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mastering chemistry.com/myct/itemview?assignmentProblemID-77781064 ecure https em 210 Section 2 Spring 2017 agt homework t Avogadro's Number Avogadro's Number previous 8 of Part A ng Goal Aflask contains 0,420 mol of liquid bromine, Bra. Determine the number of bromine molecules present in the flask. Express your answer numerically in molecules To use Avogadros number to convert between microscopic units of atoms and molecules to the macroscopic world of chemical experiments. A mole is a unit of matter that represents a known IVO AE number of particies that is arge enough to be weghed Co 6.022 x 10 a formula units, as shown in the following Submit Hints My Answers Give up Review Part The term formula unt is a generic phrase that can mean molecule, alom, ion, or whatever by the You may know that a million is 10 ,abilion is 10 and atrilion is 1012.A tilwon trilion would be 10 which is also known as a septilon. chemical formula. For example, a mole of He contains 6022 x 10 a helium atoms A mole of N2 contains 6.022 x 10 a diatomic N2 but double that molecules number of nitrogen atoms. Part B Calculate the mass of 1.00 x 1024 (a septilion) molecules of watergven that the molar mass of water is 18.02 g/mol. Express the answer numerically in grams. Submit Hint Mr.Answers Guve up Review Pan Correct This value is dose to the mass of a fluid ounce of water (296 mL). Now you know that one suid ounce of water contains approximately 10" (a trillion trillion) molecules Part C The fuel used in butane is 58.12 g

Explanation / Answer

A)

We know that one mole of any substance contains Avogadros number of molecules that is 6.022 x 1023

So

1 mole of Br2 = 6.022 x 1023 molecules

therefore

0.420 moles of  Br2 = 0.420 moles of Br2 x 6.022 x 1023 molecules / 1 mol of Br2

= 2.53 x 1023 molecules

B)

Now we know that for any substance 1 mole = 6.022 x 1023 molecules

therefore

1 molecule = 1 mol / 6.022 x 1023

then

1.00 x 1024 molecules = 1.00 x 1024 x 1 mol / 6.022 x 1023

= 1.66 moles

Now

Mole = mass / molar mass

therefore

mass = mole x molar mass

= 1.66 moles x 18.02 g/mol

= 29.92 g

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