A EXAM 3a

CHEM 103A

Name: ____________________

Fall 2012

EXAM 3a

Lab Section___________________

Please read all instructions before answer a problem. Please show all work for full credit (you will not be marked down for no work shown, but it will cost you if you get the problem incorrect!). Please answer only as many questions as requested by a section. If you answer more than is requested, I will grade the lowest scores in the section! Section 1: Conceptual. Please answer 7 out of 9 of the following problems (10 points each) 1. TRUE/FALSE – If a statement is FALSE, correct the statement so that it is TRUE: Example: TRUE/FALSE – An atom MOLECULE is a particle consisting of multiple elements bonded together in a specific geometric arrangement.

1. TRUE/FALSE – A covalent bond is between a metal and a non-metal 2. TRUE/FALSE – A cation has a positive charge, an anion has a negative charge. 3. TRUE/FALSE – An empirical formula shows the actual amounts of each element in a compound. 4. TRUE/FALSE – Atomic elements exist as covalently-bonded molecules (Ex. H2, N2) 5. TRUE/FALSE – An ionic compound name must have a total charge of 0. 2. TRUE/FALSE – If a statement is FALSE, correct the statement so that it is TRUE: Example: TRUE/FALSE – An atom MOLECULE is a particle consisting of multiple elements bonded together in a specific geometric arrangement.

1. TRUE/FALSE – The correct name for CaCl2 is Calcium (II) chloride 2. TRUE/FALSE – The correct formula for Iron (III) phosphate is FePO4 3. TRUE/FALSE –The polyatomic anion known as hypochlorite has the formula ClO24. TRUE/FALSE – Zn2+, Ag+, and Co2+ always have the same charge, so it is not necessary to have the roman numeral in their names. 5. TRUE/FALSE – The correct name for Co3(PO4)2∙8H2O is Cobalt(II) phosphate nonahydrate.

1

CHEM 103A

Fall 2012

EXAM 3a

3. Naming – Fill in the following Table: (if molecular, leave cation and anion blank). Only find the formula mass for those without a shaded cell! Name Formula Covalent or Cation (w/ Anion (w/ Formula Ionic charge) charge) Mass (g/mol) 2+ Barium Ba(OH)2 Ionic Ba OH 171.342 hydroxide CuNO2 Ionic

Ag+

HSO4-

Li2O2 Dichromic acid SO2

4. Naming – Fill in the following Table: (if molecular, leave cation and anion blank). Only find the formula mass for those without a shaded cell! Name Formula Covalent or Cation (w/ Anion (w/ Formula Ionic charge) charge) Mass (g/mol) 2+ Barium Ba(OH)2 Ionic Ba OH 171.342 hydroxide Tetranitrogen tetraselinide Ionic

Mo6+

HPO42-

HNO2(aq) Hydrobromic acid Acetic Acid

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CHEM 103A

Fall 2012

EXAM 3a

5. Naming – Fill in the following Table: (if molecular, leave cation and anion blank). Only find the formula mass for those without a shaded cell! Name Formula Covalent or Cation (w/ Anion (w/ Formula Ionic charge) charge) Mass (g/mol) 2+ Barium Ba(OH)2 Ionic Ba OH 171.342 hydroxide Dinitrogen trioxide FeF2∙4H2O Ionic

Cr6+

PO43-

Chlorous acid Cs3N

6. Balancing – Balance each of the following chemical equations: 1. ___ H2(g) + Br2(g) → ___HBR(g) 2. ____ CoBr3 + ____ CaSO4  ____ CaBr2 + ____ Co2(SO4)3 3. ____ LiNO3 + ____ CaBr2  ____ Ca(NO3)2 + ____ LiBr 4. ____ NaCN + ____ CuCO3  ____ Na2CO3 + ____ Cu(CN)2 5. ____ PbBr2 + ____ HCl  ____ HBr + ____ PbCl2

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CHEM 103A

Fall 2012

EXAM 3a

7. Balancing – Balance each of the following chemical equations: 1. ____ Mn + ____ HI  ____ H2 + ____ MnI3 2. ____ P4 + ____ Br2  ____ PBr3 3. ____ AgNO3 + ____ Li  ____ LiNO3 + ____ Ag 4. ___ RbNO3 + ____ BeF2  ____ Be(NO3)2 + ____ RbF 5. ___ Al + ____ HCl  ____ H2 + ____ AlCl3

8. Write a balanced chemical equation for the reaction of aqueous sodium carbonate with aqueous copper(II) chloride to form solid copper(II) carbonate and aqueous sodium chloride

9. Write a balanced chemical equation for the photosynthesis reaction in which gaseous carbon dioxide and liquid water react in the presence of chlorophyll to produce aqueous glucose (C6H12O6) and oxygen gas.

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CHEM 103A

Fall 2012

EXAM 3a

Section 2: Calculations. Please answer 7 out of 9 of the following problems (10 points each) 1. How many molecules of ethanol (C2H5OH) (the alcohol in alcoholic beverages) are present in 165 mL of ethanol? (the density of ethanol is 0.789 g/cm3)

2. Tartaric acid is a white, powdery substance that is the coating for sour candies. Combustion analysis of a 12.01 g sample of tartaric acid (containing only C, H, and O) produced 14.08 g CO2 and 4.32 g H2O. If the molecular mass of tartaric acid is 150.087 g/mol, what is the molecular formula?

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CHEM 103A

Fall 2012

EXAM 3a

3. Calculate the empirical formula for each of the following: a. Methyl butyrate: C 58.80%, H 9.87%, O 31.33% b. Vanillin: C 63.15%, H 5.30%, O 31.55%

4. A Freon leak in the air conditioning system of an older car releases 32 g of CF2Cl2 into the atmosphere per month. What mass of chlorine is emitted into the atmosphere each year by this car?

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CHEM 103A

Fall 2012

EXAM 3a

Equations

4 V  r 3 3

d

V  r 2h

V  l  w h



C

[



m V

F  32 K C  273.15 1.8

( ) ]

[

]

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