Iconic memory is a type of memory that holds visual information for about half a second (0.5 seconds). To demonstrate this type of memory, participants were shown three rows of four letters for 50 milliseconds. They were then asked to recall as many letters as possible, with a 0-, 0.5-, or 1.0-second delay before responding. Researchers hypothesized that longer delays would result in poorer recall. The number of letters correctly recalled is given in the table.

(a) Complete the F-table. (Round your values for MS and F to two decimal places.)

(b) Compute Tukey's HSD post hoc test and interpret the results. (Assume alpha equal to 0.05. Round your answer to two decimal places.)

The critical value is  for each pairwise comparison.

Which of the comparisons had significant differences? (Select all that apply.)

Recall following no delay was significantly different from recall following a one second delay.The null hypothesis of no difference should be retained because none of the pairwise comparisons demonstrate a significant difference.Recall following a half second delay was significantly different from recall following a one second delay.Recall following no delay was significantly different from recall following a half second delay.

1. In order to determine the size of a home-heating furnace, it is necessary to estimate the heat loss during the coldest day in winter. Provide the rates of heat loss per unit surface area for the following surfaces commonly encountered in house construction. You may assume an inside air temperature of 25°C, an outside temperature of -5°C, and heat transfer coefficients of 20 Wm-2K-1 and 5 Wm-2K-1 between air and the outside and inside surfaces, respectively. The thermal conductivities of glass and air are 1.4 and 0.026 Wm-1K-1, respectively.

a. A 3 mm-thick single-pane glass window.

b. A double-pane glass window consisting of two 3 mm-thick panels separated by a 6 mm-thick layer of stagnant air.

c. A composite wall consisting of a 10-cm-thick brick exterior (k = 1.0 Wm-1K-1), a 10-cm-thick layer of loosely packed glass fiber insulation (k = 0.043 Wm-1K-1), and an inside gypsum plaster wall (k = 0.17 Wm-1K-1) that is 1 cm thick.

d. Workmen installing a wall of the design described in part (c) are asking for a premium to install a vapor barrier on the plaster wall to prevent moisture from diffusing out of the house and condensing in the glass fiber insulation. If the dew point of the moist air in the house were 10°C would you pay the premium? Why?

Iconic memory is a type of memory that holds visual information for about half a second (0.5 seconds). To demonstrate this type of memory, participants were shown three rows of four letters for 50 milliseconds. They were then asked to recall as many letters as possible, with a 0-, 0.5-, or 1.0-second delay before responding. Researchers hypothesized that longer delays would result in poorer recall. The number of letters correctly recalled is given in the table.

(a) Complete the F-table. (Round your values for MS and F to two decimal places.)

(b) Compute Tukey's HSD post hoc test and interpret the results. (Assume alpha equal to 0.05. Round your answer to two decimal places.)

The critical value is _____ for each pairwise comparison.

Which of the comparisons had significant differences? (Select all that apply.)

Recall following a half second delay was significantly different from recall following a one second delay.

Recall following no delay was significantly different from recall following a one second delay.

Recall following no delay was significantly different from recall following a half second delay.

The null hypothesis of no difference should be retained because none of the pairwise comparisons demonstrate a significant difference.

Are cigarettes bad for people? Cigarette smoking involves tar, carbon monoxide, and nicotine (measured in milligrams). The first two are definitely not good for a person's health, and the last ingredient can cause addiction. Brand Tar Nicotine CO Brand Tar Nicotine CO Alpine Benson & Hedges Bull Durham Camel Lights Carlton Chesterfield Golden Lights Kent Kool L&M Lark Lights Marlboro Merit 14.1 16.0 29.8 8.0 4.1 15.0 8.8 12.4 16.6 14.9 13.7 15.1 7.8 0.86 1.06 2.03 0.67 0.40 1.04 0.76 0.95 1.12 1.02 1.01 0.90 0.57 13.6 16.6 23.5 10.2 5.4 15.0 9.0 12.3 16.3 15.4 13.0 14.4 10.0 MultiFilter Newport Lights Now Old Gold Pall Mall Lights Raleigh Salem Ultra Tareyton True Viceroy Rich Light Virginia Slim Winston Lights 11.4 9.0 1.0 17.0 12.8 15.8 4.5 14.5 7.3 8.6 15.2 12.0 0.78 0.74 0.13 1.26 1.08 0.96 0.42 1.01 0.61 0.69 1.02 0.82 10.2 9.5 1.5 18.5 12.6 17.5 4.9 15.9 8.5 10.6 13.9 14.9 Use the data in the table above to make a stem-and-leaf display for milligrams of nicotine per cigarette smoked. In this case, truncate the measurements at the tenths position and use two lines per stem. (Enter NONE in any unused answer blanks.) Milligrams of Nicotine per Cigarette

2

(a) ΔrG° for the following reaction at 398 K is 2.6 kJ mol−1:

H2(g) + I2(g) → 2 HI(g)

If a gas mixture containing: 2.00 bar of H2, 2.00 bar of iodine vapour, and 0.500 bar of hydrogen iodide, is sealed in a container at 398 K, is the reaction at equilibrium? [4]

(b) Sketch a graph to show how the conductivity of a solution varies with concentration depending on whether the solute is a strong or weak electrolyte. Include the equation which allows the limiting molar conductivity to be obtained from the graph.

Explain why the graphs are different. [4]

The following questions are concerned with electrochemical cells.

(c) If I2 and Br2 are added to a solution containing I– and Br– , what reaction will occur if the concentration of each species is 1M? Explain your answer. The standard reduction potentials of iodine and bromine are given below:

I2 + 2 e– → 2 I– E° = +0.54 V

Br2 + 2 e– → 2 Br– E° = +1.09 V [4]

(d)

Cu(s) | Cu2+(aq, 0.1 mol dm–3 ) || Ag+ (aq, 1.0 mol dm–3 ) | Ag(s)

Ag+ (aq) + e– → Ag(s) E° = +0.80 V

Cu2+(aq) + 2 e– → Cu(s) E° = +0.34 V

(i) Calculate E°cell under standard conditions. [2]

(ii) Calculate Ecell for the concentrations given in the cell diagram above. [4]

(iii) Calculate ΔG for the above cell. [2]

In this problem you will determine the amount of force a rider needs to exert on a bicycle pedal to accelerate at a rate of 1.0 m/s^2.

(c) Now consider the system consisting of the rear wheel. The system includes the sprocket (gear wheel) attached to it. Assume that the rear sprocket has a radius of 2.5 cm and neglible mass compared to the wheel. Assume that the rear wheel has the same mass, radius, and moment of inertia as the front wheel. The sprocket is driven by the bicycle chain. Assume that the tension in the upper portion of the bicycle chain is nonzero, neglect the tension in the lower portion of the chain. Write a free-body diagram for the system. By considering the torques on the system, find the tension in the chain.

(d) Now consider the system consisting of the crank, which means the front sprocket, and the pedals. The system is mounted on a frictionless axle. Assume that the pedals are a distance of 17 cm from the crack axle, that the front sprocket has a radius of 8.0 cm. Assume that the entire crank assembly has a moment of inertia 2.5 x 10^-2 kg m^2. Assume that the bike pedals are oriented horizontally, and that the rider is pushing straight downward on the forward pedal with a force F, with no force on the back pedal. Write a free-body diagram for the system. By considering the torques on the system, find the force F. Does your answer change if we neglect the moment of inertia of the crank?

(e) Is this a realistic force for a rider to exert on a bike pedal? If not, estimate the maximum acceleration you think is realistic for a bicycle.

1. Given the following information

   Ag⁺(aq) + e^- ↔ Ag(s)   Eº_red = 0.799 V

   Ag₂CrO₄(s) + 2e^- ↔ 2Ag(s) + CrO₄^2-(aq) Eº_red = 0.450 V

   Determine the equilibrium constant at 25 °C for the reaction below:

   Ag₂CrO₄(s) ↔ 2Ag⁺(aq) + CrO₄^2-(aq)

   	1.	9 × 10-18
   	2.	1.6 × 10-12
   	3.	1.2 × 10-6
   	4.	1.6 × 1015
   	5.	1.7 × 1039

1. Examine the following half reactions and select the strongest oxidizing agent among the species listed.

   Cr²⁺(aq) + 2e^- ↔ Cr(s) Eº_red = -0.913 V

   Sr²⁺(aq) + 2e^- ↔ Sr(s) Eº_red = -2.89 V

   Fe²⁺(aq) + 2e^- ↔ Fe(s) Eº_red = -0.447 V

   Co²⁺(aq) + 2e^- ↔ Co(s) Eº_red = -0.28 V

   	1.	Cr2+(aq)
   	2.	Fe(s)
   	3.	Fe2+(aq)
   	4.	Sr2+(aq)
   	5.	Co2+(aq)

2 points   

QUESTION 5

1. Which of the changes below will increase the voltage of the following cell?

   Co | Co²⁺ (0.010M) || H⁺ (0.010 M) | H₂(0.50 atm) | Pt

   	1.	Increase the pressure of H2 from 0.50 atm to 1.0 atm
   	2.	Increase the concentration of H+ from 0.010 to 0.050 M.
   	3.	Increase the mass of Co electrode from 12 grams to 15 g.
   	4.	Increase the concentration of Co2+ from 0.010 M to 0.40 M.

Molar Mass Determination by Depression of the Freezing Point

A student determines the freezing point of a solution of 0.630 g of mandelic acid in 20.78 g of tbutanol. He obtains the following temperature-time readings:

Plot these data using any spreadsheet or plotting program. Note that the first several points fall roughly on a straight line. The last several points fall on a different straight line. Perform linear regressions on these two lines to determine the freezing point of the solution (the temperature at which the lines intersect is the freezing point of the solution). Ignore the rather substantial supercooling that occurred. Attach a copy of the plot to this sheet.

What is the freezing point of the solution?

What is the freezing point depression, ÄTf ? (Tf = 24.5C for t-butanol.)

What is the molality, m, of the mandelic acid in the solution? (Use Equation 1.3, Kf = 8.09 C/m.)

What is the molar mass of mandelic acid? Use Equation 5.4 as rearranged below:

____________C

____________C

____________ m

_________ g/mol

5. The molecular formula of mandelic acid is C8H8O3. Is the result you obtained in Part e consistent with this formula?

11- The pH of a sodium acetate-acetic acid buffer is 4.70. Calculate the ratio [CH3COO−] / [CH3COOH].






1- Calculate the pH of a 0.20 M NH3/0.20 M NH4Cl buffer after the addition of 25.0 mL of 0.10 M HCl to 65.0 mL of the buffer.


A- Enter your answer in the provided box.

A 21.0−mL solution of 0.110 M CH3COOH is titrated with a 0.240 M KOH solution. Calculate the pH after the following additions of the KOH solution:

(a) 0.00 mL
=_____


(b) 5.00 mL
=_______


C- Enter your answer in the provided box.

In a titration experiment, 21.9 mL of 0.813 M HCOOH neutralizes 24.4 mL of Ba(OH)2. What is the concentration of the Ba(OH)2 solution?
_____M

D- a) Calculate the pH of the 0.39 M NH3/ 0.73 M NH4Cl buffer system.

pH =


(b) What is the pH after the addition of 20.0 mL of 0.075 M NaOH to 80.0 mL of the buffer solution?

pH =



E- What mole ratio would you need to prepare a liter of "carbonate buffer" at a pH of 9.96?


______: 1.0 : 0

A) NaHCO3 : H2CO3 : Na2CO3
B) Na2CO3 : NaHCO3 : H2CO3

Choose the order of the compounds that is represented in the numeric ratio.



F- Enter your answer in the provided box.

The pH of a bicarbonate-carbonic acid buffer is 6.18. Calculate the ratio of the concentration of carbonic acid (H2CO3) to that of the bicarbonate ion (HCO3−).
(Ka1 of carbonic acid is 4.2 × 10−7.)

[H2CO3]
[HCO3−]
=