Answers2026-2027_MDCPS_2003345_Chemistry_1_B-CRLab: Measuring pH

Lab: Measuring pH — Unit test Answers

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A solution of ammonia has a pH of 11.8. What is the concentration of OH– ions in the solution?Useful formulas include , , , and .

Question illustration
A
1.58 10–12 M
Option A
B
6.31 10–3 M
Option B
C
2.20 M
D
158 M
2
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Which description correctly characterizes the acidity or basicity of a solution?

A
The higher the pH is, the more the hydroxide ion concentration decreases and the more acidic the solution becomes.
B
The higher the pH is, the more the hydroxide ion concentration increases and the more basic the solution becomes.
C
The lower the pH is, the more the hydronium ion concentration decreases and the more acidic the solution becomes.
D
The lower the pH is, the more the hydronium ion concentration increases and the more basic the solution becomes.
3

Soaps feel slippery on our hands because they dissolve the oil on our skin, decreasing friction.This is because soap contains

A
a neutral molecule.
B
a salt molecule.
C
an acid.
D
a base.
4

Which pair of substances would most likely result in the production of a gas when reacting with an acid?

A
litmus and methyl orange
B
base and salt
C
metal and carbonate
D
carbon dioxide and water
5

Lewis acids and bases are most closely associated with which process?

A
proton transfer
B
electron transfer
C
the formation of aqueous ions
D
the formation of a conjugate acid or base
6

Consider the reaction below.NH4+ + H2O NH3 + H3O+Which is an acid-conjugate base pair?

Question illustration
A
NH4+ and NH3
B
NH4+ and H3O+
C
H2O and NH3
D
H2O and H3O+
7

A number of beakers have different concentrations of a solution. Which statement best describes the most concentrated solution?

A
It has the largest volume.
B
It has the most solute for a given volume.
C
It has the greatest amount of solute.
D
It has the most volume for a given amount of solute.
8

In a coffee shop, the following coffee samples are prepared for customers.i. 10 g of sugar added to 100 g of coffeeii. 10 g of sugar added to 200 g of coffeeiii. 4 g of sugar added to 200 g of coffeeiv. 4 g of sugar added to 100 g of coffeeBased on the amount of sugar added, which sequence ranks the coffee from the sweetest coffee to the least-sweet coffee?

A
i, ii , iii, iv
B
iii, iv, ii, i
C
iv, i, ii, iii
D
i, ii, iv, iii
9

Which of these correctly defines the pOH of a solution?

A
the log of the hydronium ion concentration
B
the negative log of the hydronium ion concentration
C
the log of the hydroxide ion concentration
D
the negative log of the hydroxide ion concentration
10

What type of substance reacts with limestone (CaCO3) and produces carbon dioxide gas?

A
a neutral substance
B
a base
C
an acid
D
both an acid and a base
11

Which of the following substances is an Arrhenius acid?

A
BF3
B
HCN
C
NH3
D
Mg(OH)2
12

Given that the molar mass of NaCl is 58.44 g/mol, what is the molarity of a solution that contains 87.75 g of NaCl in 500. mL of solution?Use .

Question illustration
A
0.333 M
B
0.751 M
C
1.50 M
D
3.00 M
13

A 1.00 L volume of HCl reacted completely with 2.00 L of 1.50 M Ca(OH)2 according to the balanced chemical equation below.2HCl + Ca(OH)2 CaCl2 + 2H2OWhat was the molarity of the HCl solution?

Question illustration
A
0.375 M
B
1.50 M
C
3.00 M
D
6.00 M
14

An unknown substance turns blue litmus paper to red. Which additional test could be used to confirm the substance’s identity?

A
It should turn phenolphthalein from colorless to pink because it is a base.
B
It should turn phenolphthalein from pink to colorless because it is a base.
C
It should turn methyl orange to orange because it is an acid.
D
It should turn methyl orange to red because it is an acid.
15

A solution of HCl has = 0.01 M. What is the pH of this solution?Use .

Question illustration
A
–2
B
–1
C
1
D
2
16

What is the definition of a Lewis base?

A
a substance that donates a proton
B
a substance that donates electrons to form a covalent bond
C
a substance that accepts electrons to form a covalent bond
D
a substance that when dissolved in water increases hydrogen ion concentration
17

Which best describes the definition of Lewis acids and bases?

A
a general definition based on electron structure
B
a general definition based on hydrogen ion concentration
C
a specific definition based on a compound’s ability to accept protons
D
a specific definition based on a compound’s ability to donate protons
18

Which solution is the most concentrated?

A
2.0 mL of 10 M H2SO4, where H2SO4 has a molar mass of 98 g/mol
B
5.0 mL of 1.0 M PbSO4, where PbSO4 has a molar mass of 303 g/mol
C
2.0 mL of 10.5 M H2O2, where H2O2 has a molar mass of 34 g/mol
D
100 mL of 10 M NaCl, where NaCl has a molar mass of 58 g/mol
19

Which describes an alkaline solution?

A
pH less than 7
B
pH equal to 7
C
basic
D
acidic
20

What is the Bronsted-Lowry definition of a base?

A
a compound that donates protons
B
a compound that accepts protons
C
a substance that increases hydroxide ion concentration
D
a substance that increases hydronium ion concentration

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