solutions
If you need 3.01 × 1023 molecules of sucrose, how many liters of a 4.00 molar solution would you need?
0.125 l
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?
3.01 × 1023 molecules of sucrose
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?
45g
How many molecules of sucrose are in 0.500 L of a 2.00 molar solution of sucrose?
6.02 × 1023 molecules of sucrose
In which of the following molecules will water induce a temporary dipole?
All of the molecules.
How are oxygen molecules attracted to water molecules?
As a water molecule is brought close to an oxygen molecule an induced dipole results in the O2 molecule causing the attraction.
How is the solubility of a gas affected by temperature?
As temperature goes down, the solubility goes up
Which of the following would have the lowest melting point?
CF4
Which of the following molecules would you expect to be the most strongly attracted to a Cl- ion?
H-F
Which solute graphed above has a solubility in water that does not markedly increase with increasing temperature?
NaCl
Given the following diagram, describe what happens electronically between these two molecules.
Oxygen A becomes slightly positively charged due to the protons on the water molecule.
Many solvents expand to occupy greater volumes with increasing temperature. What happens to the concentration of a solution made with such a solvent as its temperature is increased?
Since concentration depends on how much mass is dissolved in a given volume, as the volume increases, the concentration decreases.
Why is soap useful for removing nonpolar substances from your hands?
Soap is necessary because it has both a polar and nonpolar end to interact with the nonpolar molecules on your hands and the polar water molecules.
If nitrogen, N2, were pumped into your lungs at high pressure, what would happen to its solubility in your blood stream?
The greater the pressure, the greater the solubility.
Which of the following statements best describes what is happening in a water softening unit
The hard ions in water are exchanged for ions like sodium that do not interact as strongly with soaps.
What is the special property of a semipermeable membrane that makes osmosis possible?
The pores in the membrane only allow water to pass through.
What happens when the molecule-to-molecule attractions in the solute are comparable to those in the solvent?
The solute can have infinite solubility in the solvent.
What is the purpose of adding aluminum salts and a base to water during water treatment?
The two together gel and trap dirt and bacteria.
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.
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.
Might reverse osmosis be used to obtain fresh water from a sugar-water solution?
Yes, reverse osmosis can be applied to any aqueous solution for the generation of fresh water.
Why might a solvent like turpentine be better for removing grease and grime than water?
all of the above
Hard water contains excessive amounts of ________
calcium and magnesium ions
Fatty acid molecules can also align to form a bilipid layer that extends in 3-dimensions. Shown below is a cross section of this structure. What is this structure called? (Hint: It forms the basis of all life.)
cell
A sample of steel is composed of 5 percent carbon and 95 percent iron. Which is the solvent?
iron
What is the difference between a dipole-dipole interaction and an ion-dipole interaction?
one involves dipole attraction between polar molecules while the other involves dipole interactions with ions
Which of the following best describes a two-molar sucrose solution?
one liter of solution that contains 2 moles of sucrose
Which of the following solutions is the most dilute?
one liter of water with 1 gram of sugar
In a solution made from one teaspoon of sugar and one liter of water, which is the solute?
sugar