What is the pH of a 0.50 M HF solution? a. 13.70 b. 10.53 c. 1.73 d. 0.30 Water

Question

What is the pH of a 0.50 M HF solution? a. 13.70 b. 10.53 c. 1.73 d. 0.30 Water and diethyl ether (CH_3CH_2OCH_2CH_3) are only slightly miscible because a. These liquids have very different densities. b. One compound is polar and the other is nonpolar. c. They both have polar bonds, but one is incapable of forming hydrogen bonds. d. Hydrogen bonding between the molecules increases solvent-solute interactions. The weaker the intermolecular forces in a substance a. the higher the boiling point. b. the lower the freezing point. c. the lower the vapor pressure. d. the larger the deviation from ideal gas behaviour. Although BaSO_3 is not very soluble in water, it dissolves more readily in 0.10 M HCl because a. HCl is a weak acid. b. BaSO_3 is a weak base. c. BaSO_3 will form a complex ion. d. BaSO_3 will precipitate. Which conditions favor a low solubility of a gas in a liquid? a. high pressure, high temperature b. high pressure, low temperature c. low pressure, high temperature d. low pressure, low temperature

Explanation / Answer

1.Ka for HF= 6.6*10-4,

Given solution is 0.5M

HF+ H2O------>F- + H3O+

Ka= [F-] [H3O+]/[HF]

Let x= drop in concentration of HF to reach equilibrium

At equilibrium [HF]= 0.5-x, [F-]=[H3O+]=x

Hence x2/ (0.5-x)= 6.6*10-4 , when solved using excel, x= 0.0179, pH= -log (0.0179)= 1.74 ( c is correct)

2. the presence of oxygen in diethyl ether makes diethyl ether react with hydrogen of oxygen. This makes diethyl ether to be slightly soluble in water. ( d is correct)

3.due to weaker intermolecular forces allows less heat is required to change the state. Hence lower the boiling point and hence higher vapor pressure. Freezing point will be higher and hecne deviations from ideality is more. ( D is correct)

4. the chemical reaction between BaSO3 and HCl is BaSO3+2 HCl ------->BaCl2+ SO2+H2O

BaCl2 is soluble in water while BaSO3 is not.

5. With an increase in pressure, the gas volume decrease and hence more gas molecules can dissolve in liquid and as the temperature is decreased, the kinetic energy of gas molecule decreased and hence solubility increases.

so high pressure and low temperature favors solubility of gas in liquid

3.

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