Problem Set 1 13 problems x 5pts each = 65pts .

1) For the following reaction:

3SnO4- + 4NO(g) +8H+ 3Sn+3 + 4 NO3- + 4H2O

What is being OXIDIZED

a) SnO4-b) NO(g)c)4H+d)Sn+2e)NO3-none

How many electrons are involved in the reaction

a) 3b) 5c) 15d) 10e) 12

2) What is the reducing agent in this reaction?

10I-(aq) + 2ReO4-(aq) + 16H+(aq) ---> 2Re2+(aq) + 5I2 + 8H2O(l)?

a) ReO4-b) I2c) Re+2d) I-e)H+f) none

(the reducing agent is I-; which itself is being oxidized)

3) A volume of 50.0 mL of 0.400 M HCl at 24.00°C is added to 100.0 mL of 0.200 M NaOH, at 27.00°C. After the reaction, the final temperature is 27.91°C. Calculate the enthalpy change, H, in kJ/mol for the following reaction:
HCl(aq) + NaOH(aq) --> NaCl(aq) + H2O(l)

Assume that the heat capacity of solution is the same as water 4.18J/g*T

BUT the final density of the solution is 1.02 g/ml

56.759.881.2061.0858.70none

=(50*24+27*100)/150 / 26.00 / Initial T
0.05*0.4 / 0.02 / moles of acid
0.1*0.2 / 0.02 / moles of base
4.18*150*1.02*(1.91) / 1221.5
=1221.5/0.02 / 61,076.07 / J/mole

4) An Aluminum cooking pot (mass =1150g; Cp= 0.9J/g*K) cools on the stove from 150 C to the boiling point of water 100C . What mass of water initially at 100 C could be vaporized to H2O(g) with the heat lost by the pot when it cooled (DHvap(water) = 2256 J/g)

q= Cp* m* T
q= 0.90*1150*(100-150) / -51,750 J
m = / q/ Hvap
Mass = / =51.75kJ/2.256 kJ/g = / 22.94 / g

5) The enthalpy of fusion of ice is 6.020 kJ/mol. The heat capacity of liquid water is 75.4 J/moloC. What is the smallest number of ice cubes at 0oC, each containing one mole of water, necessary to cool 420.0 ml of liquid water (assume density of one) initially at 34.1oC to 0oC?

Cp(l)* moles*(0-34.1) +Hf *x =0
= 0.0754*(420/18)*34.1/6.02 / 9.96 ~ 10 cubes

6) 1.13 L of pure water at 95.0 C is mixed with 130.0 g of ice at -50o C

What is the final temperature in Celsius of the mixture?

And How much more ice @ 0C would be needed to convert the total mixture completely to ice?

Hf / 334.72 / J/g
Cp(l) / 4.180 / J/g*K
Cp(s) / 2.006 / J/g*K

a) 26.2b) 2.46c) 74.5d) 76.9e) 82.7f) none

Cp(l)*ml (Tf-95) + Hf * ml + Cp(sl) ms *(Tf-0) + Cp(s) *ms *(0—50) =0
4.18*1130*(Tf-95) + 334.72*130 + 4.18*130*(Tf-0) + 2.006*130*(0- -50) =0
5266.8Tf / = / 392170

Impossible

7) How much energy would be released in the reaction of 50.0 GRAMS of METHANE to produce FORMALDEHYDE with an EXCESS of O2

Standard Molecular Enthalpies of Formation in kJ/mol

CH4 / -74.5 / CH3CH3 / -84.66
CH3OH / -200.9 / CH3CH2OH / -277.7
H2C=O / -108.6 / CH3-CH=O / -192.3
HCOOH / -378.6 / CH3COOH / -432.3
CO2 / -393 / H2O / -286

a)1180 kJb) 184 kJc) 640.2 kJd) 320.1 kJ e) 1000 kJf) none

2 CH4 / + O2 / ==> / 2 CH3OH / -401.8 / -149 / -252.8
2 CH3OH / + O2 / ==> / 2 H2C=O / +2H2O / -789.2 / -401.8 / -387.4
2 CH4 / + 2O2 / 2 H2C=O / +2H2O / -640.2

2 moles of methane would react with 2 moles of O2 to form 2 moles of Formaldehyde

Yielding

-252.8 / -387.4 / = -640.2kJ/ for this Rxn
50.0grams/16= / 3.125 moles of methane

(640.2kJ/ 2moles of methane in this reaction ) * 3.125 moles of methane = 1000.3 kJ

8) What is the minimum amount of oxygen in grams required for this reaction(methane going to formaldehyde) to occur?

33.3100.050.03.1251500.0

3.125 moles of methane require 3.125 moles of O2 === 3.125* 32g/mole =100 grams

9) What would be the Minimum Heat in kJ would be required to totally vaporize 100 ml of Mercury starting at 305 K?

Physical properties of Hg
Phase / Liquid
Density (near r.t.) / (liquid) 13.534 g·cm−3
Melting point / 234.32K
(-38.83°C, -37.89°F)
Boiling point / 629.88K
(356.73°C, 674.11°F)
Critical point / 1750 K, 172.00 MPa
Heat of fusion / 2.29 kJ·mol−1
Heat of vaporization / 59.11 kJ·mol−1
Specific heat capacity / 27.983 J·mol−1·K−1

923.0123.0460.468.29.15.04none

100ml*13.534g/ml= / 1353.4 / g
AW =200.59 / 6.75 /

moles

Heat to raise temperature to BP / 61,365.0 / J
=27.983*6.75*(629.88-305) / 61.37 / kJ
Heat to vaporize @BP / 399.0 / kJ
=59.11*6.75
Total Heat / 460.4 / k

10) Mixing 1.0M solutions of which two compounds will result in the formation of a precipitate

i)NH4NO3ii)NH4Briii)KBriv)Pb(NO3)2

iii and iv OR ii and iv OR BOTH (Give full credit for all three answers)

11) 30.0 mL of 0.8 M HCl, 100 mL of 0.25 M H2SO4 , and 60 ml of 0.8M Ca(OH)2 are combined. What is the pH of the final solution?

a) 13.1b) 12.0c) 0.6d) 1.98e) 12.02f) 2.70g) none

0.073 / Acid
0.096 / Base
0.023 / Excess Base in moles
0.12 / Concentration OH
0.94 / pOH
13.1 / pH

12) How much of which reagent would be needed to back titrate this solution to neutrality (pH=7.0)

27.5 ml / HCl
or
44.0 ml / Sulfuric

13) How many milliliters of 0.275 M Sulfuric Acid is required to neutralize 2.50 g of Calcium Hydroxide?

1222446133.776.4489none

2.5g/74.078 / moles of CaOH2 x 1moles H2SO4/1mole of CaOH2 = / 0.033748 / moles
0.03378moles / 0.125M = / 0.122 / L
122 / ml

Concept Multiple Choice Problems (2pts each)

1) Two metals of equal VOLUME but with different heat capacities and differing density are subjected to the same amount of heat. Which undergoes the smallest change in temperature?

a) Both undergo the same change in temperature.

b) The metal with the higher heat capacity.

b) The metal with the higher product of heat capacity*density

c) The metal with the lower heat capacity.

b) The metal with the smallest product of heat capacity*density

d) The metal with the smallest product of heat capacity/density.

e) You need to know the initial temperatures of the metals.

2) Which of the following do/does NOT have a standard enthalpy of formation equal to zero at 25oC and 1.0 atm?

a) CO2(g) b) Al(s) c) H2(g) d) Fe e) all have a standard enthalpy equal to zero.

3) Consider the reaction: 3H2(g) + N2(g)==> 2NH3(g) Ho = - 147 kJ

Which of the following is/are true?

a) The reaction is endothermic.

b) Heat is absorbed by the system.

c) The enthalpy of the productsare less than that of the reactants.

d) Ammonia is more stable than either hydrogen or nitrogen gas.

e)All are true.

4) If 2.0 kJ of energy is removed from a 15.5-g sample of water at 30.oC, the water is

a) completely vaporized. b) partially frozen solid.c) boiling.d) ionizedE) still a liquid but hotter.

5) Based on the activity series, which of the following reactions will occur?

(i)Al(s) + ZnCl2(aq) --->

(ii)AgCl(aq)+ Au(NO3)2(aq) --->

(iii)Co(s) + CrSO4(aq) --->

a) ii onlyb) i and iic) alld) i onlye) i and iii

6) Based on the activity series, which reactions below will occur?

a) 2Al(s) + 3Mg(s) ---> 2Al+3(aq) + 3Mg+2(aq)

b) 2Cu(s) + 2HI(aq) ---> 2CuI(aq) + H2(g)

c) ZnI2(aq) + 2HI(aq) ---> Zn(s) + H2(g) +2I-

d) Hg(s) + H2SO4(aq) ---> HgSO4(aq) + H2(g)

e) MgCl2(aq)+ 2HCl(aq) ---> Mg(s) + H2(g)

f) none

8) Which statement(s) is correct regarding oxidation?

a) Oxidation is always accompanied by reduction.

b) Oxidation is an decrease in positive charge.

c) Oxidation is a "loss" of protons.

d) Oxidation is associated with an increase in oxidation number of the reducing agent

e) none of these

f) all

9)An aqueous solution contains a Ni2+ salt. Based on the activity series, which of the following metals would not cause the precipitation of nickel metal when a strip of that metal is placed in the nickel solution?

a) cobaltb)magnesiumc) zincd) tine)chromiumf) none

10) Which of the following transitions in the Bohr hydrogen atom model affords absorption of the lowest-energy photon?

E(photon)= -2.18e-18*(1/nupper)2 –(1/nlower)2J/atom

ni = 1 --> nf = 6

ni = 4 --> nf = 3

ni = 5 --> nf = 4

ni = 3 --> nf = 6

ni = 3 --> nf = 4

Free Response Questions (4pts each)

1) You are given a 3.215 M Solution of Ammonium Phosphate and asked to make up 500 ml of 0.45 M Solution in Phosphate. How you would proceed:

Deliver 70.0 ml of 3.215M Ammonium Phosphate and dilute to 500ml

Deliver 75.0 ml of 3.0M Ammonium Phosphate and dilute to 500ml

2) You just get a new job after graduation in the lab and you are asked to prepare a 6.0 nM solution of Phosphate from the above 0.45M solution. Using dilution methods describe how you might proceed. You have at your disposal a dial-able micropipet that can deliver volumes from 1.000 to 0.001 ml. and you have a 100ml volumetric.

3) Arrange the following four elements from biggest to smallest Antimorny, Lead,Fluorine,Sulfur

Pb>Sb>S>F

4) Fill in the missing values

nm / λ meters / Frequency ()
RED / 750
YELLOW / 570
BLUE / 4.30x 10-07
UltraViolet / 4.00x 10+15
X-rays / x / 2.20x 10-09
x
Infrared / x / 1.50x 10-03
Microwave / 3.50x10+08

5) Draw a ground-state orbital diagram for Nitrogen which violates BOTH Hund's rule and the Pauli-exclusion Principle.

6) Both Chromium and Copper are exceptions to the general orbital occupancy rules, what might their electronic structure be and what factors are responsible for these special configurations

7) What is the electronic configuration for Lead

8) What is the electronic configuration for Europium (Eu)

9) If the Rydberg constant had been different, what might have been the impact on the DEVELOPMENT of quantum mechanics.

10) Name three experiments that supported that electron energies in atoms/molecules are quantized.

11) Discuss how the DOUBLE SLIT EXPERIMENT relates to the Heisenberg Uncertainty Principle (You must be detailed using labeled illustrations and equations)

12) The atomic size of an atom or ion is based upon a battle between which TWO primary forces, which turns out to be stronger and why?