Advertisements
Advertisements
Question
The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if the Henry’s law constants for oxygen and nitrogen are 3.30 × 107 mm and 6.51 × 107 mm respectively, calculate the composition of these gases in water.
Advertisements
Solution
Total pressure of air in equilibrium with water = 10 atmosphere
As air contains 20% oxygen and 79% nitrogen by volume,
∴ Partial pressure of oxygen, `(P_(O_2)) = 20/100 xx 10` atm
= 2 atm
= 2 × 760 mm Hg
= 1520 mm Hg
Partial pressure of nitrogen, `(P_(N_2)) = 79/100 xx 10` atm
= 7.9 atm
= 7.9 × 760 mm Hg
= 6004 mm Hg
Now, according to Henry’s law:
P = KH . χ
For oxygen:
`P_(O_2) = K_H xx chi_(O_2)`
⇒ `chi_(O_2) = P_(O_(2))/K_H`
= `(1520 "mm Hg")/(3.30 xx 10^(7) "mm Hg")` ...(Given KH = 3.30 × 107 mm Hg)
= 4.61 × 10−5
For nitrogen:
`P_(N_2) = K_H xx chi_(N_(2))`
⇒ `chi_(N_(2)) = P_(N_(2))/K_H`
= `(6004 "mm Hg")/(6.51xx10^(7) "mm Hg")` ...(Given KH = 6.51 × 107 mm Hg)
= 9.22 × 10−5
Hence, the mole fractions of oxygen and nitrogen in water are 4.61 × 10−5 and 9.22 × 10−5, respectively.
RELATED QUESTIONS
What is the effect of temperature on solubility of a gas in a liquid?
Explain, why do aquatic animals prefer to stay at lower level of water during summer?
Henry’s law constant for CO2 in water is 1.67 × 108 Pa at 298 K. Calculate the quantity of CO2 in 500 mL of soda water when packed under 2.5 atm CO2 pressure at 298 K.
The partial pressure of ethane over a solution containing 6.56 × 10−3 g of ethane is 1 bar. If the solution contains 5.00 × 10−2 g of ethane, then what shall be the partial pressure of the gas?
Based on solute-solvent interactions, arrange the following in order of increasing solubility in n-octane and explain.
Cyclohexane, KCl, CH3OH, CH3CN
Henry’s law constant for the molality of methane in benzene at 298 K is 4.27 × 105 mm Hg. Calculate the solubility of methane in benzene at 298 K under 760 mm Hg.
Give reasons for the following :
Aquatic animals are more comfortable in the cold water than in warm water.
A solution is prepared by dissolving 9.25 g of non-volatile solute in 450 mL of water. It has an osmotic pressure of 350 mm of Hg at 27°C. Assuming the solute is non-electrolyte, determine its molecular mass. (R = 0.0821 Lit-atm K−1 mol−1)
The statement “If 0.003 moles of a gas are dissolved in 900 g of water under a pressure of 1 atmosphere, 0.006 moles will be dissolved under a pressure of 2 atmospheres”, illustrates.
According to Henry’s law, the amount of gas that will dissolve in blood plasma or any other liquid is determined by which of these factors?
Henry’s law constant of oxygen is 1.4 × 10–3 mol lit–1 atm–1 at 298 K. How much of oxygen is dissolved in 100 ml at 298 K when the partial pressure of oxygen is 0.5 atm?
Solubility of gases in liquids decreases with rise in temperature because dissolution is an ______.
Match the items given in Column I with the type of solutions given in Column II.
| Column I | Column II |
| (i) Soda water | (a) A solution of gas in solid |
| (ii) Sugar solution | (b) A solution of gas in gas |
| (iii) German silver | (c) A solution of solid in liquid |
| (iv) Air | (d) A solution of solid in solid |
| (v) Hydrogen gas in palladium | (e) A solution of gas in liquid |
| (f) A solution of liquid in solid |
The solubility of a gas in water depends on ______
If O2 gas is bubbled through water at 303 K, the number of millimoles of O2 gas that dissolve in 1 litre of water is ______. (Nearest integer)
(Given: Henry's Law constant for O2 at 303 K is 46.82 k bar and partial pressure of O2 = 0.920 bar)
(Assume solubility of O2 in water is too small, nearly negligible)
Henry's constant (in k bar) for four gases α, β, γ and δ in water at 298 K is given below:
| α | β | γ | δ | |
| KH | 50 | 2 | 2 × 10-5 | 0.5 |
(density of water = 103 kg m-3 at 298 K)
This table implies that:
Solubility of gas in liquid decreases with increase in ______.
Amongst the following compounds, identify which are insoluble, partially soluble and highly soluble in water?
- phenol
- toluene
- formic acid
- ethylene glycol
- chloroform
- pentanol
