4-44 Answer true or false.
(a) The mole is a counting unit, just as a dozen is acounting unit.
(b)
(c) Avogadro’s number, to three significant figures, is formula units per mole.
(d) 1 mol of H2O contains formula units.
(e) 1 mol of H2O has the same number of molecules as 1 mol of H2O2.
(f) The molar mass of a compound is its formula weight expressed in amu.
(g) The molar mass of H2O is 18 g/mol.
(h) 1 mol of H2O has the same molar mass as 1 mol of H2O2.
(i) 1 mol of ibuprofen, C13H18O2, contains 33 mol of atoms.
(j) To convert moles to grams, multiply by Avogadro’s number.
(k) To convert grams to moles, divide by molar mass.
(l) 1 mol of H2O contains 1 mol of hydrogen atoms and one mol of oxygen atoms.
(m) 1 mol of H2O contains 2 g of hydrogen atoms and 1 g of oxygen atoms.
(n) 1 mole of H2O contains 18.06 X 10 atoms.
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Chapter 4 Solutions
Introduction to General, Organic and Biochemistry
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- 4-103 Caffeine, a central nervous system stimulant, has the molecular formula C8H10N402. (a) How many moles of caffeine are present in 6.19 1025 molecules of caffeine? (b) Imagine you dissolve caffeine in water to a volume of 100.0 mL, which is known to have a density of 1.23 g/mL. How many molecules of caffeine are present in this volume? (c) How many nitrogen atoms are present in 3.5 mg of caffeine? (d) Complete the skeletal structure of caffeine, where all the bonded atoms are shown but double bonds, triple bonds, and/or lone pairs are missing. (e) Identify the various types of geometries present in each central atom of caffeine using VSEPR theory. (f) Determine the various relative bond angles associated with each central atom of caffeine using VSEPR theory (g) What is the most polar bond in caffeine? (h) Would you predict caffeine to be polar or nonpolar? (j) Consider the combustion of caffeine, which results in formation of NO2(g) as well as other expected products. Write a balanced chemical equation for this reaction. (j) The heat of combustion for caffeine is 2211 kcall/mol. How much heat will be given off if 0.81 g of caffeine is burned completely? (k) Calculate the weight of H2O(g) that can be prepared from 8.00 g of caffeine mixed with 20.3 g of oxygen gas.arrow_forward3.122 What type of reasoning were we using when we developed the equation for dilution, MiVi=MfVf ?arrow_forward3.105 Nitric acid is often sold and transported as a concentrated 16 M aqueous solution. How many gallons of such a solution would be needed to contain the roughly 2.1109 pounds of HNO3 produced annually in the United States?arrow_forward
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