Ph Scale

Question 1

What does the pH scale measure

Answer 1

pH scale measures the acidity or alkalinity of a solution based on the concentration of hydrogen ions (H+)

Question 2

What’s the pH range of acidic solution

Answer 2

Less than 7

Question 3

What’s the pH of a neutral solution

Answer 3

pH 7

Question 4

What’s the pH range of an alkaline solution

Answer 4

Greater than 7

Question 5

What ion is present in all acidic solutions

Answer 5

Hydrogen ions (H+)

Question 6

What ion is present in all alkaline solutions?

Answer 6

Hydroxide ions (OH- )

Question 7

How does the concentration of H+ ions change with each pH unit?

Answer 7

Each pH unit change represents a tenfold change in H+ ion concentration

Question 8

General ructions for a neutralisation reaction

Answer 8

Acid+Base ____ Salt+Water

Question 9

Whats the product of reaction between hydrochloric acid and sodium hydroxide

Answer 9

Sodium chloride and water

Question 10

What’s the pH of the solution after a complete neutralisation reaction

Answer 10

pH 7

Question 11

Name 3 ways to measure a pH

Answer 11

Universal indicator, pH metres and litmus paper

Question 12

What colour does universal indicator turn in a strong acid

Answer 12

Red

Question 13

What’s the advantage of using a pH metre over an indicator

Answer 13

A pH metre provides a precise numerical value

Question 14

What’s the difference between strong ans weak acid

Answer 14

Strong acid fully ionize in water,while weak acids only partially ionize

Question 15

Which will have a lower pH: a strong or a weak acid of the same concentration

Answer 15

A strong acid

Question 16

Which solution has the highest concentration of H+ ions

Answer 16

pH 2

Question 17

A solution has a pH of 3. Is it acidic,neutral, or alkaline

Answer 17

Acidic

Question 18

A solution has a pH of 8. What type of solution is it

Answer 18

Weakly alkaline

Question 19

Describe how u could measure the pH of a solution in a laboratory

Answer 19

Use a universal indicator to observe the colour change or a pH probe to measure the numerical pH value.

Question 20

Describe how u could measure the pH of a solution in a laboratory

Answer 20

Use a universal indicator to observe the colour change or a pH probe to measure the numerical pH value.

Question 21

A student adds sodium hydroxide to hydrochloric acid, and the pH changes from 2 to 7. What type of reaction has occurd

Answer 21

Neutralisation

Question 22

Explain why strong acids have lower pH values than weak acids of the same concentration.

Answer 22

Strong acids fully ionize in water, releasing more H⁺ ions into the solution, which lowers the pH. Weak acids only partially ionize, so the concentration of H⁺ ions is lower, resulting in a higher pH.

Question 23

A student measures the pH of two solutions: hydrochloric acid (HCl) and ethanoic acid (CH₃COOH). Both have the same concentration. Explain why HCl has a lower pH

Answer 23

HCl is a strong acid and fully ionizes in solution, producing more H⁺ ions. Ethanoic acid is a weak acid and only partially ionizes, so it produces fewer H⁺ ions.

Question 24

A solution of pH 6 is diluted 10 times. What is the new pH?

Answer 24

The new pH is closer to 7, as dilution reduces the concentration of H⁺ ions.

Question 25

What does a pH of 7 indicate about a solution?

Answer 25

Neutral.

Question 26

he colors observed are red, green, and purple. State the approximate pH for each color and classify the solutions as acidic, neutral, or alkaline.

Answer 26

Red: pH 1 (acidic).

Green: pH 7 (neutral).

Purple: pH 13 (alkaline).