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11 MDCAT Chemistry questions with answers and explanations.
Printable worksheet with answer key
What is the pH of 0.01 M hydrochloric acid?
Correct answer: 2
HCl is a strong acid, so [H+] = 0.01 = 10^-2 and pH = 2.
What is the pH of 0.001 M sodium hydroxide at 25 degrees C?
What is the conjugate base of H2SO4?
Correct answer: HSO4-
When H2SO4 gives away one proton it becomes HSO4-, which is its conjugate base.
For N2 + 3H2 <-> 2NH3, increasing the pressure shifts the equilibrium:
Correct answer: To the right
The forward reaction reduces 4 moles of gas to 2 moles. Higher pressure favours the side with fewer gas moles, so it shifts right.
A buffer solution is made of:
Correct answer: A weak acid and its salt
A weak acid and its conjugate base resist large changes in pH when small amounts of acid or base are added.
What is the pOH of a solution whose pH is 4 at 25 degrees C?
Which expression gives the solubility product Ksp of AgCl?
Correct answer: [Ag+] x [Cl-]
For a sparingly soluble salt, Ksp is the product of the ion concentrations at saturation.
A larger value of Ka means that the acid is:
Correct answer: Stronger
Ka measures how far an acid ionises. A larger Ka means more ionisation, so a stronger acid.
The pH of a solution with a hydrogen ion concentration of 1 × 10⁻³ mol/dm³ is:
A buffer solution is one that:
Correct answer: Resists a change in pH when small amounts of acid or base are added
A buffer contains a weak acid and its salt (or a weak base and its salt) and keeps the pH almost constant.
For the reaction N₂ + 3H₂ ⇌ 2NH₃ (exothermic), increasing the pressure shifts the equilibrium:
Correct answer: Towards ammonia
Four moles of gas on the left become two on the right, so higher pressure favours ammonia.