Practice Questions

Question 1

Many foods must be refrigerated to prevent spoiling (microbialgrowth). Explain why honey (which is approx. 82% carbohydrate by weight) resists microbial growth even at room temperature.

Answer 1

Honey has a high solute concentration which will draw water out of microorganisms by osmosis, preventing growth of microorganisms.

Question 2

Patients with kidney failure frequently develop metabolic acidosis.If such patients undergo dialysis, the dialysate includes sodium bicarbonate at a concentration higher than that of the blood. Explain why this would benefit the patient.

Answer 2

Higher concentration in dialysis bag would diffuse into blood of patient allowing bicarbonate to neutralise excesss H+.

Question 3

How do you work out the pH of a solution containing both acid and amino acid?

Answer 3

1. Recognise that the amino acid will like act as a buffer, mopping up excess H+.
2. Calculate moles of amino acid, calculate moles of H+.
3. Subtract moles of amino acid from moles of H+ to give leftover moles of H+.
4. Convert to pH.