LESSON 2: pH scale

True – Acidic substances taste sour, while basic substances feel slippery.

T OR F

Acidic substances tend to taste sour, while basic substances feel slippery.

False – Neutral solutions have equal concentrations of hydronium and hydroxide ions.

T OR F

Neutral solutions have unequal concentrations of hydronium and hydroxide ions.

False – Acidic solutions have a higher concentration of hydronium ions than hydroxide ions.

T OR F

Acidic solutions have a higher concentration of hydroxide ions than hydronium ions.

True – The pH scale was proposed in 1909 by Søren Sørensen.

T OR F

The pH scale was proposed in 1909 by Danish biochemist Søren Sørensen

True – pH measures acidity and basicity (alkalinity) of a solution.

T OR F

pH is a measure of the acidity or basicity (alkalinity) of a solution

True – As pH decreases, [H+] increases.

T OR F

As pH decreases, the concentration of hydrogen ions ([H+]) increases.

False – pOH decreases when [OH-] increases.

T OR F

pOH decreases when the concentration of hydroxide ions ([OH-]) decreases.

True – The pH of a solution is calculated as the negative logarithm of [H+].

T OR F

The pH of a solution is calculated using the negative logarithm of [H+].

• False – The pOH of a solution is calculated using the negative logarithm of [OH-], not [H+].

T OR F

The pOH of a solution is calculated using the negative logarithm of [H+].

True – A pH meter provides more accurate pH measurements than pH paper.

T OR F

A pH meter provides more accurate pH measurements than pH paper.

b) Sour – Acidic substances taste sour.

What do acidic substances generally taste like?
a) Bitter
b) Sour
c) Sweet
d) Salty

c) Neutral – Neutral solutions have equal concentrations of H₃O⁺ and OH⁻.

What type of solution has equal concentrations of hydronium and hydroxide ions?
a) Acidic
b) Basic
c) Neutral
d) Alkaline

c) Søren Sørensen – He introduced the pH scale in 1909.

Who introduced the concept of pH in 1909?
a) Svante Arrhenius
b) Thomas Lowry
c) Søren Sørensen
d) Gilbert Lewis

a) It increases – As pH decreases, [H+] increases.

What happens to hydrogen ion concentration ([H+]) when pH decreases?
a) It increases
b) It decreases
c) It stays the same
d) It becomes neutral

b) A substance that changes color depending on pH – Acid-base indicators change color based on pH.

What is an acid-base indicator?
a) A device used to measure pH electronically
b) A substance that changes color depending on pH
c) A paper strip that measures temperature
d) A solution used to neutralize acids and bases