Keys for Tests Given Spring 2001

Key for Test 1

1. 1.7694 x 10⁴ Note that you don't round this. This is just a number and not involved in any calculations.

2. 1.7694 x 10^-5 Note that you don't round this. This is just a number and not involved in any calculations.

3. physical

4. chemical

5. 88.5 kgm

6. 114 meters

7. 9.22 ^oC

8. 0.645 dollars/liter

9. joule

10. 196 grams

11. 89.6 calories

12. 6 significant figures

13. 472 kcal

Key for Test 2 1. a.) oxygen, b.) potassium, c.) chlorine, d.) calcium

2.a.) P, b.) Ca, c.) C, d.) Zn

3. a.) 10 protons, 12 neutrons

b.) 17 protons, 18 neutrons

c.) 3 protons, 4 neutrons

d.) 86 protons, 124 neutrons

e.) 86 protons, 136 neutrons

4. a.) an ion is an atom with one or more electron(s) added (anion) or removed (cation).

b.) an isotope is an atom with the same number of electrons and protons as another atom, but with different numbers of neutrons.

5. a.) F^-, b.) Ar, c.) Br^-, d.) Na⁺

6. a.) 17 electrons, 17 protons, 20 neutrons

b.) 18 electrons, 19 protons, 20 neutrons

c.) 54 electrons, 53 protons, 74 neutrons

7. a.) Aluminum is more metallic, b.) Ga is more metallic

8.a.) 1s²2s

b.) 1s²2s²

c.) 1s²2s²2p²

d.) 1s²2s²2p⁶3s²3p³

e.) 1s²2s²2p⁶3s

9. a.) 1s²2s²2p⁶

b.) 1s²2s²2p⁶

c.) 1s²2s²2p⁶

d.) 1s²2s²2p⁶3s²3p⁶

10. They all have the same number of valence electrons (1). It is the valence electrons that are primarily responsible for the chemical properties of the elements.

Key for test 3.

1. Na⁺ and Br^-

Fe²⁺ and SO₃^2-

Ba²⁺ and NO₃^-

Mg²⁺ and F^-

2. C: 4, O: 2, Cl: 1, N: 3, H: 1 (this is very important!)

3. can't really draw on here. See you corrected tests.

4. K(one dot) O(6 dots), Cl(7 dots), N(5 dots), I(7dots)

5. NH₃: 8, O₂: 12, PO₄^3-: 32, N₂: 10

6. See you corrected test.

7. Most polar is C-O

8. CO₂ does not have a lone pair on the C atom whereas SO₂ does end up with a lone pair on the S atom. The lone pair repulsion causes the SO bonds to be bent away from the lone pair.

9. CO: nonpolar covalent, Br₂: covalent, CsCl: ionic, HCl: polar covalent

10. NaF is sodium fluoride, BaCl₂ is barium chloride, KI is potassium iodide, Fe(OH)₂ is iron(II)hydroxide

11. Potassiium bromide is KBr, lithium sulfate is Li₂SO₄, ammonium bisulfite is NH₄HSO₃, silver carbonate is AgCO₃.

Key for Test 4

1. Fe(OH)₂: 89.862, NO₂: 46.0055, KCl, and MgSO₄: 120.368

2. 13.896 Moles of Mg²⁺, 161.02 Grams of NO₂, and 1.67 x 10²¹ molecules of water.

3. a. 4Al + 3O₂ --> 2Al₂O₃

b. CH₄ + 2O₂ --> CO₂ + 2H₂O

c. 2C₄H₁₀ + 13O₂ --> 8CO₂ + 10H₂O

4. 0.1088 moles of H₂

5. C₆H₆ is the limiting reagent and 121 grams of C₆H₅Br

6. 33.4 g theoretical yield and 85.9 percent yield

7. a.) ions are Ba²⁺, NO₃^-, K⁺, SO₄^2-

b.) Ba²⁺ + SO₄^2- --> BaSO₄

8. a.) Pb is oxidized and Ag is reduced

b.) Ag⁺ is the oxidizing agent and Pb is the reducing agent

9. a.) This reaction is endothermic

b.) this reaction is exothermic

10. 88.9 grams of iron can be produced

Key for Test 5 1. 6.2 liters

2. 0.0746 liters

3. 4.00 gms/mol

4. 0.0932 liters

5. The first is NH₃, the second is HCl, the last is C₁₀H₁₈O₂

6. HF

7. No. Only water. Intermolecular hydrogen bonding is very important. Be sure to understand how two molecules can have such a bond.

8. CH₄ because of lower intermolecular forces.

9. 0.000632 gms/cm³

10. See book for picture.

Key for Test 6

1. P decreases, solubility decreases; T increases, solubility decreases

2. CH₃OH

3. increase

4. -5.25 ^oC

5. a.) absorbs water from air b.)water molecules in a crystal c.) compound in water leads to ions that will conduct electricity
d.) crystal without its water.

6. 2.68 M

7. The w/v percentage is 0.06

8. The w/v percentage is 0.23 and the Molarity is 0.054

9. 3.69 x 10⁴

10. 1.17

Key for Test 7

1. Rate is 6.14 x 10^-3 mol/Lmin

2. increase concentration of reactants, increase T, add catalyst

3. burning paper and taking this test!

4. a.) K =[H₂O]²][O₂]/[H₂O₂]²

b.)K = [HI]²/[H₂][I₂]

5.4.5 x 10⁸, 32, 4.5

6. 3.2 x 10^-3, 3 x 10^-7

7. a.)right, b.) left, c.) right, d.) left, e.) no shift

8. yes, T change

9. 0.0256 M

10. See book

Key for Test 8

1.

Acid Monoprotic Diprotic Triprotic amphiprotic

H2PO4- Yes yes

HSO3- yes yes

HClO4 yes

HSO3- yes yes

HBO32- yes yes

HS- yes yes

Acid	Monoprotic	Diprotic	amphiprotic
H2PO4-		Yes	yes
HSO3-	yes		yes
HClO4	yes
HSO3-	yes		yes
HBO32-	yes		yes
HS-	yes		yes

Note that all but HClO4 can accept a proton as well as donate a proton.

2. a.) HSO4-, b.) HS-, c.)I-, HS-

3.

pH [OH-] pOH

2 10^-12 12
12 10^-1 2
5 10^-9 9

pH	[OH-]	pOH
2	10^-12	12
12	10^-1	2
5	10^-9	9

4. a.) a buffer is a solution that will resist a change in pH when additional acid and/or base is added to the solution. It is made of an acid and its conjugate base.

b.) The buffer capacity is the max amount of acid or base that can be added to the buffer whithout a corresponding change in pH or pOH.

c.) 7.35

5. pH = pKa of formic acid since they are in equal molar amounts.

6. H3PO4 has a molecular weight of 98 and it has 3 protons so the EW is 98/3 = 32.7 and then 0.2 eq will be 0.2*32.7 = 6.54

7. Ba(OH)2 has a MW of 171.3 and it has 2 OH groups so the eq wt is 85.7 and then we determine that 3.4 g is 0.397 eq (3.4g/85.7g/eq). The normality is then .0397eq/.450L = 0.088

8. a.) There is only one H atom, so 3.0 M = 3.0 N

b.) There is only one OH group, so 0.34 M = 0.34 N