysis Answer: the increase int eh rate of a chemical reaction
due to the participation of a substance called a catalyst
◉ catalyst Answer: lowers the activation energy of a reaction; allows
reaction to proceed at a faster rate or under different conditions
COMPREHENSIVE TEST PAPER 2026
COMPLETE QUESTIONS AND ANSWERS
EXPERT VERIFIED GRADED A+
◉ The color of methyl green fades under ____ (acidic/basic)
conditions. The reaction is ______(faster/slower) as conditions
continue in this fashion (as the dye fades). Answer: basic; faster
◉ net reaction involving Na2HPO4 and Na3PO4 buffer system
(experiment 2 - rate of decolorization) Answer: PO4^3- + H2O(l) -
><- HPO4^-2 + OH^-
◉ What order is the reaction involving Na2HPO4 and Na3PO4 buffer
system? (experiment 2 - rate of decolorization) Answer: first order
with respect to the dye
◉ what is the observed rate law for the reaction involving Na2HPO4
and Na3PO4 buffer system? (experiment 2 - rate of decolorization)
Answer: rate = k1 [dye][H2O] + k2[dye][OH-] or [dye]x(k_obs)
◉ When a reaction is first order, but [h2O]>>[dye] , what will
happen? What will the observed rate constant be in this case?
Answer: the reaction will be pseudo first order
,k (obs) = k1[H2O] + k2[OH-]
◉ Beer-Lambert Law Answer: A= elc
◉ define each variable in the Beer-Lambert Law Answer: A=
absorbance
e = molar absorptivity (constant)
l = cell path length (constant)
c = concentration
◉ equation relating the absorbance to the rate constant (k _obs)
Answer: -ln(A) =K_obs*t - ln(A_o)
◉ when plotting -ln(A) v time, what is the slope equal to? Answer:
k_obs
◉ biological application of methyl green Answer: staining DNA
◉ Lewis acid Answer: a compound or ionic species that can accept
an electron pair from a donor compound
, ◉ Lewis base Answer: a compound or ionic species that can donate
an electron pair to an acceptor compound
◉ How could you find the concentration of OH- for multiple trials in
an experiment? Answer: - find k or kb equation and solve for [OH-]
◉ Why is the slope of K_obs vs. [OH-] equal to k2?
(given kobs = k1[h2o] + k2[oh-]) Answer: because k1[h2o] remained
constant experimentally (volume of h2o never changed) and
therefore doesn't affect the slope
◉ Describe an experiment that would examine the effect of
increased ionic strength on the observed rate constant. Answer:
Adding another salt to the experiment would increase ionic strength,
but decrease the observed rate constant.
◉ the molar concentration of a reactant will ______(increase/
decrease) over time and the molar concentration of product will
_____ (increase/ decrease). Answer: decrease; increase
◉ catalysis Answer: the increase int eh rate of a chemical reaction
due to the participation of a substance called a catalyst
◉ catalyst Answer: lowers the activation energy of a reaction; allows
reaction to proceed at a faster rate or under different conditions
