# Worksheet: The pH Scale

In this worksheet, we will practice defining pH as a logarithmic measure of acid concentration and using it to determine the relative acidity or basicity of a substance.

Q1:

Coffee has a pH of 5. Is it acidic, basic, or neutral?

• ANeutral
• BBasic
• CAcidic

Q2:

Ocean water has a pH of 8. Is it acidic, basic, or neutral?

• ANeutral
• BAcidic
• CBasic

Q3:

Milk of magnesia has a pOH of 3.5. Is it acidic, basic, or neutral?

• ABasic
• BAcidic
• CNeutral

Q4:

Orange juice has a pOH of 9.8. Is it acidic, basic, or neutral?

• ANeutral
• BBasic
• CAcidic

Q5:

In which range of values would the pH of a basic solution be found?

• A>5
• B>10
• C>7
• D<7
• E<10

Q6:

Is a solution of pH 6.9 acidic, basic, or neutral?

• AAcidic
• BBasic
• CNeutral

Q7:

In which range of values would the pH of an acidic solution be found?

• A<7
• B>5
• C<5
• D>7
• E<10

Q8:

Is a solution of pH 3.2 acidic, basic, or neutral?

• ABasic
• BNeutral
• CAcidic

Q9:

What is the pH of a neutral solution at room temperature?

Q10:

Calcium carbonate will produce a fizz of carbon dioxide when added to lemon juice. Based on this observation, what can be said about the pH of lemon juice?

• A<10
• B>5
• C>7
• D<7
• E<5

Q11:

Which of the following pH values would a solution of lemon juice most likely have?

• A2.5
• B7.5
• C0.0
• D10.0
• E5.0

Q12:

How can an indicator be used to estimate the pH of a solution?

• AAn indicator will turn from a solid to a liquid in basic solutions.
• BAn indicator will make a “squeaky pop” noise in acidic solutions.
• CAn indicator will change color above or below a specific pH range.
• DAn indicator can measure the exact concentration of ions in an aqueous solution.
• EAn indicator will give off a different gas depending on whether a solution is acidic or basic.

Q13:

Fill in the blank: pH is a measurement of the concentration, in an aqueous solution, of .

• A molecules
• B ions
• Celectrons
• D atoms
• E ions

Q14:

A few drops of universal indicator were added to four flasks containing unknown solutions. Which of the following values provide the best estimate for the pH of each solution? • AA = 11, B = 1, C = 5, and D = 7
• BA = 5, B = 7, C = 11, and D = 1
• CA = 5, B = 1, C = 11, and D = 7
• DA = 1, B = 11, C = 7, and D = 5
• EA = 7, B = 11, C = 5, and D = 1

Q15:

In an experiment, a solution of 1 M was placed into a beaker. Powdered was added to the beaker at regular intervals and the pH was continually measured. Which of the graphs shows how the pH would change during this experiment?

• A • B • C • D Q16:

The table below shows the relationship between pH and the concentration of ions in an aqueous solution. What is the value of ?

 Concentration of H+ ions/mol⋅dm−3 0.1 0.01 𝑥 0.0001 1e-05 pH 1 2 3 4 5
• A0.0001
• B0.1
• C0.001
• D0.05
• E0.005

Q17:

Which of the following diagrams represents a correctly labeled pH scale?

• A • B • C • D Q18:

Which of the following descriptions explains how litmus paper can be used to test for acids?

• AAcids turn blue litmus paper red.
• BAcids keep blue litmus paper blue.
• CAcids turn red litmus paper blue.
• DAcids turn red litmus paper purple.
• EAcids turn blue litmus paper purple.

Q19:

An acidic solution was found to have a pH of 1. Upon the addition of a small volume of a base, the pH changed to 3. By what factor has the concentration of ions changed?

• AIncreased by a factor of 2
• BDecreased by a factor of 10
• CDecreased by a factor of 100
• DIncreased by a factor of 100
• EDecreased by a factor of 2

Q20:

Fill in the blanks: Litmus is a mixture of dyes extracted from lichen. It can be used to detect if solutions are acidic or basic. It is in acidic solutions and in basic solutions.

• Ared, blue
• Bcolorless, pink
• Cgreen, blue
• Dpink, colorless
• Eblue, red

Q21:

What is the key feature of a chemical that makes it useful as a pH indicator?

• AColor changes with varying pH
• BSolubility in water
• CLow molar mass
• DCheapness
• ELow reactivity

Q22:

Which of the following represents the colour of litmus paper in a neutral medium?

• ABlue
• BPurple
• CColourless
• DRed

Q23:

Which of the following statements about the relationship between and and the value of pH is correct?

• AIf the concentration of , the solution is basic and the value of pH is less than 7.
• BIf the concentration of , the solution is acidic and the value of pH is greater than 7.
• CIf the concentration of , the solution is acidic and the value of pH is less than 7.
• DIf the concentration of , the solution is basic and the value of pH is less than 7.