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sciences
the physical universe
The Physical Universe 16th edition Konrad B Krauskopf, Arthur Beiser - Solutions
The earth bulges slightly at the equator and is flattened at the poles becausea. It spins on its axisb. It revolves around the sunc. Of the sun’s gravitational pulld. Of the moon’s gravitational pull
Compare the ptolemaic and copernican explanations for(a) The rising and setting of the sun;(b) The eastward drift of the sun relative to the stars that takes a year for a complete circuit;(c) The eastward drift of the moon relative to the stars that takes about 4 weeks for a complete circuit.
According to Kepler’s third law, the time needed for a planet to complete an orbit around the suna. Is the same for all the planetsb. Depends on the planet’s sizec. Depends on the planet’s distance from the sund. Depends on how fast the planet spins on its axis
What is the basic difference between the ptolemaic and copernican models? Why is the ptolemaic model considered incorrect?
Kepler modified the copernican system by showing that the planetary orbits area. Ellipsesb. Circlesc. Combinations of circles forming looped orbitsd. The same distance apart from one another
From observations of the moon, why would you conclude that it is a relatively small body revolving around the earth rather than another planet revolving around the sun?
What must be your location if the stars move across the sky in circles centered directly overhead?
Which of the following is no longer considered valid?a. the ptolemaic systemb. the copernican systemc. Kepler’s laws of planetary motiond. Newton’s law of gravity
You are lost in the northern hemisphere in the middle of nowhere on a clear night. How could you tell the direction of north by looking at the sky?
The object in the sky that apparently moves least in the course of time isa. Polarisb. Venusc. The sund. The moon
According to the physicist Richard Feynman, “Science is the culture of doubt.” Does this mean that science is an unreliable guide to the natural world?
A hypothesis isa. A new scientific ideab. A scientific idea that has been confirmed by further experiment and observationc. A scientific idea that has been discarded because it disagrees with further experiment and observationd. A group of linked scientific ideas
What is the difference between a hypothesis and a law? Between a law and a theory?
The scientific method isa. A continuing processb. A way to arrive at ultimate truthc. A laboratory techniqued. Based on accepted laws and theories
What role does “common sense” play in the scientific method?
The brakes of a car are applied to give it an acceleration of –3 m/s2. The car comes to a stop in 5 s. What was its speed when the brakes were applied?
The acceleration of a certain moving object is constant in magnitude and direction. Must the path of the object be a straight line? If not, give an example.
Two tugboats are towing a ship. Each exerts a horizontal force of 5 tons and the angle between their towropes is 908. What net force is exerted on the ship?
A man is rowing at 8 km/h in a river 1.5 km wide in which the current is 5 km/h.(a) In what direction should he head in order to get across the river in the shortest possible time? (b) How much time will he take if he goes in this direction? (c) How far downstream will the boat have gone
Three forces, each of 10 lb, act on the same object. What is the maximum total force they can exert on the object?The minimum total force?
A snake is slithering toward you at 1.5 m/s. If you start walking when it is 5 m away, how fast must you go so that the snake will not overtake you when you have gone 100 m?
The starter of a race stands at one end of a line of runners. What is the difference in time between the arrival of the sound of his pistol at the nearest runner and at the most distant runner 10 m farther away? (In a sprint, 0.01 s can mean the difference between winning and coming in second.)
How do leap years fit into the ptolemaic system? Into the copernican system?
Use the proper number of significant figures to express the values ofa. 47.2 + 9.11 - 14b. (3.58 × 102)(2.1 × 103)c. 7.8 x 103 3.21 x 10-2 + 5.4 × 104
The diameter of an atom is roughly 104 times the diameter of its nucleus. If the nucleus of an atom were 1 mm across, how many feet across would the atom be?
When chlorine gas is bubbled through a solution of sodium hydroxide (NaOH), the products are sodium hypochlorite (NaOCl), sodium chloride, and another substance. What is the other substance? Give the equation of the process.
Butane (C4H10) burns in air to give carbon dioxide and water.
Heating magnesium nitrate gives magnesium oxide, nitrogen dioxide, and oxygen.
What kind of solid is ice? Why does ice float when nearly all other solids sink when they freeze?
You are given two solids that look nearly alike, one of which is held together by ionic bonds and the other by van der Waals forces. How could you tell them apart?
From which class of solids would you expect electrons to be liberated most readily by the photoelectric effect when light is shined on a sample?
Lithium atoms, like hydrogen atoms, have only a single electron in their outer shells, yet lithium atoms do not join together to form Li2 molecules the way hydrogen atoms form H2 molecules. Instead, lithium is a metal with each atom part of a crystal structure. Can you think of the reason for this
What ions would you expect to find in the crystal structures of MgO and K2S?
Why is the solubility of one gas in another unlimited?
Ordinary tap water tastes different after it has been boiled. Can you think of the reason why?
What is the difference between a molecular ion and a polar molecule?
You have a solution that contains Ca2+ ions and another that contains Na+ ions. How would adding a solution that contains CO 2-3 ionss enable you to tell which is which?
What is the easiest way to distinguish between a solution that contains Cu2+ ions from one that contains Ca2+ ions?
Seawater freezes at a lower temperature than pure water because of the salts dissolved in it. How does the boiling point of seawater compare with that of pure water?
What are the two chief ions found in seawater?
The pesticide DDT concentrates in the fat of animals and tends to remain in the soil despite heavy rain that washes away other contaminants. What do these observations tell you about the nature of the DDT molecule?
Which of the following are weak acids? Hydrochloric acid, nitric acid, acetic acid, sulfuric acid, citric acid.
Even though ammonia is not a base because its molecules do not contain OH groups, its solution in water is basic. Why?
In an acidic solution, why is the OH- concentration lower than it is in pure water?
When a salt that contains the negative ion of a weak acid is dissolved in water, the solution is basic. For example, a solution of sodium acetate (the corresponding acid is acetic acid) is basic. Why?
What salt is formed when a solution of calcium hydroxide is neutralized by phosphoric acid, H3PO4? Give the equation of the process.
What salt is formed when a solution of sodium hydroxide is neutralized by sulfuric acid? Give the equation of the process.
Give the equation of the reaction described below: Johnny, finding life a bore, Drank some H2SO4. Johnny’s father, an MD, Gave him CaCO3.Now he’s neutralized, it’s true, But he’s full of CO2.
Boric acid (H3BO3) is a very weak acid. What would happen if solutions of Na3BO3 (sodium borate) and HCl were mixed?
From the fact that H2S is a weak acid, would you predict that a solution of Na2S would be acidic, basic, or neutral? Why?
(a) What is the formula of ozone? (b) Ozone in the atmosphere is both harmful to and essential for our health. Explain.
For a given amount of energy to be used for its propulsion, a spacecraft must have much larger tanks than an airplane. Why?
When hydrogen is burned in oxygen, water is formed according to the reaction 2H2 + O2 → 2H2O. How many moles of H2 and how many of O2 are needed to produce 3 mol of H2O?
How many moles of atomic oxygen are present in 1 mol of Ca3(PO4)2?
How many moles of Al are needed to react with each mole of CuSO4 in the reaction 2Al + 3CuSO4 → 3Cu + Al2(SO4)3?
Find the mass of 5 mol of ethylene, C2H4. How many carbon atoms are present in the sample?
Find the mass of 1.6 mol of magnesium, Mg. How many atoms are present in such a sample?
Find the mass of 30 mol of sulfuric acid, H2SO4.
How many moles of lead nitrate are present in 100 g of lead nitrate, Pb(NO3)2?
When potassium chlorate, KClO3, is heated, it decomposes into potassium chloride and oxygen in the reaction 2KClO3 2KCl + 3O2. How much oxygen is liberated when 50 g of potassium chlorate is heated?
How much CO2 is produced when 100 g of butane (C4H10) is burned in the reaction 2C4H10 + 13O2 8CO2 + 10H2O?
What is the origin of the energy liberated in an exothermic reaction?
From the observation that the slaking of lime [addition of water to CaO to form Ca(OH)2] gives out heat, would you conclude that the following reaction is endothermic or exothermic?Ca(OH )2 → CaO + H2O
When carbon in the form of diamond is burned to produce CO2, more heat is given off than when carbon in the form of graphite is burned. What form of carbon is more stable under ordinary conditions? What bearing does this conclusion have on the origin of diamonds?
Do ions in solution need activation energy to react with one another? If not, why not?
Hydrogen peroxide, H2O2, decomposes into water and oxygen, O2.(a) Write the equation of the process. (b) The total energies of all the bonds in H2O2 and in H2O are, respectively, 1065 and 920 kJ/mol and the bond energy in O2 is 494 kJ/mol. Is the process endothermic or exothermic?(c) What is
Why does an increase in temperature increase the rate of exothermic as well as endothermic reactions?
Suggest three ways to increase the rate at which zinc dissolves in sulfuric acid.
Under ordinary circumstances coal burns slowly, but the fine coal dust in mines sometimes burns so rapidly as to cause an explosion. Explain the difference in rates.Would you expect the danger from spontaneous combustion to be greater in a coal pile containing principally large chunks or in one
The solubility of a gas in a liquid decreases with increasing temperature. From this observation and what you know of how a change in temperature can affect an equilibrium, would you expect that dissolving a gas in a liquid is an exothermic or an endothermic process?
To what extent does the time needed for a strong acid to neutralize a strong base in solution depend on temperature?
The reaction 2SO2 + O2 2SO3 is exothermic. (a) How will a rise in temperature affect the yield of SO3 in an equilibrium mixture of the three gases?(b) Will an increase in pressure raise or lower the yield?(c) In what possible way can the speed of the reaction be increased at moderate
Hydrogen sulfide gas dissolves in water and dissociates very slightly: H2S ⇌ 2H+ + S2-. How would the acidity of the solution be affected by a. Increasing the pressure of H2S?b. Raising the temperature?c. Adding a solution of KOH? d. Adding a solution of silver nitrate? (Silver sulfide,
A displacement reaction is an oxidation-reduction reaction in which one element displaces another from solution. In each of the following displacement reactions identify the element that is oxidized and the element that is reduced: Zn + Cu2+ Fe + 2H* Cl, + 2Br- Zn²+ + Cu Fe2+ + H2 2CI+ Br, 111
When magnesium is placed in an acid solution, hydrogen gas is given off. Is magnesium or hydrogen the better reducing agent?
In the refining of iron the iron(III) oxide, Fe2O3, in iron ore is reduced by carbon (in the form of coke) to yield metallic iron and carbon dioxide. Write the balanced equation of the process.
When an electric current is passed through a solution of copper chloride, what substance is liberated at the positive electrode? At the negative electrode?
In what basic way is a fuel cell different from a dry cell or a storage battery?
In what ways do organic compounds, as a class, differ from inorganic compounds?
How can the different alkanes in petroleum be separated? What property of the alkanes makes this procedure possible?
Why are structural formulas more important in organic chemistry than in inorganic chemistry?
Distinguish between unsaturated and saturated hydrocarbons, giving examples of each.
What kind of carbon-carbon bonds are found in alkane molecules?
In general, how do the reactivities of hydrocarbon molecules that contain only single bonds compare with the reactivities of hydrocarbon molecules that contain double or triple bonds as well?
Why does this structural formula not represent an actual molecule? Н Н —С — С | | Н Н Н
In which of the compounds C2H2, C2H4, and C4H10 are the carbon-carbon bonds single, in which are they double, and in which are they triple?
Is it possible for a molecule with the formula C2H3 to exist? If not, why not?
Why are all aromatic compounds unsaturated?
Ethanol can be used as an automotive fuel either by itself or added to gasoline. Give the equation for the combustion of ethanol.
To what class of organic compounds does the compound belong whose structure is shown below? Н C-C-C -C НО ОН ОН
What have the compounds in each of these pairs in common? How could you distinguish one from the other?(a) CH3COOH and CH3OH(b) C2H5OH and H2O
Which of the following (a) dissolve in water,(b) are acids, (c) react with ethyl alcohol to give esters, (d) react with acetic acid to give esters?C2H5COOH C3H8C2H4 C2H5OHHCl C3H5(OH)3
Why do you think the compound whose structure is shown below is called dimethyl ether? Н Н | Н —С —0— С — Н Н Н
Teflon is inert, tough, and can tolerate high temperatures because the bonds between carbon and fluorine in its structure are extremely strong. What does this suggest about the chemical activity of fluorine?
What are the products of the oxidation of glucose? Is the process endothermic or exothermic?
The ultimate source of the energy in food is the energy liberated when hydrogen is converted to helium in thermonuclear reactions in the sun. Trace this energy from the sun to the food you eat.
Why do plants need nitrogen? Why can they not use nitrogen from the air? Where do nitrogen compounds in the soil come from?
To which class of organic compounds do most of the constituents of living cells belong?
If the earth’s axis were tilted more than its present 23.5°, in what way, if any, would the seasons be affected?
(a) At what times of year are the periods of daylight and darkness the same everywhere on the earth? What are these times called? (b) Where is the noon sun directly overhead at these times?
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