Chem 1010 - Chapter 7
A 1 molar solution of sucrose (Formula Weight 342.6 g/mol) solution contains ________.
-1 mole of sucrose -342.6 g of sucrose -6.0210^{23 molecules of sucrose *all are correct*
Why might a solvent like turpentine be better for removing grease and grime than water?
-Like dissolves like. -Oil and grease have similar interatomic forces as the turpentine and so are more soluble. -Water is too polar and doesn't interact well with the nonpolar oils. -Oil and grease have very limited solubility in the water. *all of the above*
If you need 3.01 × 10^23 molecules of sucrose, how many liters of a 4.00 molar solution would you need?
0.125 L
Which of the following solutions is the most concentrated? (0.5 L of a 3 molar solution, 3.0 L of a 0.5 molar solution, 2.0 L of a 1 molar solution, 0.5 L of a 1 molar solution, 2.0 L of a 2 molar solution)
0.5 L of a 3 molar solution
Which of the following solutions is the most concentrated? (0.1 liter of water with 1 gram of sugar, 2 liters of water with 0.2 gram of sugar, 0.5 liter of water with 50 grams of sugar, 3 liters of water with 30 grams of sugar, They all have the same concentration.)
0.5 liter of water with 50 grams of sugar
How many moles of sugar, C12H22O11, are there in 200. grams?
0.585 moles
What is the molarity of 0.50 liters of a solution with five moles of sucrose in it?
10. molar
If you need 10. moles of sucrose, how many liters of a 4.0 molar solution would you need?
2.5 L
How many grams of sugar (sucrose) are there in 5.0 liters of sugar water that has a concentration of 0.50 grams per liter of solution?
2.5 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?
20 g
A solid has a solubility at room temperature of 78 grams per liter. If 1.0 L of a heated solution containing 100. g of solute is cooled to room temperature, how much solid is formed?
22 g
How many molecules of sucrose are in 0.500 L of a 1.00 molar solution of sucrose?
3.01 × 10^23 molecules of sucrose
How many molecules of sucrose are in a 0.500 moles of sucrose?
3.01 × 10^23 molecules of sucrose
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?
36 g
What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of solution?
4 M
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?
45 g
How many moles of water are there in 100 grams of water?
5.55 moles
How many molecules of sucrose are in 0.500 L of a 2.00 molar solution of sucrose?
6.02 × 10^23 molecules of sucrose
How can you tell whether a sugar solution is saturated or not?
Add more sugar. If it does not dissolve after mixing, the solution is saturated.
How is the solubility of a gas affected by temperature?
As temperature goes down, the solubility goes up.
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.
Because dimethyl ether lacks an -OH group, it is significantly less polar than is ethyl alcohol and is not readily soluble in water.
What is the main difference between a dipole-dipole interaction and a dipole-induced dipole interaction?
Both are similar, but one involves a temporary dipole created by a permanent dipole.
Chlorine is a gas at room temperature, but bromine is a liquid. Explain.
Bromine atoms are larger and this makes the formation of induced dipole-induced dipole attractions more favorable.
Which of the following would have the highest boiling point? (C6H14, C8H18, C10H22, C12H26)
C12H26
Which of the following would have the weakest induced dipole-induced dipole interactions? (C6H14, C8H18, C10H22, C12H26, not enough info given)
C6H14
Which of the following would have the lowest melting point? (CCl4, CBr4, CF4, CI4, not enough info given)
CF4
Which of the following might have the lowest solubility in water? CH3OH, Cl2, O2, CH3CH3, none of the above)
CH3CH3
Which of the following molecules is most likely to show a dipole-dipole interaction? (CH3OH, CH3SH, CH4, H-C-C-H, A and B)
CH3OH
Which of the following molecules is most likely to show a hydrogen bonding interaction? (CH3OH, CH3SH, CH4, H-C-C-H , A, B and C)
CH3OH
Which of the following is most likely to have the weakest induced dipole-induced dipole interaction? (Cl2, Br2, F2, I2, All of the above have the same interactions.)
F2
Which of the following molecules would you expect to be the most strongly attracted to a Cl- ion? (H-F, H3C-CH3, Cl-Cl, F-F, CCl4)
H-F
Which of the following molecules would you expect to be the least attracted to a Na+ ion? (H-F, H3C-CH3, Cl2CH2, F-, HO-)
H3C-CH3
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?
HCl is very soluble in water by virtue of the dipole/dipole attractions occurring between the HCl and H2O molecules.
Which of the following would have the highest boiling point? (Cl2, Br2, F2, I2, not enough information given)
I2
An inventor claims to have developed a new perfume that lasts a long time because it doesn't evaporate. Comment on this claim.
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.
Why are the melting temperatures of most ionic compounds far greater than the melting temperatures of most covalent compounds?
Ionic bonds are so much stronger than the intermolecular attractions between covalently bonded compounds.
How is the solubility of a solid affected by temperature?
It depends on the solid
What statement best describes a mole?
It is a very large number chemists use to count atoms or molecules.
Which of the following describes the term concentration?
It is the amount of solute in a given amount of solution.
Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals, burst when placed in fresh water?
More water molecules enter the cell than leave the cell.
Red blood cells have a high concentration of dissolved ions. When placed into pure water they rupture. Why?
Osmosis draws water into the cell until it pops.
Which of the following molecules is most likely to show a dipole-dipole interaction? (SO2, CO2, CH4, H-C-C-H)
SO2
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?
Slightly less than 10 L
How are intermolecular forces and solubility related?
Solubility depends on the solvent's ability to overcome the intermolecular forces in a solid.
Describe what usually happens to a hot solution that is saturated with a solid as it cools.
Some of the solid comes out of the solution.
Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why.
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.
If you were to increase the pressure of a gas above a liquid (such as by pressing a piston above a liquid) what happens?
The gas is forced into solution and the solubility increases.
Why is the surface area of a gecko's foot so extensive?
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.
If an ionic bond is stronger than a dipole-dipole interaction, how can water dissolve an ionic compound?
The ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it into the solution.
Why are ion-dipole attractions stronger than dipole-dipole attractions?
The magnitude of the electric charge associated with an ion is much greater.
Which of the following accurately describes osmosis?
The more concentrated solution absorbs water from the less concentrated solution.
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?
The size of the suspended bag would decrease
What happens if you were to place a concentrated solution into a bag made of a semipermeable membrane and were to then suspend it in a very dilute solution?
The size of the suspended bag would increase.
What is happening at the molecular level when a polar molecule like water interacts with a typical sodium ion?
The water molecule aligns such that the oxygen interacts with the sodium.
Would you expect to find more dissolved oxygen in polar or tropical ocean waters? Why?
There would be more dissolved oxygen in the polar oceans because the solubility of oxygen in water decreases with increasing temperature.
When you set a pot of tap water on the stove to boil, you'll often see bubbles start to form well before boiling temperature is ever reached. Explain this observation.
These initial bubbles are the gases that were dissolved in the water coming out of solution. The solubility of gases in water decreases with increasing temperature.
Which of the following solutions is the most dilute? (0.1 liter of water with 1 gram of sugar, 0.2 liter of water with 2 grams of sugar, 0.5 liter of water with 5 grams of sugar, 1 liter of water with 10 grams of sugar, They all have the same concentration.)
They all have the same concentration.
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?
Water is pushed upwards by osmostic pressure.
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?
Yes, compound X is more soluble than is compound Y because a greater concentration in water can be obtained.
Treating water with chlorine or ozone during water purification is an example of ________.
a chemical reaction
Which of the following describes an aqueous solution?
a mixture of some compound dissolved in water
A soap molecule is ________.
a molecular with both a polar and nonpolar part
What is a hydrogen bond?
a special type of dipole-dipole attraction involving hydrogen bound to a highly electronegative atom
In which of the following molecules will water induce a temporary dipole? (CO2, O2, N2, all of them, none of them)
all of them
Which of the following is the weakest form of interatomic attraction?
an induced dipole-induced dipole interaction
Of the following, which is the strongest form of intermolecular attraction?
an ion-dipole interaction
Hard water contains excessive amounts of ________.
calcium ions
The separation of charges within a polar molecule is called a(n) ________.
dipole
Under which of the following conditions would you expect the highest solubility of oxygen gas in water?
low temperature and high pressure above the solution
In a solution of 77 percent nitrogen and 23 percent oxygen, which is the solvent?
nitrogen
What is the difference between a dipole-dipole interaction and an ion-dipole interaction?
one involves dipole attraction between molecules while the other involves dipole interactions between molecules and ions
Which of the following solutions is the most dilute? (1L of water w/ 1 g of sugar, 1L of water w/ 2 g of sugar, 1L of water w/ 5 g of sugar, 1L of water w/ 10 g of sugar)
one liter of water with 1 gram of sugar
A dipole is a ________.
separation of charges
Fluorine is a relatively ________.
small atom
In a solution made from one teaspoon of sugar and one liter of water, which is the solute?
sugar
What property primarily determines the effect of temperature on the solubility of gas molecules?
the kinetic energy of the gas
During osmosis ________.
the water moves into the concentrated solution faster than it leaves
