1 Chemistry: An Introduction 2 Measurements And Calculations 3 Matter 4 Chemical Foundations: Elements, Atoms, And Ions 5 Nomenclature 6 Chemical Reactions: An Introduction 7 Reactions In Aqueous Solutions 8 Chemical Composition 9 Chemical Quantities 10 Energy 11 Modern Atomic Theory 12 Chemical Bonding 13 Gases 14 Liquids And Solids 15 Solutions 16 Acids And Bases 17 Equilibrium 18 Oxidation–reduction Reactions And Electrochemistry 19 Radioactivity And Nuclear Energy 20 Organic Chemistry 21 Biochemistry Chapter8: Chemical Composition
8.1 Counting By Weighing 8.2 Atomic Masses: Counting Atoms By Weighing 8.3 The Mole 8.4 Learning To Solve Problems 8.5 Molar Mass 8.6 Percent Composition Of Compounds 8.7 Formulas Of Compounds 8.8 Calculation Of Empirical Formulas 8.9 Calculation Of Molecular Formulas Chapter Questions Section: Chapter Questions
Problem 1ALQ: n chemistry, what is meant by the term mole? What is the importance of the mole concept? Problem 2ALQ: hat is the difference between the empirical and molecular for mulas of a compound? Can they ever be... Problem 3ALQ: substance A2B is 60% A by mass. Calculate the present B (by mass) for AB2 . Problem 4ALQ: ive the formula for calcium phosphate and then answer the following questions: l type='a'> Calculate... Problem 5ALQ: ow would you find the number of “chalk molecules” it takes to write your name on the hoard? Explain... Problem 6ALQ: 0.821 -mol sample of a substance composed of diatom of molecules has a mass of 131.3 g. Identify... Problem 7ALQ: ow many molecules of water are there in a 10.0-g sample of water? How many hydrogen atoms are there... Problem 8ALQ: hat is the mass (in grams) of one molecule of ammonia? Problem 9ALQ: onsider separate 100.0-g samples of each of the following: NH3 , N2O , N2H4 , HCN , HNO3 . Arrange... Problem 10ALQ: A molecule has a mass of 4.651023 g. Provide two possible chemical formulas for such a molecule. Problem 11ALQ: Differentiate between the terms atomic mass and molar mass. Problem 12ALQ: Consider Figure 4.19 in the text. Why is it that the formulas for ionic compounds are always... Problem 13ALQ: Why do we need to count atoms by weighing them? Problem 14ALQ: The following claim is made in your text: 1 mole of marbles is enough to cover the entire earth to a... Problem 15ALQ: Estimate the length of time it would take you to count to Ayogadro’s number. Provide mathematical... Problem 16ALQ: Suppose Avogadro’s number was 1000 instead of 6.0221023 . How, if at all, would this affect the... Problem 17ALQ: Estimate the number of atoms in your body and provide mathematical support. Because it is an... Problem 18ALQ: Consider separate equal mass samples of magnesium, zinc, and silver. Rank them from greatest to... Problem 19ALQ: You have a 20.0-g sample of silver metal. You are given 10.0 g of another metal and told that this... Problem 20ALQ: How would you find the number of “ink molecules” it takes to write your name on a piece of paper... Problem 21ALQ: True or false? The atom with the largest subscript in a formula is the atom with the largest percent... Problem 22ALQ: Which of the following compounds have the same empirical formulas? mg... Problem 23ALQ: The percent by mass of nitrogen is 46.7% for a species containing only nitrogen and oxygen. Which of... Problem 24ALQ Problem 25ALQ: Give the empirical formula for each of the compounds represented below. mg... Problem 1QAP: erchants usually sell small nuts, washers, and bolts by weight (like jelly beans!) rather than by... Problem 2QAP: he “Chemistry in Focus” segment Plastic That Talks and Listens! discusses polyvinylidene difluoride... Problem 3QAP: efine the amu. What is one amu equivalent to in grains? Problem 4QAP: hat do we mean by the average atomic mass of an element? What is “averaged” to arrive at this... Problem 5QAP: sing the average atomic masses for each of the following elements (see the table inside the cover of... Problem 6QAP: sing the average atomic masses for each of the following elements (see the table inside the front... Problem 7QAP Problem 8QAP: he atomic mass of copper is 63.55 amu. What would be the mass of 75 copper atoms? How many copper... Problem 9QAP: here are _________ iron atoms present in 55.85 g of iron. Problem 10QAP: There are 6.0221023 zinc atoms present in g of zinc. Problem 11QAP: Suppose you have a sample of sodium weighing 11.50 g. How many atoms of sodium are present in the... Problem 12QAP: Consider a sample of silver weighing 30OE0 g. How many at oms of silver are present in the sample?... Problem 13QAP: What mass of hydrogen contains the same number of atoms as 7.00 g of nitrogen? Problem 14QAP: What mass of cobalt contains the same number of atoms as 57.0 g of fluorine? Problem 15QAP: If an average sodium atom has a mass of 3.821023 g. what is the mass of a magnesium atom in grams? Problem 16QAP: Ifan average fluorine atom has a mass of 3.161023 g, what is the average mass of a chlorine atom in... Problem 17QAP: Which has the smaller mass, 1 mole of He atoms or 4 moles of H atoms? Problem 18QAP: Which weighs less, 0.25 mole of xenon atoms or 2.0 moles of carbon atoms? Problem 19QAP: Use the average atomic masses given inside the front cover of this book to calculate the number of... Problem 20QAP: Use the average atomic masses given inside the front cover of this hook to calculate the number of... Problem 21QAP: Use the average atomic masses given inside the front cover of this book to calculate the mass in... Problem 22QAP: Use the average atomic masses given inside the front cover ofthis book to calculate the mass in... Problem 23QAP: Using the average atomic masses given inside the front cover of this book, calculate the number of... Problem 24QAP: Using the average atomic masses given inside the front cover of this book, calculate the indicated... Problem 25QAP: The _________ of a substance is the mass (in grams) of 1 mole of the substance. Problem 26QAP Problem 27QAP: Give the name and calculate the molar mass for each of the following substances. l type="a"> H3PO4... Problem 28QAP: Give the name and calculate the molar mass for each of the following substances. l type="a"> KHCO3... Problem 29QAP: Write the formula and calculate the molar mass for each of the following substances. l type='a'>... Problem 30QAP: Write the formula and calculate the molar mass for each of the following substances. l type='a'>... Problem 31QAP: Calculate the number of moles of the indicated substance present in each of the following samples. l... Problem 32QAP Problem 33QAP Problem 34QAP: Calculate the number of moles of the indicated substance present in each of the following samples. l... Problem 35QAP: Calculate the mass in grams of each of the following samples. l type='a'> 1.25 moles of aluminum... Problem 36QAP: Calculate the mass in grams of each of the following samples. l type="a"> 6.14104 moles of sulfur... Problem 37QAP: Calculate the mass in grams of each of the following samples. l type="a"> 0.251 mole of ethyl... Problem 38QAP: Calculate the mass in grams of each of the following samples. l type="a"> 0.994 mole of benzene,... Problem 39QAP: Calculate the number of molecules present in each of the following samples. l type="a"> 4.75 mmol of... Problem 40QAP: Calculate the number of molecules present in each of the following samples. oles of sulfur dioxide,... Problem 41QAP: Calculate the number of moles of carbon atoms present in eachof the following samples. l type="a">... Problem 42QAP: Calculate the number of moles of sulfur atoms present in each of the following samples. l type='a'>... Problem 43QAP: The mass fraction of an element present in a compound can be obtained by comparing the mass of the... Problem 44QAP: If the amount of a sample doubles, what happens to the percent composition of each element in the... Problem 45QAP: lculate the percent by mass of each element in the following compounds. l type='a'> HClO3 i>UFl4... Problem 46QAP: Calculate the percent by mass of each element in the following compounds. l type="a"> ZnO i>Na2S... Problem 47QAP: Calculate the percent by mass of the element listed first in the formulas for each of the following... Problem 48QAP: Calculate the percent by mass of the element listed first in the formulas for each of the following... Problem 49QAP Problem 50QAP: What is the mass percent of oxygen in each of the following compounds? l type='a'> carbon dioxide... Problem 51QAP: For each of the following samples of ionic substances, calculate the number of moles and mass of the... Problem 52QAP: For each of the following ionic substances, calculate the percentage of the overall molar mass of... Problem 53QAP Problem 54QAP: Explain lo a friend who has not yet taken a chemistry course what is meant by the empirical formula... Problem 55QAP: Give the empirical formula that corresponds to each of the following molecular formulas. l type="a">... Problem 56QAP: Which of the following pairs of compounds have the same empirical formula? etylene, C2H2 , and... Problem 57QAP: A compound was analyzed and was found to contain the following percentages of the elements by mass:... Problem 58QAP: A compound was analyzed and was found to contain the following percentages of the elements by mass:... Problem 59QAP: A 0.59980-g sample of a new compound has been analyzed and found to contain the following masses of... Problem 60QAP: A compound was analyzed and was found to contain the following percentages of the elements by mass:... Problem 61QAP: If a 1.271-g sample of aluminum metal is heated in a chlorine gas atmosphere, the mass of aluminum... Problem 62QAP: A compound was analyzed and was found to contain the following percentages of the elements by mass:... Problem 63QAP: When 3.269 g of zinc is heated in pure oxygen, the sample gains 0.800 g of oxygen in forming the... Problem 64QAP: If cobalt metal is mixed with excess sulfur and heated strongly, a sulfide is produced that contains... Problem 65QAP: If 1.25 g of aluminum metal is heated in an atmosphere of fluorine gas. 3.89 g of aluminum fluoride... Problem 66QAP: If 2.50 g of aluminum metal is heated in a stream of fluorine gas, it is found that 5.28 g of... Problem 67QAP: A compound used ¡n the nuclear industry has the following composition: uranium. 67.61%; fluorine,... Problem 68QAP: A compound was analyzed and was found to contain the following percentages of the elements by mass:... Problem 69QAP: A compound has the following percentage composition by mass: copper, 33.88%; nitrogen, 14.94%;... Problem 70QAP: When lithium metal is heated strongly in an atmosphere of pure nitrogen, the product contains 59.78%... Problem 71QAP: A compound has been analyzed and has been found to have the following Composition: copper, 66.75%;... Problem 72QAP: Tetraphenylporphyrin is a synthetic compound that resembles naturally occurring porphyrins.... Problem 73QAP: When 1.00 mg of lithium metal is reacted with fluorine gas (F2) , the resulting fluoride salt has a... Problem 74QAP: Phosphorus and chlorine form two binary compounds, in which the percentages of phosphorus are 22.55%... Problem 75QAP: How does the molecular formula of a compound differ from the empirical formula? Can a compound’s... Problem 76QAP Problem 77QAP: A binary compound of boron and hydrogen has the following percentage composition: 78.14% boron.... Problem 78QAP: A compound with empirical formula CH was found by experiment to have a molar mass of approximately... Problem 79QAP: A compound with the empirical formula CH2 was found to have a molar mass of approximately 84 g. What... Problem 80QAP: A compound with empirical formula C2H5O was found in a separate experiment to have a molar mass of... Problem 81QAP: A compound having an approximate molar mass of 165170 g has the following percentage composition by... Problem 82QAP: A compound containing only sulfur and nitrogen is 69.6% S by mass. The molar mass is 184 g/mol. What... Problem 83AP: Use the periodic table shown in Fig. 4.9 to determine the atomic mass (per mole) or molar mass of... Problem 84AP: Complete the following table. l> Mass of Sample Moles of Sample Atoms in Sample 5.00 g AI td>... Problem 85AP: Complete the following table. l> Mass of Sample Moles of Sample Molecules in Sample Atoms in Sample... Problem 86AP: Consider a hypothetical compound composed of elements X, Y, and Z with the empirical formula X2YZ3 .... Problem 87AP: A binary compound of magnesium and nitrogen is analyzed, and 1.2791 g of the compound ¡s found to... Problem 88AP: When a 2.11 8-g sample of copper is heated in an atmosphere in which the amount of oxygen present is... Problem 89AP: Hydrogen gas reacts with each of the halogen elements to form the hydrogen halides (HF,HCl,HBr,HI) .... Problem 90AP: Calculate the number of atoms of each element present in each of the following samples. l type='a'>... Problem 91AP: Calculate the mass in grams of each of the following samples. l type='a'> 10,000,000,000 nitrogen... Problem 92AP: Calculate the mass of carbon in grams, the percent carbon by mass, and the number of individual... Problem 93AP: Find the item in column 2 that best explains or completes the statement or question in column 1. l... Problem 94AP: You have a sample of copper (Cu) and a sample of aluminum (Al). You have an equal number of atoms in... Problem 95AP: Calculate the number of grams of cobalt that contain the same number of atoms as 2.24 g of iron. Problem 96AP: A compound was analyzed and found to contain the following percentages of elements by mass: carbon,... Problem 97AP: Calculate the number of grains of lithium that contain the same number of atom as 1 .00 kg of... Problem 98AP: Given that the molar mass of carbon tetrachloride, CCl4 , is 153 g, calculate the mass in grams of 1... Problem 99AP: Calculate the mass in grains of hydrogen present in 2.500 g of each of the following compounds. l... Problem 100AP: f you have equal mole samples of NO2 and F2 , which of the following must be true? l type='a'> The... Problem 101AP: strikingly beautiful copper compound with the common name “blue vitriol” has the following elemental... Problem 102AP: certain transition metal ion (Mn+) forms a compound with oxygen (MxOy) . The molar mass of the... Problem 103AP Problem 104AP Problem 105AP Problem 106AP: f an average sodium atom weighs 22.99 amu, how many sodium atoms are contained in 1.981013 amu of... Problem 107AP Problem 108AP Problem 109AP Problem 110AP Problem 111AP Problem 112AP Problem 113AP: alculate the number of moles of the indicated substance present in each of the following samples. l... Problem 114AP: f you have equal-mole samples of each of the following compounds, which compound contains the... Problem 115AP Problem 116AP Problem 117AP: alculate the number of moles of hydrogen atoms present in each of the following samples. l type='a'>... Problem 118AP: ow many anions are there in 5.00 g of calcium bromide? Problem 119AP Problem 120AP Problem 121AP: 1.2569-g sample of a new compound has been analyzed and found to contain the following masses of... Problem 122AP: hat mass of sodium hydroxide has the same number of oxygen atoms as 100.0 g of ammonium carbonate? Problem 123AP: hen 2.004 g of calcium is heated in pure nitrogen gas. The sample gains 0.4670 g of nitrogen.... Problem 124AP: opical hydrocortisone is often used to treat a variety of skin conditions, such as insect bites,... Problem 125AP: hen 1.00 g of metallic chromium is heated with elemental chlorine gas. 3.045 g of a chromium... Problem 126AP: hen barium metal is heated in chlorine gas, a binary compound forms that consists of 65.95% Ba and... Problem 127CP Problem 128CP: itamin B12 , cyancobalamin, is essential for human nutrition. Its molecular formula is... Problem 129CP Problem 130CP: . How many atoms of carbon are present in 1 .0 g of CH4O ? How many atoms of carbon are present in... Problem 131CP: onsider samples of phosphine (PH3) , water (H2O) . Hydrogen sulfide (H2S) , and hydrogen fluoride... Problem 132CP: he chemical formula for aspirin is C9H8O4 . What is the mass percent for each element in 1 mole of... Problem 133CP Problem 134CP: compound with molar mass 180.1 g/mol has the following composition by mass: 40.0% 6.70% 53.3%... Problem 4ALQ: ive the formula for calcium phosphate and then answer the following questions: l type='a'> Calculate...
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Concept explainers
Answer the following questions on Avogadro's Number and the mole. (SHOW WORK step by step and round ALL final answers to 2 decimal places)
How many molecules are in 0.25 moles of CH4 ?
How many total atoms are in 1.0 moles of H2 O?
Definition Definition Number of atoms/molecules present in one mole of any substance. Avogadro's number is a constant. Its value is 6.02214076 × 10 23 per mole.
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