ANSWERS
pH and Life
Part 1 - Calculating pH.
Determine the pH of the following hydrogen ion concentrations using the formula
below. Then determine if the solution is an acid, base, or neutral.
pH = -log [H+]
Example [H+] = 1.0 X10-7= -log [1.0 X10-7]= 7.0 = neutral
1. [H+] = 2.5x10-6 = 5.59 = acid
5. [H+] = 0.000316 = 3.5 = acid
2. [H+] = 6.3x10-8 = 7.2 = neutral
6. [H+]= 1.58x10-7 = 6.8 = neutral
3. [H+] = 1.99x10-10 = 9.7 =base
4. [H+] = 3.16x10-11 = 10.5 =base
Part 2- Calculating hydrogen ion concentration.
Determine the hydrogen ion concentrations of the following pH using the formula
below.
inverse log -pH = [H+]
1. pH= 4.3 = [H+] = 5.0x10-5
5. pH=11= [H+] = 1.0x10-11
2. pH= 7.9= [H+] = 1.3x10-8
6. pH=7= [H+] = 0.0000001
3. pH= 2.6= [H+] = 0.0251
4. pH= 9.8= [H+] = 1.58x10-10
Part 3 – Pond pH
Given below are the pH ranges at which various aquatic organisms can survive.
Based on the given hydrogen ion concentrations, determine the pH of each pond.
Then use the information below to rank the ponds from best to worst for
supporting life and explain why.
pH Ranges that Support Aquatic Life: Below are the normal ranges for
various organism and the levels of pH they can live at.
Bacteria: 1.5 to 13.5
Plants: 6.5 to 12.0
Carp, suckers, catfish: 6.0 to 9.0
Bass, crappies: 6.5 to 8.5
Snails, clams, mussels: 7.5 to 9.0
Trout, frogs, aquatic invertebrates*: 6.5 to 7.5
(*most mayfly, stonefly, and caddisfly nymphs; tadpoles)
Little Bass: 2.0x10-9 M= 8.69 pH
Glacier: 5.6x10-8 M = 7.25 pH
Antler: 5.62x10-7 M = 6.25 pH
Big Bass 3.16 x10-10 M = 9.5 pH
Part 4 – Human Blood pH
The normal blood pH for a human is 7.35-7.45. This narrow range can be
affected when various organs are not functioning properly. When a person
cannot get rid of the CO2 from their lungs they may become acidotic (pH less
than 7.35). If however a person’s kidneys are overproducing sodium bicarbonate
they may become alkalotic [basic] (where the pH is greater than 7.45).
Blood was drawn on three patients in the hospital. Below are the concentrations
of hydrogen ions found in their blood stream. Determine for each person:
1. The pH of their blood
2. If they are normal, acidotic, or alkalotic (basic)
3. If they should see another doctor (namely a respiratory (lung) doctor or
renal (kidney) doctor
Patient
Mr. Nephros
Hydrogen Ion
Concentration
7.79 pH = 1.6x10-8
Miss Alveola
7.14 pH = 7.1x10-8
Mrs. Sanguine
7.38 pH = 4.1x10-8
pH
pH Term
Doctor?
pH and Life
Part 1 - Calculating pH.
Determine the pH of the following hydrogen ion concentrations using the formula
below. Then determine if the solution is an acid, base, or neutral.
pH = -log [H+]
Example [H+] = 1.0 X10-7= -log [1.0 X10-7]= 7.0 = neutral
1. [H+] = 2.5x10-6 =
5. [H+] = 0.000316 =
2. [H+] = 6.3x10-8 =
6. [H+]= 1.58x10-7 =
3. [H+] = 1.99x10-10 =
4. [H+] = 3.16x10-11 =
Part 2- Calculating hydrogen ion concentration.
Determine the hydrogen ion concentrations of the following pH using the formula
below.
inverse log -pH = [H+]
1. pH= 4.3 = [H+] =
5. pH=11= [H+] =
2. pH= 7.9= [H+] =
6. pH=7= [H+] =
3. pH= 2.6= [H+] =
4. pH= 9.8= [H+] =
Part 3 – Pond pH
Given below are the pH ranges at which various aquatic organisms can survive.
Based on the given hydrogen ion concentrations, determine the pH of each pond.
Then use the information below to rank the ponds from best to worst for
supporting life and explain why.
pH Ranges that Support Aquatic Life: Below are the normal ranges for
various organism and the levels of pH they can live at.
Bacteria: 1.5 to 13.5
Plants: 6.5 to 12.0
Carp, suckers, catfish: 6.0 to 9.0
Bass, crappies: 6.5 to 8.5
Snails, clams, mussels: 7.5 to 9.0
Trout, frogs, aquatic invertebrates*: 6.5 to 7.5
(*most mayfly, stonefly, and caddisfly nymphs; tadpoles)
Little Bass: 2.0x10-9 M=
Glacier: 5.6x10-8 M =
Antler: 5.62x10-7 M =
Big Bass 3.16 x10-10 M =
Part 4 – Human Blood pH
The normal blood pH for a human is 7.35-7.45. This narrow range can be
affected when various organs are not functioning properly. When a person
cannot get rid of the CO2 from their lungs they may become acidotic (pH less
than 7.35). If however a person’s kidneys are overproducing sodium bicarbonate
they may become alkalotic [basic] (where the pH is greater than 7.45).
Blood was drawn on three patients in the hospital. Below are the concentrations
of hydrogen ions found in their blood stream. Determine for each person:
1. The pH of their blood
2. If they are normal, acidotic, or alkalotic (basic)
3. If they should see another doctor (namely a respiratory (lung) doctor or
renal (kidney) doctor
Patient
Mr. Nephros
Hydrogen Ion
Concentration
1.6x10-8
Miss Alveola
7.1x10-8
Mrs. Sanguine
4.1x10-8
pH
pH Term
Doctor?