Test Your Understanding

Which of the following is the meaning of acid?

• Chemical substances ionise in water to produce hydroxide ions

• Chemical substances ionise in water to produce oxygen gas

• Chemical substances ionise in water to produce hydrogen ions

• Chemical substances ionise in water to produce salt

Which of the following substances is a diprotic acidic?

• Hydrochloric acid

• Phosphoric acid

• Nitric acid

• Sulphuric acid

Which of the following particles in hydrochloric acid is responsible for its acidity?

• Oxide ion, $O^2\ ^-$

• Hydrogen ion, $H^+$

• Hydroxide ion, $OH^-$

• Chloride ion, $Cl^-$

Which of the following is the chemical equation to show the ionisation of ammonia in water?

• $NH_3\left(aq\right)+H_2O\left(l\right)\rightarrow NH_4\ ^+\left(aq\right)+OH^-\left(aq\right)$

• $NaOH\left(aq\right)\rightarrow Na^+\left(aq\right)+OH^-\left(aq\right)$

• $H_2SO_4\left(aq\right)\rightarrow2H^+\left(aq\right)+SO_4\ ^2\ ^-\left(aq\right)$

• $HNO_3\left(aq\right)\rightarrow H^+\left(aq\right)+NO_3\ ^-\left(aq\right)$

The presence of water causes hydroxide ions,  $OH^-$   to be produced and alkalis are able to move freely. True or false?

• True

• False

pH value more than 7 is alkaline. True or false?

• True

• False

What is the pH value of 0.002 mol  $dm^{-3}$  hydrochloric acid?

• 5.4

• 2.6

• 2.7

• 3.7

Determine the pH value for potassium hydroxide,  $KOH$  with concentration of 0.05 mol  $dm^{-3}$  

• 12.8

• 13.7

• 13.6

• 12.7

Determine the molarity of sodium hydroxide solution, NaOH with pH value of 13

• $1\times10^{-13}\ mol\ dm^{-3}$

• $1.0\ mol\ dm^{-3}$

• $0.1\ mol\ dm^{-3}$
  

• $0.01\ mol\ dm^{-3}$

Which of the following statement is TRUE?

• The higher the concentration of hydroxide ions, $OH^-$ , the higher the pH value

• The higher the concentration of hydrogen ions, $H^+$ , the higher the pH value

• The higher the concentration of hydroxide ions, $OH^-$ , the lower the pH value

• The higher the concentration of hydrogen ions, $H^+$ , pH value $=$ 7