Acids
Bases
pH Scale
Titrations
100
What is the conjugate base of water when water acts as an acid?
OH-
100
What is the conjugate acid of water when water acts as an base?
H3O+
100
The pH of a solution changes from 8 to 9.
A. the concentration of OH- decreases by 1 mole/L
B. the concentration of OH- decreases by 10 mol/L
C. the concentration of OH- increases by 1 mole/L
D. the concentration of OH- increased by 10 mole/L
D
The pH of a solution changes from 8 to 9.
The pH scale is logarithmic. every increase is a 10x change in concentration
8 --> 9 is getting more basic. [OH-] INCREASED
100
Describe the color of phenolphthalein in different conditions.
Acidic - clear
Basic - prettiest pink around
200
What is both the Bronsted-Lowry Definition and Arrhnius definition of an acid?
Proton donor
or
Releases H+ ions into solution
200
What is the Arrhenius definition of a base?
What is the Bronsted Lowry definition of a base?
Can't remember which one is which? Say them both at least.
A: Releases OH- ions
BL: H+ acceptor; takes H+ out of solution
200
What is the concentration of H+ is in a solution that has a pH of 9.4?
UNITS ON YOUR ANSWER
3.98 x 10-10 M or mol H+/L
[H+] = 10-pH
200
WHY did we stop titrations at a pale pink color? Describe what is happening at the molecular level at that exact point in time.
At the equivalence point.
H+ ions equal to OH- ions; pH 7
300
Which side of the pH scale is the acidic side?
Give a number range.
Less than 7.
0-7
300
What side of the pH scale is basic? Give a range.
More than 7.
7-14
300
2HCl + Ca(OH)2 --> H2O + CaCl2
When HCl is titrated with Ca(OH)2, it releases 0.034 moles of H+ ions. How many moles of OH- ions are in the solution when it turns pale pink?
0.034 moles of OH- ions
400
You have 50 mL of HCl at a pH of 5.
You dilute it with 100 mL of water.
What is the pH of your new diluted solution?
(challenge problem, not on test)
1) how much H+ did you start with?
[H+] = 10-5 = 1x10-5 mol H+/L
1x10-5 mol H+/L * 0.05 L = 5*10-7 mol H+
2) We diluted the solution with 100mL, so the new solution has a total volume of 150 mL, or 0.15L
3) find new [H+]. Take moles H+, divide by L solution [H+] = 5*10-7 / 0.15L = 3.33*10-6 M
4) Find pH pH = -log[H+] = -log[3.33*10-6 M]
pH = 5.48
400
What is the molarity of a KOH solution if 25 mL of it is neutralized by 31.7 mL of a 0.1 M HNO3 solution?
KOH + HNO3 --> KNO3 + H2O
0.13 M
500
Identify the acid/base/conjugate acid/conjugate base
HPO42- + H2O <--> H2PO4- + OH-
Acid: H2O Conjugate Base: OH-
Base: HPO42- Conjugate Acid: H2PO4-
500
Identify the acid/base/conjugate acid/conjugate base
H3PO4 + NH3 <--> NH4+ + H2PO4-
Acid: H3PO4 Conjugate Base: H2PO4-
Base: NH3 Conjugate Acid: NH4+
500
What does the pH scale actually measure?
How much H+ is in a solution.
[H+]
500
H2SO4 + 2KOH --> 2H2O + K2SO4
A 25mL sample of H2SO4 is neutralized by 27.4 mL of 1.3M KOH. What is the concentration of the acid?
0.71 M
