# Take This pH Level Test Of Chemical Solutions!

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PH is a quantitative measure of the acidity which is measured with a pH meter for chemical solutions and widely used in chemistry, biology, and agronomy. S. P. L. Sørensen, a Danish biochemist, introduced the concept of pH, for measuring acidity and alkalinity. This quiz had been designed to test your knowledge about the pH level and effects of the solution. Read the questions carefully and answer. So, let's try out the quiz. All the best!

• 1.

### Calculate the hydroxide ion concentration of a solution if its pH is 6.389

• A.

1.00 x 10 -14 mol/L

• B.

4.08 x 10 -7 mol/L

• C.

2.45 x 10 -8 mol/L

• D.

9.92 x 10 -7 mol/L

C. 2.45 x 10 -8 mol/L
Explanation
The hydroxide ion concentration of a solution can be calculated using the formula pOH = 14 - pH. In this case, the given pH is 6.389. Subtracting this value from 14 gives us the pOH, which is 7.611. To find the hydroxide ion concentration, we can use the formula [OH-] = 10^(-pOH). Plugging in the value of pOH, we get [OH-] = 2.45 x 10^(-8) mol/L.

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• 2.

### What is the hydronium ion concentration in a solution with a pH of 2.80?

• A.

6.3 x 10 -2 mol/L

• B.

6.3 x 10 2nd power mol/L

• C.

4.8 x 10 -8 mol/L

• D.

1.6 x 10 -3 mol/L

D. 1.6 x 10 -3 mol/L
Explanation
The pH of a solution is a measure of its acidity. It is defined as the negative logarithm of the concentration of hydronium ions (H3O+). In this case, the pH is 2.80, which means the concentration of hydronium ions is 10^-2.80 mol/L. Therefore, the correct answer is 1.6 x 10^-3 mol/L.

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• 3.

### Consider the reaction of the base, ammonia (NH3), with water. The conjugate acid of NH3 is?

• A.

NH4+

• B.

H3O+

• C.

NH2-

• D.

OH-

A. NH4+
Explanation
When ammonia (NH3) reacts with water, it accepts a proton (H+) from water to form its conjugate acid. This results in the formation of the ammonium ion (NH4+). Therefore, NH4+ is the conjugate acid of NH3.

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• 4.

### Which of the following is not a strong acid in water?

• A.

HF

• B.

HCl

• C.

HBr

• D.

HNO3

A. HF
Explanation
HF is not a strong acid in water because it does not ionize completely. It only partially dissociates into H+ and F- ions in water. Strong acids, on the other hand, completely dissociate into ions when dissolved in water. Therefore, HF is not considered a strong acid.

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• 5.

### Which of the following substances when dissolved in water will form an acid aqueous solution?

• A.

KI

• B.

CH3COONa

• C.

Ba(OH)2

• D.

NH4Cl

D. NH4Cl
Explanation
NH4Cl will form an acid aqueous solution when dissolved in water. NH4Cl is the salt of a weak base (NH3) and a strong acid (HCl). When it dissolves in water, NH4Cl dissociates into NH4+ and Cl- ions. The NH4+ ion can act as a weak acid, donating a proton (H+) to water molecules, resulting in the formation of H3O+ ions. Therefore, the solution will have an excess of H3O+ ions, making it acidic.

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• 6.

### What is the pH of a 675 mL aqueous solution containing 0.036 mol of NaOH?

• A.

1.27

• B.

3.41

• C.

10.58

• D.

12.73

D. 12.73
Explanation
The pH of a solution can be determined by taking the negative logarithm of the concentration of hydrogen ions (H+). In this case, we have a solution of NaOH, which is a strong base that dissociates completely in water to produce hydroxide ions (OH-). Since NaOH is a strong base, it will completely react with water to form Na+ and OH- ions. Therefore, the concentration of OH- ions in the solution is equal to the concentration of NaOH. By using the formula for pH, which is pH = -log[H+], we can calculate the pH of the solution. In this case, the concentration of OH- ions is 0.036 mol, so the pH is -log(0.036) = 12.73.

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• 7.

### Or which one of the following reactions is the equilibrium constant Kc >1?

• A.

CH3COOH+H2O--CH3COO+H3O+

• B.

CH3COOH +OH--CH3COO +H2O

• C.

NH4+ +H2--NH3 +H2O+

• D.

Cl- +H2O--HCl +OH-

B. CH3COOH +OH--CH3COO +H2O
Explanation
In the reaction CH3COOH + OH- --> CH3COO- + H2O, the presence of OH- indicates the presence of a strong base. Strong bases completely dissociate in water, meaning that the reaction will favor the formation of products (CH3COO- and H2O) rather than reactants (CH3COOH and OH-). This results in a high concentration of products compared to reactants, leading to a Kc value greater than 1.

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• 8.

### Which, if any, of the following is an example of the leveling effect?

• A.

The concentrations of H+ and OH- in pure water are equal

• B.

The number of strong acids equals the number of strong bases

• C.

The number of strong acids equals the number of weak acids

• D.

In water, no acid stronger than H3O+ can exist

D. In water, no acid stronger than H3O+ can exist
Explanation
The leveling effect refers to the phenomenon in which strong acids and strong bases are "leveled" to the same strength in a solvent. In this case, the answer "In water, no acid stronger than H3O+ can exist" is an example of the leveling effect because it states that in water, the strongest acid that can exist is H3O+. This implies that any stronger acid is leveled to the same strength as H3O+ in water.

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• 9.

### Which of the following is most likely to act as a Lewis acid?

• A.

NH3

• B.

BF3

• C.

F

• D.

H2O

B. BF3
Explanation
BF3 is most likely to act as a Lewis acid because it is a compound with an incomplete octet and can accept a pair of electrons from a Lewis base. BF3 has an empty p-orbital on the boron atom, which allows it to accept an electron pair from a Lewis base, making it a Lewis acid. NH3, F, and H2O do not have the ability to accept electron pairs and therefore are not Lewis acids.

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• 10.

### Identify the conjugate base of HCO3- in the following reaction: CO3 2- +HSO4 ---HCO3- +SO4 2-

• A.

HSO4-

• B.

CO3 2-

• C.

OH-

• D.

SO4 2-

B. CO3 2-
Explanation
In the given reaction, HCO3- acts as an acid and donates a proton to HSO4-. As a result, HCO3- loses a proton and forms its conjugate base, which is CO3 2-. Therefore, the conjugate base of HCO3- in the reaction is CO3 2-.

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• 11.

### Identify the conjugate acid of SO4 2- in the following reaction: CO3 2- +HSO4- ----HCO3- +SO4 2-

• A.

CO3 2-

• B.

OH-

• C.

HSO4-

• D.

H3O+

C. HSO4-
Explanation
In the given reaction, CO3 2- acts as a base and accepts a proton (H+) from HSO4- to form HCO3-. Therefore, HSO4- is the conjugate acid of SO4 2- in this reaction.

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• 12.

### The OH- concentration in 1.0 x 10 -3 M Ba(OH)2 is:

• A.

2.00 x 10 -3 M

• B.

0.50 x 10 -3M

• C.

1.00 x 10 -3 M

• D.

1.00 x 10 -2 M

A. 2.00 x 10 -3 M
Explanation
The OH- concentration in 1.0 x 10 -3 M Ba(OH)2 is 2.00 x 10 -3 M because for every mole of Ba(OH)2 that dissolves, it produces two moles of OH-. Since the concentration of Ba(OH)2 is 1.0 x 10 -3 M, the concentration of OH- will be twice that, resulting in 2.00 x 10 -3 M.

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• 13.

### A 0.10 M NH3, solution is 1.3% ionized. Calculate the H+ ion concentration. NH3+H2O--NH4+ +OH-

• A.

1.3 x 10 -3 M

• B.

7.7 x 10 -12 M

• C.

7.7 x 10 -14 M

• D.

0.13 M

B. 7.7 x 10 -12 M
Explanation
The H+ ion concentration can be calculated using the equation for ionization of NH3 in water. Since NH3 is a weak base, it partially ionizes to form NH4+ and OH- ions. The concentration of NH3 that ionizes can be calculated by multiplying the initial concentration of NH3 (0.10 M) by the percent ionization (1.3% = 0.013). This gives a concentration of 0.0013 M for NH4+ and OH- ions. Since NH4+ and OH- ions are produced in equal amounts, the concentration of H+ ions can be considered the same as the concentration of OH- ions. Therefore, the H+ ion concentration is 0.0013 M, which is equivalent to 7.7 x 10-12 M.

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• 14.

### The pH of coffee is approximately 5.0. How many times greater is the [H3O+] in coffee than in tap water with a pH of 8.0?

• A.

0.62

• B.

30

• C.

1.6

• D.

1000

D. 1000
Explanation
The pH scale is a logarithmic scale that measures the concentration of hydrogen ions (H3O+) in a solution. A lower pH value indicates a higher concentration of hydrogen ions. In this question, coffee has a pH of 5.0, which means it has a higher concentration of hydrogen ions compared to tap water with a pH of 8.0. The difference in pH between the two solutions is 3.0 (8.0 - 5.0). Since the pH scale is logarithmic, each unit change in pH represents a tenfold difference in hydrogen ion concentration. Therefore, the [H3O+] in coffee is 1000 times greater than in tap water.

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• 15.

### Acid strength increases in the series HCN

• A.

H2SO4

• B.

SO4 2-

• C.

F-

• D.

CN-

D. CN-
Explanation
The given series represents different acids and their respective conjugate bases. In this series, CN- is the strongest acid because it has the most stable conjugate base, which is CN-. H2SO4 is a strong acid but its conjugate base, SO4 2-, is not as stable as CN-. F- is a weak acid and its conjugate base, F-, is even less stable. Therefore, the acid strength increases in the series HCN, H2SO4, F-, CN-.

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• 16.

### Which one of the following equations represents the reaction of a strong acid with a strong base?

• A.

H+(aq) + OH-===H2O(aq)

• B.

H+(aq)+CH3NH2(aq)--CH3NH3+(aq)

• C.

OH(aq)+HCN(aq)--H2O(aq)+CN-(aq)

• D.

HCN(aq)+CH3NH2(aq)--CH3NH3+(aq)+CN-(aq)

A. H+(aq) + OH-===H2O(aq)
Explanation
The equation H+(aq) + OH- === H2O(aq) represents the reaction of a strong acid with a strong base. In this equation, the hydrogen ion (H+) from the acid combines with the hydroxide ion (OH-) from the base to form water (H2O). This reaction is characteristic of a neutralization reaction between a strong acid and a strong base, where the resulting product is a neutral substance.

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• 17.

### Predict the direction in which the equilibrium will lie for the followijng reaction. C5H5COO- +HF--C6H5COOH +F

• A.

To the right

• B.

To the left

• C.

In the middle

A. To the right
Explanation
The reaction involves the transfer of a proton from HF to C5H5COO-. This proton transfer will favor the formation of C6H5COOH and F-. Since the reactants are on the left side of the equation and the products are on the right side, the equilibrium will lie to the right.

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• 18.

### Hard water deposits (calcium carbonate)have built up around your bathroom sink. Which one of the following would be best to dissolve the deposit?

• A.

Ammonia

• B.

Lye

• C.

Bleach

• D.

Vinegar

D. Vinegar
Explanation
Vinegar is the best option to dissolve the hard water deposits (calcium carbonate) around the bathroom sink. Vinegar contains acetic acid, which is a weak acid. When it comes into contact with calcium carbonate, it reacts and forms calcium acetate, carbon dioxide, and water. This reaction helps to break down and dissolve the deposits, making it easier to clean the sink. Ammonia, lye, and bleach are not as effective in dissolving calcium carbonate deposits.

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• 19.

### If a weak acid HA has Ka=10-5, what is the pH of a mixture of 0.1 mole of the acid and 0.1 mole of its conjugate based in 1.0 liter of water?

• A.

3

• B.

4

• C.

5

• D.

9

C. 5
Explanation
The pH of a solution can be determined by the concentration of hydrogen ions (H+). In this case, the weak acid HA is partially dissociated in water, forming H+ ions. The Ka value of 10^-5 indicates that the acid is not very strong, meaning that only a small fraction of it will dissociate. When the acid and its conjugate are mixed together, they will react to form a buffer solution. A buffer solution resists changes in pH when small amounts of acid or base are added. The pH of a buffer solution is determined by the pKa value of the acid. Since the Ka value is 10^-5, the pKa value will be 5. Therefore, the pH of the mixture will also be 5.

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• 20.

### What is the solubility product constant expression (Ksp) for PbCl2?

• A.

[Pb2+](2)[Cl]

• B.

[Pb2+][Cl-]/2

• C.

[Pb2+][Cl-]2

• D.

[Pb2+][Cl-]/[[PbCl2]

C. [Pb2+][Cl-]2
Explanation
The solubility product constant expression (Ksp) for PbCl2 is given by [Pb2+][Cl-]2. This expression represents the equilibrium constant for the dissolution of PbCl2 in water, where [Pb2+] represents the concentration of lead ions and [Cl-] represents the concentration of chloride ions. Since there are two chloride ions for every lead ion in the formula unit of PbCl2, the concentration of chloride ions is squared in the Ksp expression.

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• 21.

### Which one of the following salts would form an acidic solution when dissolved in water.

• A.

NaBr

• B.

NaF

• C.

NaHSO4

• D.

CaCl2

C. NaHSO4
Explanation
NaHSO4 is the correct answer because it is a salt of a strong acid (H2SO4) and a weak base (NaOH). When NaHSO4 is dissolved in water, it dissociates into Na+ and HSO4- ions. The HSO4- ion can act as a weak acid, releasing H+ ions into the solution, resulting in an acidic pH.

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• 22.

### Calculate the pH of a solution that is 0.410 M in HOCl and 0.050M in NaOCl. Ka(HOCl)=3.0 x 10 -8

• A.

6.58

• B.

0.39

• C.

3.94

• D.

7.49

A. 6.58
Explanation
The pH of a solution can be calculated using the equation pH = -log[H+]. In this case, the solution contains HOCl, which is a weak acid. The concentration of H+ ions can be determined by calculating the concentration of the dissociated form of the acid, which is given by the equation [H+] = âˆš(Ka x [HOCl]). Plugging in the given values, [H+] = âˆš(3.0 x 10^-8 x 0.410) = 6.58 x 10^-5 M. Taking the negative logarithm of this concentration gives the pH value of 6.58.

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• 23.

### What is the pH at the equilvalence point in the titration of 100 mL of 0.10M HCl with 0.10M NaOH?

• A.

1.0

• B.

6.0

• C.

7.0

• D.

13.0

C. 7.0
Explanation
At the equivalence point in a titration, the moles of acid and base are equal. In this case, 100 mL of 0.10M HCl is being titrated with 0.10M NaOH. Since the concentration of the acid and base are the same, the pH at the equivalence point will be neutral, which is 7.0.

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• 24.

### Which of these salts has the smallest molar solubility? Solid Ksp _________________________ CdS 3.6 x 10 -29 AgCl 2.0 x 10 -13 Ni(OH)2 2.8 x 10 -16 AgI 1.5 x 10 -16 PbS 8.4 x 10 -28

• A.

CdS

• B.

Ni(OH)2

• C.

AgCl

• D.

AgI

A. CdS
Explanation
CdS has the smallest molar solubility because it has the lowest value for its solubility product constant (Ksp) compared to the other salts. The solubility product constant is a measure of the extent to which a salt dissolves in water. A lower value of Ksp indicates lower solubility, meaning that CdS has a smaller molar solubility compared to the other salts listed.

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• 25.

### What is the pH of a 0.20 M CH3COOH (acetic acid) solution? (Ka=1.8 x 10 -5)

• A.

X=[H+]=1.9x 10 -3--pH=-log{H+]=2.7

• B.

PH=107

• C.

PH=1.0

A. X=[H+]=1.9x 10 -3--pH=-log{H+]=2.7
Explanation
The pH of a solution can be calculated using the concentration of hydrogen ions ([H+]). In this case, the concentration of [H+] is determined to be 1.9x10^-3. The pH is then calculated by taking the negative logarithm of the [H+] concentration, resulting in a pH value of 2.7.

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• 26.

### What is the pH of a solution prepared from 0.250 mol of NH3 dissolved in sufficient water to make 1.00 L of solution? (Kb=1.8 x 10 -5)

• A.

[OH-]=x=2.1 x 10 -3 --pOH=2.67==PH=11.3

• B.

PH=6.6

• C.

PH=5.2

A. [OH-]=x=2.1 x 10 -3 --pOH=2.67==PH=11.3
Explanation
The correct answer is [OH-]=x=2.1 x 10 -3 --pOH=2.67==PH=11.3. This is because the given solution is prepared from NH3, which is a weak base. When NH3 is dissolved in water, it reacts with water to form NH4+ and OH-. The concentration of OH- can be determined using the Kb value for NH3. From the concentration of OH-, we can calculate the pOH using the equation pOH = -log[OH-]. Finally, the pH can be calculated by subtracting the pOH from 14, as pH + pOH = 14. Therefore, the pH of the solution is 11.3.

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• 27.

### A buffer is prepared by mixing 100 mL of 0.500 M HCl and 200 mL of 0.500 M sodium acetate. The Ka for acetic acid is 1.8 x 10 -5. Calculate the pH of the buffer.

• A.

4.74 + log 50/300/50/300=4.74 pH=pKa

• B.

PH=42

• C.

PH=3.2

A. 4.74 + log 50/300/50/300=4.74 pH=pKa
Explanation
The correct answer is 4.74. The pH of a buffer can be calculated using the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]). In this case, the pKa is given as 4.74, and the ratio [A-]/[HA] can be calculated as (50/300)/(50/300) = 1. Substituting these values into the Henderson-Hasselbalch equation gives pH = 4.74 + log(1) = 4.74.

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• 28.

### Calculate the solubility of calcium phosphate in a saturated solution. (Ksp for Ca3(PO4)2=1.3 x 10 -26

• A.

2.6 x 10 -6 M

• B.

3.6 x 10 -6 M

• C.

16.0 x 10 -6 M

A. 2.6 x 10 -6 M
Explanation
The solubility of calcium phosphate in a saturated solution is 2.6 x 10 -6 M. This value is determined by the equilibrium constant, Ksp, for Ca3(PO4)2, which is given as 1.3 x 10 -26. The Ksp expression for calcium phosphate is [Ca2+][PO4 3-]^2. By setting up an ICE table and using the Ksp expression, we can calculate the solubility of calcium phosphate. The solubility is the concentration of calcium ions (Ca2+) in the saturated solution, and it is equal to 2.6 x 10 -6 M.

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• Mar 20, 2022
Quiz Edited by
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