Exam 2 Review Questions
The dog is smelling molecules from the cat.
A cat strolls across your back yard. An hour later, a dog with its nose to the ground follows the trail of the cat. Explain what is going on from a molecular point of view. The dog is following the areas of increased density of the earth. The dog is smelling atoms from the cat. The dog is smelling molecules from the cat. The cat is leading the dog into a trap.
separation of charges
A dipole is a ________. separation of charges molecule with parallel bonds nonpolar entitiy form of electronegativity
takes a lot of energy to change its temperature
A material with a high specific heat ________. takes a lot of energy to change its temperature melts at a high temperature rapidly cools, giving up its heat changes temperature very rapidly when heated takes a very small temperature change to change the amount of heat in a material
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? No, the greater the concentration of a compound in water, the less soluble it is. Yes, compound X is more soluble than is compound Y because a greater concentration in water can be obtained. No, concentration of a solution is not correlated with how soluble that solution is in water. Since both solutions are saturated, it cannot be determined which compound has a greater solubility.
3,000 joules
A walnut stuck to a pin is burned beneath a can containing 100.0 grams of water at 21°C. After the walnut has completely burned, the water's final temperature is a warmer 28°C. How much heat energy arose from the burning walnut? 3,000 joules 9,000 joules 5,000 joules 2,000 joules
fissionable Pu-239 is formed as the U-238 absorbs neutrons from the fissioning U-235
After a uranium fuel rod reaches the end of its fuel cycle (typically 3 years. most of its energy comes from the fissioning of plutonium because ________. fissionable Pu-239 is formed as the U-238 absorbs neutrons from the fissioning U-235 fissionable Pu-239 is formed as the U-235 absorbs neutrons from the fissioning U-238 fissionable Pu-239 is formed as the U-238 absorbs alpha particles from the fissioning U-235 fissionable Pu-239 is formed as the U-235 absorbs alpha particles from the fissioning U-238
attraction between two different molecules
An adhesive force is best described as ________. attraction between two liquid molecules attraction between a liquid molecule and a solute the force that allows for molecular adhesion the force that holds together the nucleus attraction between two different molecules
chemical change involving the formation of ions
An atom loses an electron to another atom. Is this an example of a physical or chemical change? physical change involving the formation of negative ions chemical change involving the formation of neutral atoms physical change involving the formation of positive ions chemical change involving the formation of ions
Two of the above are reasonable.
Antarctica, which is mostly ice, is much colder than the Arctic, which is a mixture of ice and water. Why? The liquid water of the Arctic Ocean absorbs and releases a lot of heat that keeps the temperatures in that region from fluctuating. The Arctic is much farther north than the Antarctic. The salt in the water of the Antarctic keeps the water from freezing. The specific heat of the ice is less than that of liquid water, which allows its temperature to change more readily. Two of the above are reasonable.
Ba3N2
Barium ions carry a 2+ charge, and nitrogen ions carry a 3-charge. What would be the chemical formula for the ionic compound barium nitride? Ba3N2 Ba2N3 Ba3N4 Ba2N2
Nitrogen atoms are bigger and so nitrogen molecules should be more soluble in water due to greater dipole-induced dipole attractions.
Based on atomic size, which would you expect to be more soluble in water: helium, He, or nitrogen, N2? Although He is smaller, its outer orbital is filled and the atom will have little attraction to the water molecules. Since He atoms are smaller, more of them can fit into solution, so it has a higher solubility in water. Nitrogen atoms are bigger and so nitrogen molecules should be more soluble in water due to greater dipole-induced dipole attractions. He atoms are bigger and so helium molecules should be more soluble in water due to greater dipole-induced dipole attractions.
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? Cells with high concentrations of sugar are more dense. As these cells migrate downwards, cells containing fresh water are able to migrate upwards. Water is pushed upwards by osmostic pressure. It doesn't. In fact, water makes it to the top of a tree because that is where the water molecules are being evaporated. Fresh water is drawn upwards to the sugar containing cells by way of dipole-dipole molecular interactions.
the coal-fired power plant contains none of the radiation it releases
Coal contains only minute quantities of radioactive materials, yet there is more environmental radiation surrounding a coal-fired power plant than a fission power plant. This indicates that ________. the coal-fired power plant's radiation shields need to be strengthened the coal-fired power plant has been contaminated the coal-fired power plant contains none of the radiation it releases the news media is biased in its coverage
It grows more dense and sinks towards the bottom.
Consider a lake that is uniformly 10°C. What happens to the oxygen-rich surface water as it cools down to 4°C? The oxygen gets squeezed out as the microcrystals form. Its rate of evaporation decreases which has the effect of increasing the oxygen concentration. It grows less dense and remains at the surface. It grows more dense and sinks towards the bottom.
the molecule on the far left because the O-H bond is polar and the carbon and hydrogen bonds are nonpolar
Dipole-induced dipole forces of attraction exist between water and gasoline, and yet these two substances do not mix because water has such a strong attraction for itself. Which of the following compounds might best help to make these two substances mix into a single liquid phase? the molecule on the far left because the O-H bond is polar and the carbon and hydrogen bonds are nonpolar the molecule in the middle because when the salts mix into the water, it will help separate the water and decrease the attraction for itself The molecule on the right will form attractions with the polar ends of the water, allowing the gasoline a chance to mix with the water. All of these molecules would be equally effective at increasing the mixing of gasoline and water.
The average distance increases while the probability of an explosion also increases.
Does the average distance that a neutron travels through fissionable material before escaping increase or decrease when two pieces of fissionable material are assembled into one piece? Does this assembly increase or decrease the probability of an explosion? The average distance increases while the probability of an explosion also increases. The average distance decreases while the probability of an explosion decreases. The average distance increases while the probability of an explosion decreases. The average distance decreases while the probability of an explosion increases.
the water moves into the concentrated solution faster than it leaves
During osmosis ________. the water moves into the concentrated solution faster than it leaves the ions move into the concentrated solution faster than they leave the water moves more slowly into the concentrated solution than it leaves the ions move into the concentrated solution slower than they leave all of the above
The boiling process removes 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. There is now a higher concentration of dissolved CO2 in the water. The nutrients in the water have been destroyed. Since some of the water was evaporated while boiling, the salts in the water are now more concentrated. This has a negative effect on the fish. The boiling process removes the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.
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? Add more sugar, if it dissolves, it is saturated. There will be a precipitate if the water is heated. As long as there are more water molecules than sugar molecules, there is a saturated solution. Add more sugar. If it does not dissolve after mixing, the solution is saturated.
Solutes slow the rate of ice formation.
How does a solute such as salt or sugar affect the melting and freezing of water? Solutes slow the rate of ice formation. Solutes increase the rate of ice formation. Solutes slow the rate of liquid water release from ice. Solutes increase the rate of liquid water release from ice. none of the above
3
How many covalent bonds would the following atom usually form? 3 2 1 5 would usually not form any covalent bonds
10
How many electrons are used to draw the electron-dot structure for acetylene, a covalent compound with the formula, C2H2? 5 8 10 12
2.5g
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? 50g 25g 2.5g 1.5g
6.02 × 10^23 molecules of sucrose
How many molecules of sucrose are in 0.5 00L of a 2.00 molar solution of sucrose? 3.01 × 10^23 molecules of sucrose 6.02 × 10^23 molecules of sucrose 12.04 × 10^23 molecules of sucrose 0.5 1 gram
7
How many valence electrons does bromine (Br, atomic no. = 35. have? 1 7 21 28 35
48 hours
If a material has a half-life of 24 hours, how long do you have to wait until the amount of radioisotope is 1/4 its original amount? 12 hours 24 hours 48 hours 72 hours practically forever, but it may be safe by then
D
If all of the capillaries pictured above were the same size diameter, which would contain the liquid with the greatest capillary action? a b c d e
No, because there would be no molecules traveling to our nose.
If all the molecules of a body remained part of that body, would the body have any odor? Yes, but only if that body is sweating. No, because there would be no molecules traveling to our nose. Yes, because it would still release photons. No, because it would no longer be what it was.
The approximate atomic mass is 261.
If an atom has 104 electrons, 157 neutrons, and 104 protons, what is its approximate atomic mass? The approximate atomic mass is 365. The approximate atomic mass is 261. The approximate atomic mass is 157. The approximate atomic mass is cannot be determined with the information given.
The greater the pressure, the greater the solubility.
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. The greater the pressure, the lower the solubility. You cannot change solubility of a substance by changing the pressure. Nitrogen is not soluble in your blood.
would probably not ionize
If the following generic atom were to undergo ionization, what would the most likely product be? +1 -2 -3 +4 would probably not ionize
3.3 J
If the specific heat of gold is 0.13 J/(g°C., how much heat does it take to raise the temperature of a 1.0-gram piece of gold from 74°C to 99°C? 3.3 J 9.75 J 13.0 J 75,000 J 192 J
0.125L
If you need 3.01 × 10^23 molecules of sucrose, how many liters of a 4.00 molar solution would you need? 0.125L 0.250L 4.00L 1.00L none of the above
The gas is forced into solution and the solubility increases.
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 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 pressure goes down and the gas goes into the solvent. The amount of gas in the solution would stay the same.
CF4, CCl4, CBr4, CI4,
List the following compounds in order of increasing boiling point: CI4, CBr4, CCl4, CF4. CI4, CBr4, CCl4, CF4 CF4 CBr4 CCl4 CI4 CI4, CCl4, CBr4, CF4 CF4, CCl4, CBr4, CI4,
gamma radiation
People who work around radioactivity wear film badges to monitor the amount of radiation that reaches their bodies. These badges consist of small pieces of photographic film enclosed in a light-proof wrapper. What kind of radiation do these devices monitor? alpha radiation beta radiation gamma radiation all of the above
emit radiation
Radioactivity is a tendency for an element or a material to ________. emit radiation emit light emit electrons glow in the dark radiate heat
Radium-226 is a "daughter" isotope and the result of the radioactive decay of uranium.
Radium-226 is a common isotope on Earth, but has a half-life of about 1600 years. Given that Earth is some 5 billions years old, why is there any radium at all? Radium-226 is one of several self-transmutating isotopes of the elements of the periodic table and is able to replenish itself so that it is never depleted. Radium-226 and Radium-218 undergo a series of transmutation reactions of alpha and beta decay to repeatedly become one another approximately every 1600 years. Radium-226 is a "daughter" isotope and the result of the radioactive decay of uranium. Radium-226 and Astatine-218 are converted back and forth via transmutation to one another at each of their respective half-life cycles.
Distilled water is relatively pure water, which loses its purity once it mixes with everything else in your stomach.
Some people fear drinking distilled water because they have heard it leaches minerals from the body. What scientifically sound information might be offered to such a person? add small amounts of salt to the distilled water before drinking it chill the distilled water to decrease its leaching potential buy distilled water that has also undergone reverse osmosis Distilled water is relatively pure water, which loses its purity once it mixes with everything else in your stomach.
how two or more atoms are held together
The concept of a chemical bond is ________. how two or more atoms are held together the sharing of nucleons how two or more electrons reside in an orbital how much energy it takes to remove an electron from a set of atoms none of the above
Both A and B
The element uranium (U, atomic no. = 92. often has 146 (or more. neutrons but it will still undergo radioactive decay. Which statement might best describe why? The attractive forces of the nucleons have a limited range. Any isolated neutron is not stable and will undergo spontaneous transformation into a proton and an electron. The force is strong with U, but tainted with the dark side it is. both A and B None of the above
greater the polarity of the bond between them
The farther apart two elements are located from each other in the periodic table, the ________. greater the polarity of the bond between them more metallic is the nature of the bond between them more covalent is the nature of the bond between them weaker is the bond that can form between them
amount of heat required to change the temperature of a given mass
The specific heat of a substance is the ________. amount of heat required to change the temperature of a given mass amount of heat energy that is stored in chemical bonds amount of potential energy in a material that is released when a substance undergoes combustion and gives off heat temperature at which a compound starts to melt temperature at which a given mass's heat increases
All of the above
There is more gold in 1 km3 of the ocean than the amount of gold mined in all of recorded history. How come we do not mine the oceans? It is too dilute to separate. It would take too much energy. It would cost too much. all of the above none of the above
find the change in mass and multiply by the speed of light squared
To predict the approximate energy release of either a fission or a fusion reaction, explain how a physicist uses a table of nuclear masses and the equation E = mc2. find the change in mass and divided by the speed of light squared find the change in mass and multiply by the speed of light squared find the change in mass, square it, and multiply by the speed of light take the square root of the change in mass and multiply by the speed of light
A physical separation
Water being purified using aluminum salts and a base is an example of ________. a physical separation a chemical reaction an acid-base reaction a chemical separation none of the above
The size of the suspended bag would increase.
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 decrease. The size of the suspended bag would increase. The size of the bag would not change. The solutions would eventually reach the same concentration. only C and D
The soda can puffs out and sometimes the lid pops open because water expands when it freezes.
What happens to a soda can left in the freezer? Why? The sugar and syrup, which separate from the water, settle to the bottom of the can and become solid. The soda inside the can freezes collapsing the can as the solid forms. The soda can puffs out and sometimes the lid pops open because water expands when it freezes. Although the soda inside the can get s very cold, it will not completely freeze because of the high sugar concentration.
It is the time it takes for 1/2 of the material to undergo radioactive decay.
What is a half-life? It is the time it takes for 1/2 of the material to undergo radioactive decay. It is the time needed until 1/2 of the radiation is gone. It is the time it takes for 1/2 of the material to decompose. It is half of the lifetime of the radioactivity in a sample. all of the above
They take part in the formation of different types of bonds.
What is one role of unpaired valance electrons? They take part in the formation of different types of bonds. They keep the paired electrons separated to minimize interaction. They are the nonbonding electrons. They provide the number of Lewis dots. They tell us which Lewis dot structure is correct.
K2S
What is the compound that forms if you react potassium and sulfur? K2S KS SP PS2 SkP
Hydrogen bonding
What is the leading cause of surface tension in water? hydrogen bonding ion-dipole interactions solvation evaporation
Soaps are made from fatty acids, detergents are synthetic.
What is the main difference between a soap and a detergent? Soaps are made from fatty acids, detergents are synthetic. Soaps are biodegradable, detergents are not. Detergents are better than soaps. Soaps are all natural. Soaps and detergents are exactly the same.
4m
What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of solution? 8m 4m 5m 2.5m
Phosphate
What is the name for the following polyatomic ion? PO43- phosphate phosphorus oxide phosphinate trioxo phosphoride potassium
45°C
What is the temperature change if you heat water from 55°C to 100°C? 55°C 100°C 45°C -45°C -55°C
One is the sharing of a pair of electrons, the other is the transfer of at least one electron.
What it the main difference between an ionic and a covalent bond? One is the sharing of a pair of electrons, the other is the transfer of at least one electron. One involves electrons, the other does not involve any electrons. The electrons in both types of bonding undergo an exchange. The electrons are traded between the two atoms and this keeps the atoms close. Both bonds are the same, but named different to describe different atoms involved.
Both A and B
What property of half-lives makes radioactive material so problematic? There is no known way to shorten a half-life. Radioactivity is limited by the natural decay-time to stable isotopes. All half-lives are long. There is no known way to measure half-lives with any accuracy. both A and B
The kinetic energy of the gas
What property primarily determines the effect of temperature on the solubility of gas molecules? the kinetic energy of the gas the polarity of the gas the molecular weight of the gas the ionic strength of the gas the dipole strength of the solvent
atomic number = 85; atomic mass = 218
When Po emits a beta particle, it transforms into a new element. What are the atomic number and atomic mass of this new element? atomic number = 84; atomic mass = 219 atomic number = 86; atomic mass = 214 atomic number = 85; atomic mass = 218 atomic number = 82; atomic mass = 214
The boiling point of water is greatest where the water pressure is least, which is just below the surface.
Where is the boiling point of water the greatest: at the bottom of a pot of water or just below the surface? The boiling point of water is the same throughout the pot. The boiling point of water is is the greatest at the bottom where the density is greatest. The boiling point of water is greatest where the water pressure is least, which is just below the surface. The boiling point of water is greatest where the water pressure is greatest, which is at the bottom.
B
Which of the above liquids would most likely have the greatest capillary action? a b c d e
a
Which of the beams is due to a high energy electron? a b c all of the above none of the above
b
Which of the beams is due to an energetic non-visible light wave? a b c all of the above none of the above
when two elements with same charge are held together by electrostatic forces
Which of the following best describes ionic bonding? two atoms sharing a set of electrons two atoms exchanging a set of electrons one atom giving up some of its electrons to another atom when two elements with same charge are held together by electrostatic forces none of the above
High pressure saltwater is forced against a semipermeable membrane and fresh water comes out.
Which of the following describes reverse osmosis? High pressure saltwater is forced against a semipermeable membrane and fresh water comes out. Saltwater is chemically reacted with aluminum particles, which chemically binds to the chloride ions. The water is heated until it evaporates and condenses in a pure form. High pressure saltwater is reacted with aluminum, which absorbs the sodium ions in an oxidation reaction. none of the above
both C and D
Which of the following describes the reason for the following application of metals? Designer jewelry do not conduct heat well conduct electricity are shiny are strong but can be bent both C and D
Are strong but can be bent
Which of the following describes the reason for the following application of metals? Structural supports for buildings do not conduct heat well are shiny conduct electricity are strong but can be bent C and D
Na
Which of the following elements will most likely form an ion with a +1 charge? Na Mg Al Si Cl
Cl
Which of the following elements will most likely form an ion with a -1 charge? Na S Ne Mg Cl
Ar
Which of the following elements will most likely not form an ion at all? Na O Ar Mg Br
O2
Which of the following is NOT an ion? H+ Br- O2 Mg2+ NO3-
both B and D
Which of the following is a major disadvantage of nuclear-fission-based power plants? The reactors can be used to produce their own fuel. The byproducts of the fission process are radioactive and have very long half-lives. The amount of energy per kilogram of fuel is greater than any other fuel source. The power plants are complex and there are many safety requirements to prevent contamination of the environment. both B and D
O2-
Which of the following is a negative ion? Na+ Na O2- O all of the above
Adding a stream of radioisotopes to waste water to examine where pollution goes when it flows into the ocean
Which of the following might be considered a viable application of a radioactive tracer? adding a stream of radioisotopes to waste water to examine where pollution goes when it flows into the ocean placing radioactive sources around a room to trace the location of people as they move through the room embedding a radioactive plug in a valuable necklace so that its location can be determined using a Geiger counter all of the above none of the above
NH3
Which of the following molecules has the highest boiling point? BH3 NH3 CH4 SH2 All of the above have the same boiling point
H3C-CH3
Which of the following molecules would you expect to be the least attracted to a Na+ ion? H-F H3C-CH3 Cl2CH2 F- HO-
None of the above
Which of the following nuclear equations correctly describes alpha emission? 234Th90 = 234Pa91 + 0e-1 234Th90 = 234Ac89 + 0e-1 234Th90 = 235Pa91 + 0e-1 234Th90 = 0e-1 none of the above
suntan lotion
Which of the following provides the minimum amount of protection you need to block the following form of radiation? Alpha lead suit suntan lotion thick leather t-shirt none of the above
They all have the same concentration.
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.
one liter of water with 1 gram of sugar
Which of the following solutions is the most dilute? one liter of water with 1 gram of sugar one liter of water with 2 grams of sugar one liter of water with 5 grams of sugar one liter of water with 10 grams of sugar They all have the same volume.
The amount of energy released in the fission of large nuclei is very large.
Which of the following statements about fission is true? The amount of energy released in the fission of large nuclei is very large. The amount of energy released in the fusion of small nuclei is very large. Bombarding a nucleus with neutrons always leads to fission. The fragments of a fusion reaction are always the same size. none of the above
Your body contains a number of radioactive isotopes
Which of the following statements about radiation is true? Your body contains a number of radioactive isotopes. One rem is enough to kill approximately 50 percent of the average population. Radiation damages cells beyond repair. Radiation can make you glow in the dark.
The neutrons stabilize the nucleus by attracting protons and other neutrons.
Which of the following statements best describes the role of neutrons in the nucleus? The neutrons stabilize the nucleus by attracting protons and other neutrons. The neutrons stabilize the nucleus by forming bonds with other neutrons. The neutrons stabilize the nucleus by attracting protons. The neutrons stabilize the nucleus by balancing charge. The neutrons stabilize the nucleus by adding mass.
The nuclear forces are not as strong as the repulsive electrical forces between nucleons.
Which of the following statements best describes why a large nucleus is more likely to undergo radioactive decay? The nuclear forces are not as strong as the repulsive electrical forces between nucleons. The nuclear force between the nucleons are very strong and squeeze out other nucleons. The nucleon-nucleon attraction is stronger than the proton-proton repulsion. The proton-proton repulsion cannot overcome the nucleon attraction. All nuclei are equally likely to undergo radioactive decay.
The hydrogens of a water molecule have a partial negative charge.
Which of the following statements does not describe a property of water? You are made mostly of water. It is the only molecule that is found in all three phases (solid, liquid, gas. in large quantities on the planet. Water is very resistant to a change in temperature. Many of the properties of water are a direct consequence of the intermolecular attractions between water molecules. The hydrogens of a water molecule have a partial negative charge.
The valence electrons are only from s and p orbitals in the valence shell.
Which of the following statements is true? The valence electrons are only from s and p orbitals in the valence shell. All of the electrons in the valence shell are valence electrons. The valence electrons are always paired in the valence shell. Paired valence electrons are more unstable than unpaired valence electrons. Nonbonding electrons are not found in the valence shell.
The valence shell gives us the electron dot structure.
Which of the following statements is true? The valence shell is the innermost shell. The valence shell is usually the most unreactive shell. The valence shell gives us the electron dot structure. The electron dot structure is made up of each of the valence shells. none of the above
an atom with 11 protons and 12 electrons
Which of the following would be a negative ion with a single charge? an atom with 11 protons and 12 electrons an atom with 11 protons and 11 electrons an atom with 12 protons and 11 electrons an atom with 10 protons and 12 electrons none of the above
1 gram of steam at 100°C
Which of the following would cause the worst burn? 1 gram of steam at 100°C 1 gram of water at 100°C 1 gram of water at 50°C 1 gram of water at 0°C 1 gram of ice at 0°C
C6H14
Which of the following would have the smallest number of induced dipole-induced dipole interactions? C6H14 C8H18 C10H22 C12J26 Not enough information given
gold: fission; carbon: fusion
Which process would release energy from gold, fission or fusion? From carbon? gold: fission; carbon: fusion gold: fusion; carbon: fission gold: fission; carbon: fission gold: fusion; carbon: fusion
Metals can be efficiently extracted from them.
Why are metal ores so valuable? They are sources of naturally occurring gold. Metals can be efficiently extracted from them. They tend to occur in scenic mountainous regions. They hold many clues to Earth's natural history.
The fresh water acts to dissolve the blood cell wall.
Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals, burst when placed in fresh water? The dissolved ions provide a pressure that eventually bursts open the cell. More water molecules enter the cell than leave the cell. The fresh water acts to dissolve the blood cell wall. all of the above
The departing gas molecule takes some kinetic energy with it as it leaves the surface.
Why does evaporation cool a liquid? The departing gas molecule takes some kinetic energy with it as it leaves the surface. The overall heat decreases because the air cools. The average energy of the system increases because of the increased disorder in the new gas molecules. The gas molecules need to transfer their kinetic energy to the new slower gas molecule. none of the above
Much of the added energy is required to break hydrogen bonds.
Why does water have a high specific heat? Much of the added energy is required to break hydrogen bonds. Water is not very dense like metals and therefore doesn't conduct heat as readily. Much of the heat that is added to water is converted to kinetic energy. None of the energy is stored as potential energy. none of the above
Calcium chloride produces three ion particles while sodium chloride produces only two. Greater numbers of ions are more effective at decreasing the number of water molecules entering the solid phase.
Why is calcium chloride, CaCl2, more effective at melting ice than sodium chloride, NaCl? Calcium ions are both larger and more highly charged and thus more effective in breaking the ice crystal structure. Calcium ions are smaller than sodium ions and thus more able to get in the way of the water molecules attempting to form the solid state lattice. Calcium chloride produces three ion particles while sodium chloride produces only two. Greater numbers of ions are more effective at decreasing the number of water molecules entering the solid phase. Sodium ion is a natural water softener and therefore not as effective in inhibiting the formation of the solid state of water from the liquid.
The osmotic pressure exerted by fresh water is less.
Why is it significantly less costly to purify fresh water through reverse osmosis than to purify salt water through reverse osmosis? The osmotic pressure exerted by fresh water is less. The osmotic pressure exerted by fresh water is greater. For non-coastal regions, the salt water needs to be transported many miles from the oceans. The expense of reverse osmosis is not dependent upon the salt concentration in the water.
The continual release of energy by the freezing water keeps the temperature of the cellar from going below 0°C.
Why is it that in cold winters a tub of water placed in a farmer's canning cellar helps prevent canned food from freezing? As long as the water remains in the liquid phase, evaporation will give off heat to the cellar. If the canned goods are in the tub of water, molecular interactions will keep them from freezing. The cold in the cellar is consumed by freezing the water, not the canned goods. The continual release of energy by the freezing water keeps the temperature of the cellar from going below 0°C.
The hard ions in the water are more attracted to the carbonate ions -2 charge.
Why might sodium carbonate (washing soda, Na2CO3) be added to hard water to aid in cleaning? The hard ions in the water are more attracted to the carbonate ions -2 charge. The hard ions are dissolved by the added sodium ions. The soap gets softer due to the added ions. The ions solubilize the soap due to ion-ion intermolecular attraction, which improves the cleaning ability. none of the above
