The Strength Test
Inseparable Pairs
Weak and Feeble
"Neutralize" the Target (Beginner Level)
Mom, the computer's Buffering...
100
Name any 4 Strong Acids
Possible Answers include any 4 of the following: H2SO4, HI, HCl, HBr, HClO4, HNO3
100
If an acid is strong, then the direction of equilibrium will be towards ____ ?
RIGHT
100
Which of the following statement(s) is/are true for a weak acid
a. Has a strong conjugate base
b. Disassociated to a small extent in aq solutions
c. Ka value is large
a and b
100
How many mL of a 0.20 M KOH solution will exactly neutralize 15.0 mL of 0.40 M HCL?
x = 30 mL
100
Name the following equation:
pH = pKa + log( [A-] / [HA] )
Henderson-Hasselbalch Equation
200
Define the "strength" of an acid or base.
The strength of an acid or base refers to its ease in dissociating into its conjugate and H+ or OH- respectively.
200
The conjugate base of HSO4- is
a. H2SO4
b. SO42-
c. H3SO4+
d. HSO4+
e. OH-
b. SO42-
200
True or False: Water is an amphoteric substance. This means that it can turn into an acid-base hybrid in solution.
False
200
Calculate the volume of 0.250 M NaOH solution required to neutralize 50.0 mL of 0.150 M HCl.
30.0 mL
200
You have a buffer solution that contains 0.300 M acetic acid (CH₃COOH) and 0.300 M sodium acetate (CH₃COONa). Calculate the pH of this buffer solution. (Ka = 1.8 x 10-5)
pH = 4.74
300
The stronger the acid,
a. the stronger its conjugate base
b. the weaker its conjugate base
c. the more concentrated the acid.
d. the less concentrated the conjugate base
e. the more concentrated the conjugate base.
b. the weaker its conjugate base
300
Which of the following is the conjugate acid of H2PO4-?
a. H3O+
b. PO43-
c. HPO42-
d. H3PO4
d. H3PO4
300
Calculate the pH of a 50mL solution of 0.235M HC2H3O2. (Ka = 1.8 x 10-5)
pH = 2.69 (Do not accept unrounded values like 2.6868)
300
How many grams of Ca(OH)2 are needed to completely neutralize 75.0 mL of 0.400 M HCl?
1.111g Ca(OH)2
300
A student prepares a buffer by combining samples of HCN (a1) and NaCN (aq) . A particle view of the buffer solution is shown below. Water molecules and cations are not depicted.
Which of the following is true about the pH of the buffer? (The pKa HCN is 9.21)
a. pH < 9.21
b. pH = 9.21
c. pH > 9.21
d. relative pH cannot be determined w/ additional information
c. pH > 9.21
400
Each of the following pairs contains one strong acid and one weak acid EXCEPT:
a. H2SO4 and H2CO3
b. HNO3 and HNO2
c. HBr and H3PO2
d. HSO4- and HCN
e. HCl and H2S
d. HSO4- and HCN
400
Identify the acid, base, conjugate acid, and conjugate base for the following:
HClO4(aq) + H2O(l) ⇌ H3O+(aq) + ClO4-(aq)
HClO4(aq) = acid
H2O(l) = base
H3O+(aq) = conjug. acid
ClO4-(aq) = conjug. base
400
The pH of an aqueous sodium fluoride (NaF) solution is __________ because __________
a. 7; sodium fluoride is a simple salt.
b. above 7; fluoride is a weak base.
c. below 7; fluoride reacts with water to make hydrofluoric acid.
d. about 7; fluoride is a weak base, but produces hydrofluoric acid, and these two neutralize one another.
e. 0; sodium fluoride is a salt not an acid or a base.
b. above 7; fluoride is a weak base.
400
Determine the pH of the solution after 25.0 mL of 0.150 M HNO3 is added to 50.0 mL of 0.200 M NaOH.
(4 significant figures ONLY)
pH = 12.92
400
Determine final pH when 0.0100 moles of HCl is added to a 500.0 mL buffer solution containing 0.200 M HCOOH and 0.200 M HCOONa. (Ka = 1.8 x 10-5)
pH = 3.65
500
Use the following acid ionization constants to identify the correct decreasing order of base strengths.
HF Ka = 7.2 × 10-4
HNO2 Ka = 4.5 × 10-4
HCN Ka = 6.2 × 10-10
a. CN- > NO2- > F-
b. NO2- > F- > CN-
c. F- > CN- > NO2-
d. F- > NO2- > CN-
e. NO2- > CN-> F-
a. CN- > NO2- > F-
500
Identify the acid, base, conjugate acid, and conjugate base for the following:
H2S(g) + H2O(l) ⇌ H3O+(aq) + HS-(aq)
H2S(g) = acid
H2O(l) = base
H3O+(aq) = conjug. acid
HS-(aq) = conjug. base
500
True or False: Acids and Bases can be weaker than water. (Include conjugate acids and conjugate bases in this classification of acids and bases)
True
500
You have 100.0 mL of a solution containing 0.100 M HCl and 0.050 M H2SO4. Calculate the pH of the solution after the addition of 80.0 mL of 0.250M KOH
(Answer to 4 significant figures)
pH = 12.40
500
Calculate the pH of a buffer solution prepared by mixing 100.0 mL of 0.150 M benzoic acid (C₆H₅COOH) with 100.0 mL of 0.200 M sodium benzoate (C₆H₅COONa). (Ka = 6.3 x 10-5)
pH = 4.33