Archive for February 2020

Formation of solutions where the process is endothermic can be spontaneously provided that

Formation of solutions where the process is endothermic can be spontaneously provided that



a. they are accompanied by another process that is exothermic
b. they are accompanied by an increase in order
c. they are accompanied by an increase in disorder
d. the solvent is a gas and the solute is a solid
e. the solvent is water and the solute is a gas


Answer: C

A sample of 2.05 g of polystyrene of uniform polymer chain length was dissolved in enough toluene to form 0.100 L of solution. The osmotic pressure of this solution was found to be 1.21 kPa at 25 C. Calculate the molar mass of the polystyrene.

A sample of 2.05 g of polystyrene of uniform polymer chain length was dissolved in enough toluene to form 0.100 L of solution. The osmotic pressure of this solution was found to be 1.21 kPa at 25 C. Calculate the molar mass of the polystyrene.



Answer: 4.20 x 10^4 g/mol

The osmotic pressure of an aqueous solution of a certain protein was measured to determine the protein's molar mass. The solution contained 3.50 mg of protein dissolved insufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25 C was found to be 1.54 torr. Treating the protein as a nonelectrolyte, calculate its molar mass.

The osmotic pressure of an aqueous solution of a certain protein was measured to determine the protein's molar mass. The solution contained 3.50 mg of protein dissolved insufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25 C was found to be 1.54 torr. Treating the protein as a nonelectrolyte, calculate its molar mass.



Answer: 8.45 x 10^3 g/mol

If the pure water in the left arm of the U-tube is replaced by a solution more concentrated than the one in the right arm, what will happen?

If the pure water in the left arm of the U-tube is replaced by a solution more concentrated than the one in the right arm, what will happen?


A. Nothing
B. Water flows through the semipermeable membrane from the more dilute solution to the more concentrated solution and the liquid level in the left arm rises.
C. Water flows through the semipermeable membrane from the more concentrated solution to the more dilute solution and the liquid level in the right arm rises.


Answer: B

Automotive antifreeze consists of ethylene glycol, CH2(OH)CH2(OH), a nonvolatile nonelectrolyte. Calculate the boiling point and freezing point of a 25.0 mass % solution of ethylene glycol in water.

Automotive antifreeze consists of ethylene glycol, CH2(OH)CH2(OH), a nonvolatile nonelectrolyte. Calculate the boiling point and freezing point of a 25.0 mass % solution of ethylene glycol in water.



Answer:

Boiling point = 102.7 C
Freezing point = -10.0 C

Predict whether each of the following substances is more likely to dissolve in the nonpolar solvent carbon tetrachloride (CCl4) or in water: C7H16, Na2SO4, HCl, and I2.

Predict whether each of the following substances is more likely to dissolve in the nonpolar solvent carbon tetrachloride (CCl4) or in water: C7H16, Na2SO4, HCl, and I2.



Answer: C7H16 and I2 (the nonpolar solutes) would be more soluble in the nonpolar CCl4 than in polar H2O, whereas water would be the better solvent for Na2SO4 and HCl (the ionic and polar covalent solutes

Why Do Endothermic Processes Occur?

Why Do Endothermic Processes Occur?



Answer: the energy of the system is lowered, heat is absorbed

Three processes that affect the energetic of solution

Three processes that affect the energetics of the solution.



Separation of solute particles, Separation of solvent particles, and New interactions between solute and solvent.

How Does a Solution Form between salt and water?

How Does a Solution Form between salt and water?



Answer: because the ion-dipole interactions are strong enough to overcome the lattice energy of the salt crystal
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