Chem 1010 CH 7
A soap molecule is ________. both polar and nonpolar primarily nonpolar a neutral compound primarily polar
A
A student is told to use 10.00 grams of sodium chloride to make an aqueous solution that has a concentration of 10.00 grams of sodium chloride per liter of solution. About how much water will she use in making this solution? .992 L 1.00 L 1.08 L
A
How is the solubility of a gas affected by temperature? As temperature goes down, the solubility goes up. As temperature goes down, the solubility goes down. As temperature goes up, the solubility stays the same. As temperature goes up, the solubility goes up.
A
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 1 gram 12.04 × 10^23 molecules of sucrose 6.02 × 10^23 molecules of sucrose 0.5 gram
A
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. The pressure goes down and the gas goes into the solvent. The solution is compressed and the gas is forced out of the solvent. The pressure goes down and the gas moves out of the solvent. The amount of gas in the solution would stay the same.
A
In a solution made from one teaspoon of sugar and one liter of water, which is the solute? sugar water both sugar and water the teaspoon
A
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. Yes, because sugar molecules are smaller than sodium or chloride ions. No, the molecular attractions between sugar and water are too strong. No, osmosis and reverse osmosis only apply to aqueous solutions containing ions.
A
Why does oxygen have such a low solubility in water? - Both of the answers are correct. -Water's attraction for itself is stronger than its attraction for oxygen molecules. -Water and oxygen only attract one another by means of weak dipole-induced dipole attractions. -Neither of the answers are correct.
A
Why might softened water not be good for some one who is trying to reduce their dietary sodium ion intake? - Water softeners work by replacing the calcium and magnesium ions of the water with sodium ions; softened water contains increased levels of sodium ions. -The potassium used in the softener to replace the calcium and magnesium ions increases the sodium retention in the body. -A person needs a certain level of calcium and magnesium in the water to help excrete the sodium from their body. - The softened water leaches sodium from the body, so a person might not be getting the dietary recommended levels of sodium
A
Why might softened water not be good for some one who is trying to reduce their dietary sodium ion intake? -Water softeners work by replacing the calcium and magnesium ions of the water with sodium ions; softened water contains increased levels of sodium ions. - A person needs a certain level of calcium and magnesium in the water to help excrete the sodium from their body. - The softened water leaches sodium from the body, so a person might not be getting the dietary recommended levels of sodium. -The potassium used in the softener to replace the calcium and magnesium ions increases the sodium retention in the body.
A
Two chemical structures are shown, one of a typical gasoline molecule and the other of a typical motor oil molecule. Which is which? h-c-c-c-c-c-c-c-c-c-c-c-c-c-c-h (& H on top & bottom) h-c-c-c-c-c-c-h (& h on top and bottom) Base your reasoning not on memorization but rather upon what you know about molecular interactions and the various physical properties of gasoline and motor oil. - Structure A represents the gas molecule because there are more bonds to gain energy from, giving it a higher energy content than oil. - Structure A represents motor oil, illustrating a molecule with greater induced dipole-induced dipole molecular interactions thus, the molecules are strongly attracted to one another giving the appearance of a thicker solution than gasoline. - Structure B represents the oil molecule. Because oil molecules are smaller, they can compact closer together, giving the appearance of a thicker solution than gasoline. - Structure B represents crude oil which is processed to generate longer molecules of gasoline to prevent toxic vapors from harming consumers.
B
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? - Water would move into the suspended bag and the size of the suspended bag would increase. - Water would move out of the suspended bag and the size of the suspended bag would decrease. - All of the answers are possible depending on the concentrations of the solutions. - The size of the bag would not change.
B
What is the sum of the atomic masses of all the atoms in sucrose, C12 H22 O11 182 amu 342 amu 270 amu None of the answers are correct.
B
Which of the following describes reverse osmosis in the desalination of water? - High pressure saltwater is reacted with aluminum, which absorbs the sodium ions in an oxidation reaction. - High pressure saltwater is forced against a semipermeable membrane and fresh water comes out. - The water is heated until it evaporates and condenses in a pure form. -Saltwater is chemically reacted with aluminum particles, which chemically binds to the chloride ions.
B
Which of the following would have the lowest melting point? CCl4 CF4 CBr4 CI4 (carbon tetraiodide) Not enough information is given.
B
Why is soap useful for removing nonpolar substances from your hands? - Soap is not useful because the nonpolar water molecules are attracted to the nonpolar molecules on 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. - Soap is necessary because it creates a film on the surface of your skin, shielding it from interacting polar water molecules. - None of the answers are correct.
B
How are oxygen molecules attracted to water molecules? - The attraction between oxygen and water molecules is a classic example of dipole-dipole interaction. - The attraction of oxygen and water molecules for one another is part of the common atom effect. Since both molecules contain oxygen, there is a built-in attraction. - As a water molecule is brought close to an oxygen molecule an induced dipole results in the O2 molecule causing the attraction. - The hydrogen bonding in water causes the attraction of the oxygen atoms in the O2 molecule to water.
C
How many moles of sugar, C12H22O11, are there in 200. grams? 0.684 moles 1.71 moles 0.585 moles 68,400 moles
C
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 bubbles are formed as the surrounding gases from the air dissolve into the water as it is heated. - They are very minute pockets of water in the gaseous phase. When they get large enough, the water will boil as this gas escapes. - 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. - These are dissolved salts heating up and escaping from the water.
C
Which of the following is the strongest form of intermolecular attraction between water molecules? You Answered ion-dipole covalent bonding hydrogen bonding induced dipole-induced dipole dipole-dipole
C
Which of the following molecules is most likely to show a hydrogen bonding interaction? H-CC-H CH3SH CH3OH A, B and C CH4
C
Which of the following solutions is the most concentrated? 0.1 liter of water with 1 gram of sugar 3 liters of water with 30 grams of sugar 0.5 liter of water with 50 grams of sugar They all have the same concentration. 2 liters of water with 0.2 gram of sugar
C
Which of the following would have the smallest number of induced dipole-induced dipole interactions? C12H26 C10H22 C6H14 Not enough information is given. C8H18
C
How many moles of water are there in 100. grams of water? 0.018 moles 1800 moles 100 moles 5.55 moles
D
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water? A- It is not very soluble because it is a gas, and all gases have very low solubility in water at room temperature. B- HCl is very soluble in water because it is such a small molecule, there is little electrical attraction to other HCl molecules. C- It is not very soluble because as a gas with low density, it floats to the surface of the water and then into the surrounding atmosphere. D- HCl is very soluble in water by virtue of the dipole/dipole attractions occurring between the HCl and H2O molecules.
D
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? 30 g 10 g 0 g 20 g 33 g
D
In a solution of 77 percent nitrogen and 23 percent oxygen, which is the solvent? neither oxygen Gases cannot form solutions. nitrogen both
D
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 bag would not change. - Water would move into the suspended bag and the size of the suspended bag would increase. - All of the answers are possible depending on the concentrations of the solutions. - Water would move out of the suspended bag and the size of the suspended bag would decrease.
D
Which has the most atoms? a mole of lead a mole of helium a mole of gold All of the above have the same number of atoms.
D
Which of the following is most likely to have the weakest induced dipole-induced dipole interaction? Br2 Cl2 I2 F2 All of the above have the same interactions.
D
Which of the following solutions is the most concentrated? 2.0 L of a 2 molar solution 0.5 L of a 1 molar solution 2.0 L of a 1 molar solution 0.5 L of a 3 molar solution
D
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 colder oxygen would "sink" and dissolve into the water. - There would be more dissolved oxygen in the tropical oceans because intense tropical storms mix up the atmospheric oxygen into the ocean water. - There would be more dissolved oxygen in the tropical oceans because the heated oxygen molecules in the air would collide with and mix into the water. - There would be more dissolved oxygen in the polar oceans because the solubility of oxygen in water decreases with increasing temperature.
D