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physics
conceptual physical science
Conceptual Physical Science 6th Edition Paul G. Hewitt, John A. Suchocki, Leslie A. Hewitt - Solutions
Why does a solution of a strong acid conduct electricity better than a solution of a weak acid having the same concentration?
When can a solution of a weak base be more corrosive than a solution of a strong base?
Is water a strong acid or a weak acid?
How many grams of water, H2O, and propene, C3H6, can be formed from the reaction of 6.0 g of 2-propanol, C3H8O?C3H8O → C3H6 + H2O
A 16-g sample of methane, CH4, is combined with a 16-g sample of molecular oxygen, O2, in a sealed container. Upon ignition, what is the maximum amount of carbon dioxide, CO2, that can be formed?CH4 + 2 O2 → CO2 + 2 H2O
Use the bond energies in Table 17.1 and the accounting format shown in Section 17.5 to determine whether these reactions are exothermic or endothermic:a.b.Table 17.1 Н Н N-N Н Н Н-н + Н Н +N, Н Н Н Н О—0+Н-—О + Н—О Н Н
Rank the following reaction profiles in order of increasing reaction speed. Reaction progress Reaction progress Reaction progress (c) (b) (a) - Energy - Energy Energy →
Rank the following in order of increasing entropy: a deck of playing cards (a) at 45°C, new and unshuffled sitting in a room at 25°C; (b) at 233°C, new and unshuffled sitting in a room at 25°C; (c) at 25°C, used and shuffled sitting in a room at 25°C.
Balance these equations:(a) ____ Fe(s) + ____ O2(g) → ____ Fe2O3(s)(b) ____ H2(g) + ____ N2(g) → ____ NH3(g)(c) ____ Cl2(g) + ____ KBr(aq) → ____ Br2(l) + ____ KCI(aq)(d) ____ CH4(g) + ____ O2(g) → ____ CO2(g) + ____ H2O(l)
Balance these equations:(a) ____ Fe(s) + ____ S(s) → ____ Fe2S3(s)(b) ____ P4(s) + ____ H2( g ) → ____ PH3( g)(c) ____ NO( g ) + ____ Cl2( g) → ____ NOCI( g)(d) ____ SiCl4(l ) + ____ Mg(s) → ____ Si(s) + ____ MgCl2(s )
Assume the illustrations above are two frames of a movie—one from before the reaction and the other from after the reaction. How many diatomic molecules are represented in this movie?
There is an excess of at least one of the reactant molecules. Which one? B
Which equation best describes this reaction?(a) 2 AB2 + 2 DCB3 + B2 → 2 DBA4 + 2 CA2(b) 2 AB2 + 2 CDA3 + B2 → 2 C2A4 + 2 DBA(c) 2 AB2 + 2 CDA3 + A2 → 2 DBA4 + 2 CA2(d) 2 BA2 + 2 DCA3 + A2 → 2 DBA4 + 2 CA2
The reactants shown schematically on the left represent methane, CH4, and water, H2O. Write out the full balanced chemical equation that is depicted.
The reactants shown schematically on the left represent iron oxide, Fe2O3 and carbon monoxide, CO. Write out the full balanced chemical equation that is depicted.
Which has more atoms: 17.031 grams of ammonia, NH3, or 72.922 grams of hydrogen chloride, HCl?
How many moles of molecules are there in each of the following?(a) 28 grams of nitrogen, N2(b) 32 grams of oxygen, O2(c) 32 grams of methane, CH4(d) 38 grams of fluorine, F2
How many moles of atoms are there in each of the following:(a) 28 grams of nitrogen, N2(b) 32 grams of oxygen, O2(c) 16 grams of methane, CH4(d) 38 grams of fluorine, F2
What is the mass of a water molecule in atomic mass units?
Is it possible to have a sample of oxygen that has a mass of 14 atomic mass units? Explain.
Which has the greater mass, 1.204 × 1024 molecules of molecular hydrogen or 1.204 × 1024 molecules of water?
How many grams of gallium are there in a 145-gram sample of gallium arenside, GaAs?
How many atoms of arsenic are there in a 145-gram sample of gallium arsenide, GaAs?
How is it possible for a jet airplane carrying 110 tons of jet fuel to emit 340 tons of carbon dioxide?
In the laboratory, endothermic reactions are usually preformed at elevated temperatures, whereas exothermic reactions are usually performed at lower temperatures. What are some possible reasons for this?
Does a refrigerator prevent or delay the spoilage of food? Explain.
Why does a glowing splint of wood burn only slowly in air, but burst into flames when placed in pure oxygen?
Give two reasons why heat is often added to chemical reactions performed in the laboratory?
Explain the connection between photosynthetic life on Earth and the ozone layer.
Does the ozone pollution from automobiles help alleviate the ozone hole over the South Pole? Defend your answer.
Chlorine is put into the atmosphere by volcanoes in the form of hydrogen chloride, HCl, but this form of chlorine does not remain in the atmosphere for very long. Why?
In the following reaction sequence for the catalytic formation of ozone from molecular oxygen, which chemical compound is the catalyst: nitrogen monoxide or nitrogen dioxide?O2 + 2 NO → NO22 NO2 → 2 NO + 2 O2 O + 2 O2 → O3
Are the chemical reactions that take place in a disposable battery exothermic or endothermic? What evidence supports your answer? Is the reaction that is going on in a rechargeable battery while it is recharging exothermic or endothermic?
Exothermic reactions are favored because they release heat to the environment. Would an exothermic reaction be more favored or less favored if it were carried out within a superheated chamber?
Estimate whether entropy increases or deceases with the following reaction. Use data from Table 17.1 to confirm your estimate.2 C(s) + 3 H2(g) → C2H6(g)Table 17.1 Bond Energy (kJ/mole) Bond Energy (kJ/mole) Bond Bond Н-Н 436 159 Н-С 414 138 Cl-CI 389 Н—N 243 803 Н—О 464 C=0 Н-—F 569
According to the second law of thermodynamics, exothermic reactions, such as the burning of wood, are favored because they result in the dispersal of energy. Wood, however, will not spontaneously burn even when exposed to pure oxygen, O2. Why not?
What role does entropy play in chemical reactions?
Under what conditions will a hot pie not lose heat to its surroundings?
As the Sun shines on a snow-capped mountain, much of the snow sublimes instead of melting. How is this favored by entropy?
Wild plants readily grow “all by themselves,” yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for there to be this decrease in entropy for a process that occurs all by itself?
Show that the formula mass of 2-propanol, C3H8O, is 60 amu, that the formula mass of propene, C3H6, is 42 amu, and that the formula mass of water, H2O, is 18 amu.
Small samples of oxygen gas needed in the laboratory can be generated by a number of simple chemical reactions, such as2 KClO3(s) → 2 KCl(s) + 3 O2(g)What mass of oxygen (in grams) is produced when 122.55 g of KClO3 (formula mass = 122.55 amu) takes part in this reaction?
Small samples of oxygen gas needed in the laboratory can be generated by a number of simple chemical reactions, such as2 KClO3(s) → 2 KCl(s) + 3 O2(g)According to this balanced chemical equation, how many moles of oxygen gas are produced from the reaction of 2 moles of KClO3 solid?
Show that 1 mole of KClO3 contains 122.55 g.
How many gold atoms are there in a 5.00-g sample of pure gold, Au (197 amu)?
Show that there are 1.0 × 1022 carbon atoms in a 1-carat pure diamond that has a mass of 0.20 g.
Add lukewarm water to two plastic cups. (Do not use insulating Styrofoam cups.) Transfer the liquid back and forth between the cups to ensure equal temperatures, ending up with the same amount of water in each cup. Add several tablespoons of table salt to one cup and stir. What happens to the
Hold some room-temperature water in the cupped palm of your hand over a sink. Pour an equal amount of room-temperature rubbing alcohol into the water. Is this mixing an exothermic or endothermic process? What’s going on at the molecular level?
An Alka-Seltzer antacid tablet reacts vigorously with water. But how does this tablet react to a solution of half water and half corn syrup? Propose an explanation involving the relationship between reaction speed and the frequency of molecular collisions.
If you ever have the opportunity to play with an electric train set, be sure to smell the engine car after it has been operating. You will note a slight “electric smell.” This is the smell of ozone gas, which is created as the oxygen in the air is zapped with electrical sparks. Why is this
Why are exothermic reactions self-sustaining?
What is always increasing?
As energy disperses, where does it go?
What is absorbed by an endothermic reaction?
What is released by an exothermic reaction?
If it takes 436 kJ to break a bond, how many kilo-joules are released when the same bond is formed?
Why are catalysts so important to our economy?
What net effect does a chemical reaction have on a catalyst?
What does a catalyst do to the energy of activation for a reaction?
What catalyst is effective in the destruction of atmospheric ozone, O3?
What term is used to describe the minimum amount of energy required in order for a reaction to proceed?
Which reactant molecules are the first to pass over the energy barrier?
What generally happens to the rate of a chemical reaction with increasing temperature?
Why don’t all collisions between reactant molecules lead to product formation?
Why is saying you have 1 mole of water molecules the same as saying you have 6.02 × 1023 water molecules?
How many molecules of water are there in 18 g of water?
How many moles of water are there in 18 g of water?
If you had 1 mole of marbles, how many marbles would you have? How about 2 moles?
What is the formula mass of nitrogen monoxide, NO, in atomic mass units?
Why is it important never to change a subscript in a chemical formula when balancing a chemical equation?
Why is it important that a chemical equation be balanced?
How many oxygen atoms are indicated on the right side of this balanced chemical equation?4 Cr(s) + 3 O2(g) → 2Cr2O3( g)
What is the purpose of coefficients in a chemical equation?
A scum forms on the surface of boiling hard water. What is this scum? Why does it form? And why do hot water heaters lose their efficiency sooner in households with hard water?
Fatty acid molecules can also align to form a bilipid layer that extends in three dimensions. Shown below is a cross section of this structure. This is similar to the micelle shown in Figure 16.23, though notably different because it contains an inner compartment of water. What is this structure
How is it that water and soap are attracted to each other not only by ion–dipole attraction but also by dipole–induced dipole attraction?
Calcium and magnesium ions are more attracted to sodium carbonate than to soap. Why?
Phosphate ions, PO43-, were once added to detergents to assist in cleaning. What function did they serve? These ions are no longer added to detergents because they cause excessive growth of algae in aquatic habitats receiving the wastewater. What chemical has replaced them?
Cells at the top of a tree have a higher concentration of sugars than cells at the bottom. How might this fact facilitate the movement of water upward from the roots of the tree?
Why is distilling water so relatively expensive?
What reverses with reverse osmosis?
Why is it significantly less costly to purify fresh water through reverse osmosis than to purify salt water through reverse osmosis?
Some people fear drinking distilled water because they have heard that it leaches minerals from the body. Using your knowledge of chemistry, explain why these fears have no basis and why distilled water is in fact very good for drinking.
Many homeowners get their drinking water piped up from wells dug into their property. Sometimes this well water smells bad because of trace quantities of the gaseous compound hydrogen sulfide, H2S. How might this odor be removed from water already taken from the tap?
Is the decomposition of food by bacteria in our digestive systems aerobic or anaerobic? What evidence supports your answer? How do composting toilets work to remove the bad smells of human waste?
Where does most of the solid mass of raw sewage end up after being collected at a treatment facility?
Why is flushing a toilet with clean water from a municipal supply about as wasteful as flushing it with bottled water?
Why do nonpolar molecules have a difficult time passing through the bilipid layer? How about polar molecules? Н.о НО Na+ Н,О Bilipid layer Н.О НО Но Fatty acid
Which of these boxes best represents a suspension?
How many sugar molecules are there in a 2 M sugar solution?
Would you expect to find more dissolved oxygen in ocean water around the northern latitudes or in ocean water close to the equator? Why?
Why can 500 mL of fresh water absorb more gaseous carbon dioxide than 500 mL of sugar water at the same temperature?
Two plastic bottles of fresh seltzer water are opened. Three-fourths of the first bottle are poured out for drinking, while only one-fourth of the second bottle is poured. Both bottles are then tightly resealed. The next day, when they are both reopened, one is less fizzy. Which one? Why?
Some bottled water is now advertised as containing extra quantities of “Vitamin O,” which is a marketing gimmick for selling oxygen, O2. Might this bottled water actually contain extra quantities of oxygen, O2? How much more than one might find in regular bottled water? How might the amount of
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?
Why is rain or snow called precipitation?
At 10°C, which is more concentrated: a saturated solution of sodium nitrate, NaNO3, or a saturated solution of sodium chloride, NaCl? (See Figure 16.20.) NaNO3 180 160 140 120 LicI 100 80 60 KCI 40 NaCI 20 20 40 80 60 100 Solubility (grams of solute in 100 ml of water)
Account for the observation that ethanol, C2H5OH, dissolves readily in water, but dimethyl ether, CH3OCH3,which has the same number and kinds of atoms, does not. нн н Н. Н Н Н-С—С-О нн Ethanol Н Dimethyl ether Н
The air a scuba diver breathes is pressurized to counteract the pressure exerted by the water surrounding the diver’s body. Breathing the high-pressure air causes excessive amounts of nitrogen to dissolve in body fluids, especially the blood. If a diver ascends to the surface too rapidly, the
If nitrogen, N2, were pumped into your lungs at high pressure, what would happen to its solubility in your blood?
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