# General Chemistry I: Problems and Solutions

Quiz 3, Fall 2009 – Drs. Foy and Steel

Name

SOLUTIONS

1. ( 2 points) Calculate the number of moles in 0.41 g titanium. .

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2. ( 2 points) What is the mass of 5.1 mol P?

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3. ( 2 points) A 3.6 g sample of lithium contains how many atoms? .

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4. (4 points) The density of iron is 7.87 g/cm3. Calculate the number of iron atoms present in a cube that has an edge of 3.00 cm.

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5. (4 points) You have 0.330 mole of each of the following elements: Be, B, Br, Ba, and Bi. Which sample has the largest mass and why?

Since all of these samples have the same number of atoms (based on the moles) the sample with the heaviest atoms will have the largest mass. Thus, the bismuth (Bi) sample will have the largest mass because its atoms have the greatest atomic mass, about 209 g/mol.

6. (4 points) Calculate the molar mass of Magnesium in grams/mol given the following data (Show your complete calculation):

Isotope

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natural

abundance

isotope mass

(grams/mol)

24

78.99%

23.9858

25

10.00%

24.9858

26

11.01%

25.9826

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Mg

Mg

Mg

7. (4 points) If an average grain of rice has a volume equal to 6.0mm3, what is the volume of 2.5 moles of rice reported in cubic inches?

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8. (3 points) What mass of He contains the same number of atoms as 5.00 g Kr? .

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9. (15 points) Complete the table of names and formulas.

Formula

Name

Fe2(Cr2O7)3

iron (III) dichromate

NaCH3COO

Sodium acetate

SiCl4

silicon tetrachloride

Pb(OH)4

lead (IV) hydroxide

KClO3

potassium chlorate

GaPO4

gallium phosphate

KClO4

potassium perchlorate

CH3COOH

acetic acid

N2O5

dinitrogen pentaoxide

Al(CN)3

aluminum cyanide

Ca(NO3)2

calcium nitrate

SF6

sulfur hexafluoride

CrO

chrominum (II) oxide

RbCl

rubidium chloride

P4 S9...

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