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All Textbook Solutions for Chemistry In Focus

A chemist observes the behavior of a gas by filling a balloon and measuring its volume at different temperatures. After making many measurements, he concludes that the volume of a gas always increases with increasing temperature. The chemist's conclusion is best classified as an: a. observation b. law c. theory Classifying Matter Determine whether each of the following is a pure element, a compound, or a mixture. If it is a mixture, classify it as homogeneous or heterogeneous: a. pure salt b. helium gas c. chicken noodle soup d. coffee A cup of coffee is an example of: a. a liquid pure substance b. a gaseous mixture c. a solid pure substance d. a liquid mixture e. a solid mixture Water is put on the stove and heated with a natural gas burner. After some time, the water begins to bubble, and steam is given off. What kind of change has occurred? a. physical b. chemical c. no change has occurred The Conservation of Mass A match is weighed and then burned. The ashes are found to weigh much less. How can this be consistent with the conservation of mass?Constant Composition of Compounds Two samples of sugar are decomposed into their constituent elements. One sample of sugar produces 18.0 g carbon, 3.0 g hydrogen, and 24.0 g oxygen; the other sample produces 24.0 g carbon, 4.0 g hydrogen, and 32.0 g oxygen. Find the ratio of carbon to hydrogen and the ratio of oxygen to hydrogen for each of the samples, and show they are consistent with the law of constant composition.4SC What is meant by the statement Macroscopic observations have molecular causes? Give two examples.Why should nonscience majors study science?3E Define chemistry.5E 6E How are science and art similar? How are they different?What is different about the Greek philosophers approach to scientific knowledge and the approach taken today?Match each of the people in column A with their contribution to scientific knowledge in column B. A B Galileo conservation of mass Democritus all things are water John Dalton inquisition Andreas Vesalius the nuclear atom Empedocles Sun-centered universe Joseph Proust human anatomy Copernicus the atomic theory Ernest Rutherford constant composition Thales atomos Antoine Lavoisier four basic elements Robert Boyle criticized idea of four Greek elements What were the two main pursuits of alchemy? What were the contributions of alchemy to modern chemistry?11E What is the difference between an element and a compound? Give two examples of each.What is the difference between a pure substance and a mixture? Give two examples of each.What is the difference between a homogeneous mixture and a heterogeneous mixture? Give one example of each.Explain the differences among a solid, a liquid, and a gas, based on the atoms or molecules that compose them.Match each term in the left column with three terms from the right column. You may use terms in the right column more than once. solid incompressible liquid compressible gas fixed volume fixed shape variable shape variable volume What is the atomic theory?Describe Rutherfords gold foil experiment.Describe the structure of the atom as explained by Rutherford. How was this picture consistent with the outcome of his gold foil experiment?What are black holes, and how does their existence relate to the internal structure of atoms?Classify each of the following as an observation or a law: a. When water boils, small bubbles form in the liquid and rise rapidly to the surface. b. Two grams of hydrogen combine with 16 grams of oxygen to form 18 grams of water. c. Chlorine and sodium readily combine in a chemical reaction that emits much heat and light. d. The properties of elements vary periodically with the mass of their atoms.Classify each of the following as a law or a theory: a. In a chemical reaction, energy is neither created nor destroyed. b. All matter is composed of atoms. c. When the temperature of a gas is increased, the volume of the gas increases. d. Gases are composed of particles in constant motion.To the best of your knowledge, classify each of the following as an element, a compound, or a mixture. If it is a mixture, classify it as homogeneous or heterogeneous. a. silver coin b. air c. coffee d. soil To the best of your knowledge, classify each of the following as an element, a compound, or a mixture. If it is a mixture, classify it as homogeneous or heterogeneous. a. pure water b. copper wire c. graphite in a pencil d. oil and water Which substance is a liquid mixture? a. lemonade b. brass c. air d. wood Which substance is a solid? a. the helium in a balloon b. dry ice c. vegetable oil d. shampoo Classify each of the following properties as chemical or physical: a. the tendency of dry ice to vaporize directly from a solid to a gas b. the flammability of LP gas (the kind you put your outdoor grill) c. the boiling point of water d. the smell of cologne Classify each of the following properties as chemical or physical: a. the tendency of silver to tarnish b. the flammability of alcohol c. the volatility (ease of vaporization) of alcohol d. the malleability (ability to be pounded into sheets) of metal Classify each of the following changes as physical or chemical: a. the crushing of salt b. the rusting of iron c. the burning of natural gas in a stove d. the vaporization of gasoline Classify each of the following changes as physical or chemical: a. the burning of butane in a lighter b. the freezing of water c. the bending of a copper rod d. the fading of a brightly colored cloth upon excessive exposure to sunlight The burning of gasoline in automobile engines is a chemical reaction. In light of the law of conservation of mass, explain what happens to the gasoline in your cars tank as you drive.A campfire is a chemical reaction involving wood and oxygen from the air. In light of the law of conservation of mass, explain what happens to the mass of the wood during the reaction. How is mass conserved if the wood disappears?33E 34E A chemist combines 22 grams of sodium with 28 grams of chlorine. A spectacular reaction occurs and produces sodium chloride. After the reaction, the chemist finds that all the chlorine was used up by the reaction, but 4 grams of sodium remained. How many grams of sodium chloride were formed?A chemist combines 6 grams of hydrogen with 52 grams of oxygen in an explosive reaction that forms water as its sole product. All of the hydrogen reacts, but 4 grams of oxygen remain. How many grams of water are formed?Several samples of carbon dioxide are obtained and decomposed into carbon and oxygen. The masses of the carbon and oxygen are then weighed, and the results are tabulated as shown here. One of these results does not follow the law of constant composition and is therefore wrong. Which one? a. 12 grams of carbon and 32 grams of oxygen b. 4.0 grams of carbon and 16 grams of oxygen c. 1.5 grams of carbon and 4.0 grams of oxygen d. 22.3 grams of carbon and 59.4 grams of oxygen Several samples of methane gas, the primary component of natural gas, are decomposed into carbon and hydrogen. The masses of the carbon and hydrogen are then weighed, and the results are tabulated as shown here. Which of these does not follow the law of constant composition? a. 4.0 grams hydrogen and 12.0 grams carbon b. 1.5 grams hydrogen and 4.5 grams carbon c. 7.0 grams hydrogen and 17.0 grams carbon d. 10 grams hydrogen and 30 grams carbon According to Rutherfords model of the atom, how many electrons would be found in each of the following atoms? a. sodium, which has 11 protons in its nucleus b. calcium, which has 20 protons in its nucleus According to Rutherfords model of the atom, how many electrons would be found in each of the following atoms? a. fluorine, which has 9 protons in its nucleus b. sulfur, which has 16 protons in its nucleus When water boils, small bubbles form in the liquid. Come up with a hypothesis to explain what is happening during the process. How might you test this hypothesis?42E 43E 44E 45E The nuclei of a limited number of atoms are investigated to determine the number of protons and neutrons in each. The following table summarizes the results: helium 2 protons, 2 neutrons carbon 6 protons, 6 neutrons nitrogen 7 protons, 7 neutrons a. Form a scientific law based on these limited measurements. b. What other measurements could be carried out to further confirm this law? c. Devise a theory that would explain your law. d. How would the following results affect your theory and your law? uranium 92 protons, 143 neutrons chromium 24 protons, 28 neutrons 47E Based on the molecular views shown for each of the following substances, classify them as an element, a compound, a homogeneous mixture, or a heterogeneous mixture:Read The Molecular Revolution" box in this chapter on seeing atoms. How is the technology explained in the box a confirmation of the atomic theory? Does the technology "prove the atomic theory?The volume of a liquid can be measured with a piece of laboratory glass ware called a graduated cylinder. If a particular volume measurement using a graduated cylinder is reported as 23.4mL, what is the degree of uncertainty associated with the measurement? a.1mLb.0.1mLc.0.01mLd.0.001mL Scientific Notation Express the number 0.0000023 in scientific notation.2SC 3SC Converting Between Units Convert 34.0 cm to inches.2.3YT Extracting Information from Graphical Data The following graph shows the average SAT score for incoming students at up- and-coming University. a. What is the total increase in SAT score over this period? b. What is the average yearly increase in SAT score over this period? c. What is the total percentage increase in SAT score over this period? d. What is the average yearly percentage increase over this period?Solving Word Problems Aswimmerwantstoswim1.50mieachdayinapoolthatis60.0feet(ft)long.Howmanypoollengthsmustsheswim?(1.00miles=5280feet)Solving Word Problems Involving Units Raised to a Power How many cubic inches are there in 1.00yd3?2.7YT 2.8YT Without doing any calculations, determine whether substance A with a density of 1.0g/cm3 is more or less dense than substance B with a density of 1.0kg/m3. a.substanceAb.substanceB 1E 2E 3E What is the difference between reporting the quantity nine inches as 9 inches and 9.00 inches?5E 6E 7E 8E 9E What is a conversion factor? Give two examples of conversion factors and explain what units they convert from and what units they convert to.11E Identify the decimal part, the exponential part, and the exponent of the number 9.66105.What is density? Give two examples of possible units for density.Since oil floats on water, what can you say about the relative densities of oil and water?Express each of the following in scientific notation: a. 0.000851 g b. 38,041,430 (population of California) c. 299,790,000 m/s (speed of light) d. 313,914,040 (U.S. population)Express each of the following numbers in scientific notation: a. 19,570,261 (population of New York state) b. 7,190,900,000 (world population) c. 0.00000000007461 m (length of a hydrogen- hydrogen chemical bond) d. 0.000015 m (diameter of a human hair)Express each of the following in decimal notation: a. 149106 km (average distance between Earth and the Sun) b. 7.91011 m (radius of a hydrogen atom) c. 4.54109 yr (age of Earth) d. 6.4106 m (radius of Earth)Express each of the following in decimal notation: a. 6.0221023 (number of carbon atoms in 12.01 grams of carbon) b. 3.00108 m/s (speed of light) c. 450109 m (wavelength of blue light) d. 13.7109 yr (approximate age of the universe)The circumference of Earth at the equator is 40,075 km. Convert this distance into each of the following units: a. meters b. miles c. feet The distance from New York to Los Angeles is 2777 miles. Convert this distance into each of the following units: a. kilometers b. meters c. feet A can of soda contains 12 fluid ounces. What is this volume in mL? (128fluidounces=3.785L)A laboratory beaker can hold 150mL. How many fluid ounces can it hold? (128fluidounces=3.785L)A car has a fuel efficiency of 27 miles per gallon. What is its efficiency in kilometers per gallon?A European rental car can travel 17 km on a liter of fuel. How many miles can it travel on a liter of fuel?Perform each of the following conversions within the metric system: 4332 mm to m 1.76 kg to g 4619 mg to kg 0.0117 L to mL Perform each of the following conversions within the metric system: a.2319cmtomb.4912.5gtokgc.23.1cmtommd.561mLtoL 27E Perform the following conversions between the metric and English systems: 4.92 in. to mm 8779 yd to km 87 ft to m 3.8 in to cm A pond has a surface area of 1552m2. Convert this quantity into each of the following units: a.ft2b.km2c.dm2 An orange has a volume of 54cm3. Convert this quantity into each of the following units: mm3 in.3 dm3 31E 32E A runner runs at a pace of 8.5 minutes per mile. She wants to run 10.0km. For how long should she run?A driver drives an average speed of 58 miles per hour. How long will it take the driver to reach a destination that is 155 km away?A sports utility vehicle gets 12 miles per gallon of gas. Calculate this quantity in miles per liter and kilometers per liter.A hybrid electric vehicle (HEV) is a car with both a gasoline-powered engine and an electric motor. Some HEVs achieve mileage ratings as high as 75 miles per gallon of gas. Calculate this quantity in miles per liter and kilometers per liter.The following graph shows the concentration of an atmospheric pollutant, carbon monoxide, for the period 1990-2015. As shown by this graph, carbon monoxide levels have decreased in the atmosphere because of mandatory reductions legislated by the Clean Air Act. a. What is the total decrease in carbon monoxide over this period? b. What is the average yearly decrease in carbon monoxide over this period? c. What is the total percentage decrease in carbon monoxide over this period? d. What is the average yearly percentage decrease in carbon monoxide over this period?The following graph shows the historical concentration of atmospheric carbon dioxide in the atmosphere. Carbon dioxide concentrations began increasing in the 1800s as humans started to rely on combustion for energy (carbon dioxide is a product of combustion). The increase in atmospheric carbon dioxide is linked to the increases in global temperatures known as global warming. a. What is the total increase in carbon dioxide between 1950 and 2007? b. What is the average yearly increase in carbon dioxide over this period? c. What is the total percentage increase in carbon dioxide over this period? d. What is the average yearly percentage increase in carbon dioxide over this period?A 28.4-cm3 sample of titanium has a mass of 127.8g. Calculate the density of titanium in g/cm3.A 1.5-cm3 sample of silicon has a mass of 3.5 g. Calculate the density of silicon in g/cm3.A 5.00-L sample of pure glycerol has a mass of 6.30103 g. What is the density of glycerol in g/cm3?A 3.80-mL sample of mercury has a mass of 51.4g. What is the density of mercury in g/cm3?Ethylene glycol (antifreeze) has a density of 1.11g/cm3. a. What is the mass in g of 38.5mL of this liquid? b. What is the volume in L of 3.5kg of this liquid?A thief plans to steal a bar of gold from a womans purse and replace it with a bag of sand. Assume that the volumes of the gold and the sand are 350 mL each and that the density of sand is 3.00g/cm3. a. Calculate the mass of each object. b. Would the woman notice a difference in the weight of her purse?45E A proton has a radius of approximately 110-13 cm and a mass of 1.71024 g. a. Determine the density of a proton. For a sphere, V=(4/3)r3;1cm3=1mL;=3.14. b. By assuming that black holes have the same density as protons, determine the mass (in kilograms) of a black hole and the size of a sand particle. A typical sand particle has a radius of 1104 m.What did Einstein mean when he said, The most incomprehensible thing about the world is that it is comprehensible?48E 49E 50E 51E Consider each of the following balances. Which one is the most precise? Which one is the least? How much uncertainty is associated with each balance?Each of the following coins is photographed to scale. Measure each using a metric ruler (in cm) and record the diameter to the precision reflected in the ruler. Make a simple graph of the value of the coin (x-axis) and the diameter of the coin (y-axis). Is there any correlation between these two quantities? Which coin does not fit the general trend?Obtain an outdoor thermometer and record the temperature every day for one month. Be sure to record the temperature at the same time every day. Make a graph of your temperature beginning with day 1 and ending at day 30. Are there any trends in the temperature? If there is a trend, calculate the average daily change.Determining the Number of Protons and Electrons in an Ion How many protons and electrons are in the Mg2+ ion?3.2YT Determining Protons, Neutrons, and Electrons How many protons, neutrons, and electrons are in the following ion? 1735Cl-Calculating Atomic Mass Magnesium has three naturally occurring isotopes with masses 23.99,24.99,and25.98amu and natural abundances 78.99,10.00,and11.01%. Calculate the atomic mass of magnesium.The Mole Concept A diamond, which is pure carbon, contains 0.020 mol of carbon. What is the mass, in grams, of the diamond?The Mole Concept II Calculate the number of atoms in a pure gold ring weighing 17 g.Your friend tells you about an article that he read in a tabloid that reported the discovery of a new form of carbon containing eight protons in the nucleus of its atoms. He claims that scientists are eager to explore the properties of this new form of carbon. What is wrong with the tabloid's claim? a. Nothing. The claim is believable. b. The claim must be false because an atom with eight protons would be oxygen, which is already known. c. The claim must be false because all forms of carbon are already known.2SC 3SC Copper is composed of two naturally occurring isotopes: Cu-63 with a mass of 62.94amuandCu-65 with a mass of 64.93amu. Look up the atomic mass of copper and determine which of the two isotopes is more abundant. a.Cu-63ismoreabundant.b.Cu-65ismoreabundant.c.Bothisotopesareequallyabundant.5SC Which pair of elements do you expect to be most similar? a. Mg and Ca b. N and Cl c. Al and C d. S and Si Which statement is true of the quantum mechanical model, but not of the Bohr model? a. Electrons orbit the nucleus in simple circular orbits, just like planets orbit the Sun. b. The exact path that an electron follows within an atom cannot be specified. c. The electron is attracted to the nucleus of the atom.Why is it important to understand atoms?2E What defines an element? How many naturally occurring elements exist?4E 5E 6E 7E 8E 9E 10E Explain the quantum mechanical model for the atom. How is it different from the Bohr model?Give two examples of each: a. alkali metal b. alkaline earth metal c. halogen d. noble gas e. metal f. nonmetal g. transition metal h. metalloid Which elements exist as diatomic molecules?Explain the difference and similarity between atomic mass and molar mass.15E Determine the charge of each of the following: a silver atom that has lost one electron a bromine atom that has gained one electron a chromium atom that has lost three electrons Determine the number of protons and electrons in each of the following ions: a.K+b.F-c.N3-d.Al3+Determine the number of protons and electrons in each of the following ions: a.Mg2+b.Se2-c.O2-d.Fe3+Give the atomic number (Z) and the mass number (A) for each of the following: a. a carbon atom with 8 neutrons b. an aluminum atom with 14 neutrons c. an argon atom with 20 neutrons d. a copper atom with 36 neutrons 20E The following isotopes have applications in medicine. Write their symbols in the form XZA. a. cobalt-60 b. phosphorus-32 c. iodine-131 d. sulfur-35 The following isotopes are important in nuclear power. Write their symbols in the form XZA. a. U-235 b. U-238 c. Pu-239 d. Xe-144 14C is used in carbon dating of artifacts. Determine the number of protons and neutrons in 14C.40K is used to measure the age of Earth. Determine the number of protons and neutrons in 40K.25E 26E Give electron configurations according to the Bohr model for each of the following elements. Try to not use Figure 3.11, but instead determine the configuration based on your knowledge of the number of electrons in each atom and the maximum number of electrons in each Bohr orbit. Indicate which of these elements you expect to be the most reactive and the least reactive. a. B b. Si c. Ca d. F e. Ar Give electron configurations according to the Bohr model for each of the following elements. Indicate which of these elements you expect to be the most reactive and the least reactive. a. He b. Al c. Be d. Ne e. O 29E How many valence electrons are in each element of problem 28?31E Draw electron configurations for each of the following elements according to the Bohr model. Indicate which electrons are valence electrons. a. Mg b. S c. He d. K Which two of the following elements would you expect to be most similar to each other? Why? Mg, N, F, S, Ne, Ca Group the following elements into three similar groups of two each: Na, O, Ne, Li, Ar, S We have seen that the reactivity of an element is determined by its electron configuration. What is the electron configuration of the ion Cl-? (Hint: You must add one additional electron beyond the number of electrons that chlorine would normally have.) How does its reactivity compare with neutral Cl? How would the reactivities of Na and Na+ compare?What is the electron configuration of Mg2+? How does its reactivity compare with neutral Mg? How do the reactivities of F- and F compare?Classify each of the following elements as a metal, a nonmetal, or a metalloid: a. Cr b. N c. Ca d. Ge e. Si Classify each of the following as a metal, a nonmetal, or a metalloid: a. Mn b. I c. Te d. Sb e. O Calculate the atomic mass of neon (Ne), which is composed of three naturally occurring isotopes with the following natural abundances and masses: a.90.51%Ne-20(mass=19.992amu)b.0.27%Ne-21(mass=20.993amu)c.9.22%Ne-22(mass=21.991amu)An element has two naturally occurring isotopes. Isotope 1 has a mass of 106.905amu and a relative abundance of 51.8%, and isotope 2 has a mass of 108.904amu and a relative abundance of 48.2. Find the atomic mass of this element and, referring to the periodic table, identify it.A fictitious element has two naturally occurring isotopes and has an atomic mass of 29.5amu. a. If the natural abundance of isotope 1 is 33.7%, what is the natural abundance of isotope 2? b. If the mass of isotope 2is30.0amu, what is the mass of isotope 1?Copper has two naturally occurring isotopes. Cu-63 has a mass of 62.939amu and a relative abundance of 69.17%. Use the atomic mass of copper to determine the mass of the second copper isotope.How many moles of titanium are present in 124 g of titanium?44E How many moles are there in each sample? a. 45 mg Ag b. 28 kg Zn c. 8.71027 He atoms d. 1 He atom How many moles are there in each sample? a. 55.0 g Ti b. 16.9 mg Na c. 7.951024 Ne atoms d. 25 Xe atoms What is the mass of each sample? a.1.8 mol S b.0.0067 mol Au c.0.552 mol Cu d.1 Na atom What is the mass of each sample? a.2.75 mol Fe b.0.115 mol Al c.125 mol Si d.1 Ni atom Determine the number of atoms in each sample. a.10.0 g Sr b.10.0 g Mg c.28.5 kg Zn Determine the number of atoms in each sample. a.45.0 g Si b.45.0 g Sn c.28.2 mg Pb How many Ag atoms are present in a piece of pure silver jewelry weighing 21.3 g?How many platinum atoms are in a pure platinum ring weighing 4.32 g?A pure gold necklace has a volume of 1.8cm3. How many gold atoms are in the necklace? The density of gold is 19.3g/cm3.A titanium bicycle component has a volume of 32cm3. How many titanium atoms are in the bicycle component? Titanium density = 4.50g/cm3.An iron sphere has a radius of 3.4 cm. How many iron atoms are in the sphere? Iron has a density of 7.86g/cm3, and a sphere has a volume of V=(43)r3.Calculate the number of atoms in the universe. The following steps will guide you through this calculation: a. Planets constitute less than 1% of the total mass of the universe and can, therefore, be neglected. Stars make up most of the visible mass of the universe, so we need to determine how many atoms are in a star. Stars are primarily composed of hydrogen atoms and our Sun is an average-sized star. Calculate the number of hydrogen atoms in our Sun given that the radius of the Sun is 7108 m and its density is 1.4g/cm3. The volume of a sphere is given by V=(43)r3 (Hint: Use the volume and the density to get the mass of the Sun.) b. The average galaxy (like our own Milky Way galaxy) contains 11011 stars, and the universe contains 1109 galaxies. Calculate the number of atoms in an average galaxy and finally the number of atoms in the entire universe. c. You can hold 11023 atoms in your hand (five copper pennies constitute 1.41023 copper atoms.) How does this number compare with the number of atoms in the universe?The introduction to this chapter states that everything is made of atoms, including ourselves. Does that affect the way you view human life? Do the atoms in our bodies follow the same physical laws as atoms in soil or rocks or water? If so, does this make human life any less unique?Suppose the absolute value of the charge of the electron was slightly greater than the charge of a proton. How would matter behave? What does this tell you about how small changes in the atomic realm affect the macroscopic realm?When we refer to doughnuts or cookies, we often refer to 1doz of them, which corresponds to 12. Why is the dozen an inconvenient number when referring to atoms? Why is Avogadros number, 6.0221023, more convenient?60E Why does Avogadros number have such an odd value? Why not pick a nice round number like 1.01024?62E 63E 64E Here are three fictitious elements and a molecular view of the atoms that compose them. The molar mass of the middle element, (b), is 25 grams per dozen (g/doz). (The atoms of these fictitious elements are much larger than ordinary atoms.) Based on the size of the atoms, do you expect the atomic masses of elements (a) and (c) to be greater than or less than (b)? How many atoms are present in 175 g of element (b)?66E Gather any two of the following items, measure their dimensions, and calculate the number of atoms present in the item. a. a copper penny (pre-1983), density of copper = 8.96g/cm3 b. a nickel (assume that the nickel is pure nickel, Ni), density of nickel = 8.90g/cm3 c. a graphite pencil lead (pure carbon), density of carbon = 2.62g/cm3 d. a helium balloon (assume that the balloon is approximately spherical; the volume of a sphere is V=(43)r3, where r is the radius), density of helium gas = 0.0899 g/L Interpreting Chemical Formulas Determine the number of each type of atom in the following chemical formulas: CCl4 Al2(SO4)3 4.2YT 4.3YT 4.4YT Calculating Formula Mass Calculate the formula mass of dinitrogen monoxide (N2O), an anaesthetic gas also called laughing gas.Using the Molar Mass to Find the Number of Molecules in a Sample of a Compound Calculate the number of carbon tetrachloride (CCl4) molecules in 3.82 g of carbon tetrachloride.4.7YT Chemical Formulas as Conversion Factors (Mass to Mass) How many grams of Oarein2.5gramsofCO2?4.9YT 4.10YT Using Chemical Equation Coefficients as Conversion Factors (Mass to Mass) One of the reactions occurring in automobile engines is the combustion of octane (C8H18): 2C8H18+25O216CO2+18H2O Assume that gasoline is pure octane and that you burn approximately 6.44104 grams of octane per week (about 20 gal). How many grams of CO2 are produced?1SC 2SC 3SC 4SC The coefficients in the chemical reaction 2A+3B products give us a relationship between which of the following: a. grams of A and grams of B b. density of A and density of B c. moles of A and moles of B 6SC In Chapter 3, we learned that all matter is composed of atoms. In this chapter, we learned that most common substances are either compounds or mixtures of compounds. How can these both be true? Explain.Name some common everyday compounds.3E 4E 5E 6E 7E What is the difference between a common name for a compound and a systematic name?9E 10E 11E 12E 13E 14E Why must chemical equations be balanced?Explain the numerical relationships inherent in a chemical equation.Chemical Formulas Determine the number of each type of atom in each chemical formula: a.CaF2b.CH2Cl2c.MgSO4d.Sr(NO3)2 Determine the number of each type of atom in each chemical formula: a.Na2Ob.CF2Cl2c.K2CO3d.Mg(HCO3)2 Classify each compound as ionic or molecular: a.KClb.CO2c.N2Od.NaNO3 Classify each compound as ionic or molecular: a.COb.ZnBr2c.CH4d.NaF 21E 22E 23E 24E 25E 26E Give a chemical formula for each compound: a. nitrogen dioxide b. calcium chloride c. carbon monoxide d. calcium sulfate e. sodium bicarbonate Give a chemical formula for each compound: a. sulfur trioxide b. phosphorus pentachloride c. carbon disulfide d. silicon tetrachloride e. potassium hydroxide 29E Calculate the formula mass for each compound: a.NaCl(tablesalt)b.CH4(naturalgas)c.NH4Cld.C12H22O11(sugar)The formula mass of an unknown compound containing only C and H is 44 amu. What is its molecular formula?The formula mass of an unknown compound containing only C and H is 70.1 amu. What is its molecular formula?Mole Conversions How many moles of CO2 are contained in a 10.5-g sample of dry ice (pure solid CO2)?What is the mass of 2.55 moles of water?The active ingredient in aspirin is acetylsalicylic acid, which has the chemical formula C9H8O4. An aspirin pill contains 300.0 mg of acetylsalicylic acid. How many moles of acetylsalicylic acid does it contain?The active ingredient in Tylenol is acetaminophen (C8H9NO2). A single regular-strength Tylenol tablet contains 2.15103 mol of acetaminophen. What is the mass (in mg) of the acetaminophen in the tablet?Calculate the number of water molecules (H2O) in 35.7 g of water.Acetone (C3H6O) is used as nail polish remover. If the amount of acetone used to remove the polish from one fingernail is 0.32g, how many molecules were used?Determine the number of sugar molecules in 7.5 g of sugar (C12H22O11).One drop of water from a medicine dropper has a volume of approximately 0.050mL(1mL=1cm3). a. Determine the number of water molecules in a drop of water. (The density of water is 1.0g/cm3). b. How many H atoms would be present in these molecules?How many chlorine atoms are in each of the following? a.124CCl4moleculesb.38HClmoleculesc.89CF2Cl2moleculesd.1368CHCl3molecules How many hydrogen atoms are in each of the following? a.5H2Omoleculesb.58CH4moleculesc.1.41022C12H22O11moleculesd.14dozenNH3molecules 43E Find the number of moles of nitrogen in each of the following: a.1.22molN2H4b.0.67molN2Oc.0.67molNOd.37.1gN2 The U.S. Food and Drug Administration recommends that you consume less than 2.4 g of sodium per day. How much sodium chloride can you consume and still be within the FDA limit?The scientific consensus indicates that adults should consume about 2.0 mg of fluoride per day for healthy teeth. How much sodium fluoride needs to be consumed to get 2.0 mg of fluoride?Determine the mass of iron (in kilograms) contained in 34.1 kilograms of Fe2O3.Determine the mass of carbon (in kilograms) contained in 143 kilograms of CO2.Balancing Chemical Equations Balance each chemical equation: a.HCl+O2H2O+Cl2b.NO2+H2OHNO3+NOc.CH4+O2CO2+H2O 50E 51E 52E Water can be synthesized according to the following unbalanced chemical equation: H2+O2H2O a. Balance the equation. b. How many moles of H2O can be produced if you have 2.72 mol of O2 and an unlimited amount of H2? c. How many moles of H2 would be necessary to produce 10.0 g of water? d. How many grams of water would be formed by the complete reaction of 2.5 g of H2?Billions of pounds of urea, CO(NH2)2, are produced annually for use as a fertilizer. The principal reaction employed is: 2NH3+CO2CO(NH2)2+H2O By assuming unlimited amounts of CO2, how many moles of urea can be produced from each of the following amounts of NH3? a.2molNH3b.0.45molNH3c.10gNH3d.2.0kgNH3 55E 56E 57E 58E 61E For each space-filling molecular model, write a chemical formula. Carbon atoms are black, hydrogen atoms are white, oxygen atoms are red, and nitrogen atoms are blue.For each chemical reaction, draw in the missing molecules necessary to balance their equations. Carbon atoms are black, hydrogen atoms are white, oxygen atoms are red, and nitrogen atoms are blue.Drawing Lewis Structures for Ionic Compounds Draw a Lewis structure for SrCl2.Using Lewis Structures to Determine the Correct Chemical Formula for Ionic Compounds Use Lewis structures to determine the correct chemical formula for the compound formed between LiandO.5.3YT 5.4YT Drawing Lewis Structures for Covalent Compounds III Draw a Lewis structure for HC2H. (The two carbon atoms are in the middle, with one hydrogen atom attached to each.)5.6YT 5.7YT 5.8YT 5.9YT Determining if a Molecule Is Polar Is SCl2 a polar or nonpolar molecule?Based on the Lewis structures for hydrogen and helium, explain why buoyant balloons are filled with helium instead of hydrogen gas, even though hydrogen gas is cheaper and more buoyant. HHe:: a. Helium's duet makes it stable and inert (unreactive). b. Helium's duet makes it unstable and chemically reactive. c. Helium has one more electron than hydrogen, which helps add color to the balloon.2SC 3SC 4SC Which one of the following bonds is polar? a. a bond between two identical atoms b. a bond between two atoms with the same electronegativity c. a bond between two atoms with different electronegativities 6SC Why is salt, NaCl, relatively harmless even though the elements that compose it, sodium and chlorine, are toxic?If sodium is dropped into water, a loud fizzing noise is heard, and sparks fly from the sodium. What do you suppose is occurring?Explain ionic bonding according to Lewis theory.4E

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