Units, conversions, etc.
Accuracy, precision, and sig figs
Equilibrium
Activities
Monoprotic Acids/bases
100
When using temperature in calculations, what units are used?
Kelvin (K)
100
A pH probe was calibrated incorrectly causing the pH readings in your experiment to always be 0.2 pH units too high. Is this an example of systematic or random error?
Systematic error
100
What compounds are not included in equilibrium expressions?
Pure solids and liquids
100
As ionic strength increases, what happens to the activity coefficient?
The activity coefficient decreases
100
Calculate the Kb for acetic acid if the Ka for acetic acid is 1.76 x 10-5. (Kw = 1.01 x 10-14)
5.74 x 10-10
200
Convert 4 nM to pM
4000 pM
200
Write the answer for the following logarithm using the correct number of sig figs.
-log(0.0564) = _____
1.282 # of sig figs in log expression translate to the number of decimal places in the answer
200
Write the equilibrium expression for the following reaction.
200
Set up the equilibrium expression including activity coefficients for the following reaction:
PbBr2 (s) ----> Pb2+ (aq) + Br- (aq)
Ksp = { [Pb2+](γ pb2+)[Br-]2(γ Br-)2 }
200
What is the approximate pH of an aqueous solution containing 1.00 x 10-8 M NaOH? (No calculation needed)
pH = 7.00
300
What is ppm equivalent to? What is ppb equivalent to?
ppm = mg/L
ppb = microgram/L
300
Solve the following with the correct number of sig figs
(11.12-9.2) / (4.55 x 2.15) = ?
0.20 2 sig figs
300
Given the following reaction, which way would the equilibrium shift if the volume of the container is decreased?
The rxn shifts right as increasing pressure (same as decreasing volume) favors side with less moles of gas.
300
Write the charge balance for the equation for an aqueous solution of Fe2(SO4)3 if the species in solution include Fe3+, Fe(OH)2+, Fe(OH)2+, FeSO4+, SO42-, and HSO4-
[H+] + [FeSO4+] + 2[Fe(OH)2+] + [Fe(OH)2+] + 3[Fe3+] = [OH-] + 2[SO42-] + [HSO4-]
300
If NaF is added to an aqueous solution, will the solution be acidic, basic, or neutral?
Basic
400
A sample of waste water was found to have 34.0 ppm lead. What is the molarity of lead in this water sample? (H2O density = 1.000 g/mL, molecular weight of Pb2+ = 207.2 g/mol)
[Pb2+] = 1.64 x 10-4
400
What is the difference between accuracy and precision?
Accuracy = How close to true value
Precision = The reproducibility of a result
400
Calculate K for the overall reaction:
A + B ------> C K1 = 0.25
E -----> 2C + D K2 = 2.5
overall rxn: 2A + 2B + D -----> E K3 = ?
K3 = (1/K2) x (K1)2
K3 = (1/2.5) x (0.25)2
K3 = 0.025
400
What is the pH of an aqueous solution if the ionic strength equals 0.0100 and [H+] = 0.0200 M. (H+ radius = 900 pm)
activity coefficient for H+ = 0.913
-log(0.0200 x 0.913) = pH = 1.738
400
What is the pH of a solution when 0.450 M NaF is dissolved in solution? Ka = 7.2 x 10-4
pH = 8.40