Chapter 7

separation of charges

A dipole is a ________.

iron

A sample of steel is composed of 5 percent carbon and 95 percent iron. Which is the solvent?

Yes, compound X is more soluble than is compound Y because a greater concentration in water can be obtained.

A saturated solution of compound X in water has a greater concentration than does a saturated solution of compound Y. Does it follow that compound X is also more soluble in water?

Slightly less than 10 L

A student is told to use 10.00 grams of sodium chloride to make an aqueous solution that has a concentration of 1.00 grams of sodium chloride per liter of solution. How much water will she use in making this solution?

Because dimethyl ether lacks an -OH group, it is significantly less polar than is ethyl alcohol and is not readily soluble in water.

Account for the observation that ethyl alcohol, C2H5OH, dissolves readily in water but dimethyl ether, C2H6O, which has the same number and kinds of atoms, does not.

In order to smell something, the molecules must evaporate and reach your nose. If the new perfume doesn't evaporate, it will not have an odor.

An inventor claims to have developed a new perfume that lasts a long time because it doesn't evaporate. Comment on this claim.

Water is pushed upwards by osmostic pressure

Cells at the top of a tree have a higher concentration of sugars than cells at the bottom. How might this fact assist a tree in moving water upward from its roots?

Some of the solid comes out of the solution.

Describe what usually happens to a hot solution that is saturated with a solid as it cools.

The boiling process removes most of the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.

Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why

Solubility depends on the solvent's ability to overcome the intermolecular forces in a solid.

How are intermolecular forces and solubility related?

Add more sugar. If it does not dissolve after mixing, the solution is saturated.

How can you tell whether a sugar solution is saturated or not?

As temperature goes down, the solubility goes up.

How is the solubility of a gas affected by temperature?

It depends on the solid

How is the solubility of a solid affected by temperature?

45 g

How many grams of sodium chloride are needed to make 15 L of a solution that has a concentration of 3.0 g per liter of solution?

3.01 × 1023 molecules of sucrose

How many molecules of sucrose are in 0.500 L of a 1.00 molar solution of sucrose?

3.01 × 1023 molecules of sucrose

How many molecules of sucrose are in a 0.500 moles of sucrose?

HCl is very soluble in water by virtue of the dipole/dipole attractions occurring between the HCl and H2O molecules.

Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?

20 g

If the solubility of a compound is 30 grams per liter, how much solid is left undissolved if you mix 30 g of the compound in 0.33 L of solution?

36 g

If the solubility of a compound is 72 grams per liter at a given temperature, how many grams of the compound will dissolve in 0.50 liters at the same temperature?

0.125 L

If you need 3.01 × 1023 molecules of sucrose, how many liters of a 4.00 molar solution would you need?

sugar

In a solution made from one teaspoon of sugar and one liter of water, which is the solute?

all of them

In which of the following molecules will water induce a temporary dipole?

osmosis draws water into the cell until it pops

Red blood cells have a high concentration of dissolved ions. When placed into pure water they rupture. Why?

a chemical reaction

Treating water with chlorine or ozone during water purification is an example of ________.

low temperature and high pressure above the solution

Under which of the following conditions would you expect the highest solubility of oxygen gas in water?

The size of the suspended bag would decrease.

What happens if you were to place a dilute solution that is in a bag made of a semipermeable membrane and were to then suspend it in a very concentrated solution?

a special type of dipole-dipole attraction involving hydrogen bound to a highly electronegative atom

What is a hydrogen bond?

he water molecule aligns such that the oxygen interacts with the sodium.

What is happening at the molecular level when a polar molecule like water interacts with a typical sodium ion?

the number of moles of solute per liter of solution

What is molarity?

Both are similar, but one involves a temporary dipole created by a permanent dipole.

What is the main difference between a dipole-dipole interaction and a dipole-induced dipole interaction?

10. molar

What is the molarity of 0.50 liters of a solution with five moles of sucrose in it?

4 M

What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of solution?

the kinetic energy of the gas

What property primarily determines the effect of temperature on the solubility of gas molecules?

a mixture of some compound dissolved in water

Which of the following describes an aqueous solution?

an ion-dipole interaction

Which of the following is the strongest form of intermolecular attraction?

an induced dipole-induced dipole interaction

Which of the following is the weakest form of interatomic attraction?

CH3CH3

Which of the following might have the lowest solubility in water?

SO2

Which of the following molecules is most likely to show a dipole-dipole interaction?

(A) CH3OH

Which of the following molecules is most likely to show a hydrogen bonding interaction?

H-F

Which of the following molecules would you expect to be the most strongly attracted to a Cl- ion?

0.5 liter of water with 50 grams of sugar

Which of the following solutions is the most concentrated?

one liter of water with 10 grams of sugar

Which of the following solutions is the most concentrated?

They all have the same concentration.

Which of the following solutions is the most dilute?

I2

Which of the following would have the highest boiling point?

The magnitude of the electric charge associated with an ion is much greater.

Why are ion-dipole attractions stronger than dipole-dipole attractions?

Ionic bonds are so much stronger than the intermolecular attractions between covalently bonded compounds.

Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?

More water molecules enter the cell than leave the cell

Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals, burst when placed in fresh water?

The greater the surface area the greater the number of induced dipole-induced dipole forces of attraction that can occur between the gecko's foot and the surface.

Why is the surface area of a gecko's foot so extensive?

There would be more dissolved oxygen in the polar oceans because the solubility of oxygen in water decreases with increasing temperature

Would you expect to find more dissolved oxygen in polar or tropical ocean waters? Why?