1. How many MOLECULES of water are present in 3.55 moles of this compound? molecules. 2. How many MOLES of water are present in 8.62×1022 molecules of this compound? moles

erhaps the most important concept in introductory chemistry concerns what a mole of a substance represents. The mole concept will come up again and again in later chapters in this book. What does one mole of a substance represent on a microscopic, atomic basis? What does one mole of a substance represent on a macroscopic, mass basis? Why have chemists defined the mole in this manner?

hat is the difference between the empirical and molecular for mulas of a compound? Can they ever be the same? Explain.

Complete the following table. l> Mass of Sample Moles of Sample Molecules in Sample Atoms in Sample 4.24 g msp;C6H6 0.224 mol msp;H2O msp;2.711022 molecules msp;CO2 1.26 mol HCl td> msp;2.211024 molecules msp;H2O 0.297 g msp;CH3OH

1. Which of the following hydrocarbons has the highest mass percentage of carbon? methane, CH4 ethane, C2H6 propane, C3H8 butane, C4H10

Pain Relief Acetaminophen, a common aspirin substitute, has the formula C8H9NO2 . Determine the number of molecules of acetaminophen in a 500-mg tablet.

ow many molecules of water are there in a 10.0-g sample of water? How many hydrogen atoms are there in this sample?

Use the average atomic masses given inside the front cover ofthis book to calculate the mass in grams of each of the following samples. l type='a'> 0.00552 mole of calcium 6.25 mmol of boron (1mmol=11000mole) i>135 moles of aluminum 1.34107 moles of barium 2.79 moles of phosphorus 0.0000997 mole of arsenic

To find the mass of a mole of an element, one looks up the atomic mass of the element in a table of atomic masses see Appendix III or the Periodic Table. The molar mass of an element is simply the mass in grams of that element that is numerically equal to its atomic mass. For a compound substance, the molar mass is equal to the mass in grams that is numerically equal to the sum of the atomic masses in the formula of the substance. Find the molar mass of Cu_g/molCl_g/molH_g/mol O_g/molH2O_g/mol

Write a sentence that describes how to determine the number of moles of a compound in a known mass of the compound if we know its molecular formula.