Question

(a) Explain the following phenomena with the help of Henry’s law.

$\left(i\right)$ Painful condition known as bends.

$\left(ii\right)$ Feeling weak and discomfort in breathing at high altitudes.

(b) Why soda water bottle kept at room temperature fizzes on opening?

Answer 1

$\left(A\right)$ $\left(i\right)$

• The solubility of a gas in a liquid increases with increase in pressure.
• Deep sea divers must breathe air under high pressure underwater. Nitrogen gas is not soluble at normal pressure. Due to high pressure underwater, nitrogen dissolves in blood. When the divers come towards the surface, the pressure gradually decreases this releases the dissolved gases and leads to the formation of bubbles of nitrogen in the blood. This blocks the capillaries and creates a medical condition known as bends.

$\left(ii\right)$

• At high altitudes, the partial pressure of oxygen is less than that at the ground level.
• This leads to low concentrations of oxygen in the blood and tissues of people living at high altitudes or climbers.
• So, low blood oxygen levels make the climbers feel weak and cause discomfort in breathing at high altitudes.

$\left(B\right)$

• To increase the solubility of $C{O}_2$ in soft drinks, the soda water bottles are sealed under high pressure.
• When a soda water bottle kept at room temperature is opened to air, the partial pressure of $C{O}_2$ ​above the solution decreases suddenly because the atmospheric pressure is lower than the pressure inside the bottle.
• This results in a decrease in the solubility of $C{O}_2$ and hence, excess $C{O}_2$ escapes the bottle with a fizz.