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# Physical Chemistry

### Buffers in Living Creatures

What is a buffer? Can you provide examples of buffers that operate in living creatures?

### Temperature that Favors Exothermic Reactions

What kind of temperature condition will favor the production of products in an exothermic reaction? Explain.

### Calculate the Total Cell Number

You are given a 500ml culture of Euglena from which a 1 ml sample is taken and put in 49 ml of water. Absorbance was measured on this sample but the reading was off the scale. One ml of this solution is taken and diluted in another 249 ml of water, and this time the OD675nm gave the reading of .27. If the turbidity of .27 corres

### Argon Gas Specific Heat and Conduction Bands

3. Argon gas is composed of point atoms and oxygen gas is composed of linear molecules of the form O---O where O denotes an oxygen atom. Determine the ratio of the specific heats at constant volume for these two gases. 4. Describe two different ways by which electrons can move from the valence band to the conduction band.

### Ideal Gas Law Questions

3. How is the ideal gas law modified to account for the finite volume of molecules? 4. The temperature of the sea bed 60 m below the surface and at the surface are both 20C. A rubber balloon is inflated at the sea bed with 2.0 mole gas neglecting the works done on the rubber determine: i)the volume of the balloon at the se

### Gas Law State Assumptions

1.a) state the assumption associated with the model used to develop the Ideal Gas Law b) hence or otherwise describe under which physical conditions does the ideal gas law applies 2. Explain why hydrogen which has one electron in its lowest state, should in principle be a metallic conductor in its solid state whereas heli

### Molecular Scale Mixing of Gas

A gas has a diffusion coefficient of 3*10^-5m^2s^-1. Use this information to compare how long it will take to obtain molecular scale mixing of such a gas over the following distances: i) 1*10^-4 m and ii) 10m.

### Chemical: Gas-Related Problems

6. A gas operates under isothermal conditions. The initial volume of gas in the pump is 22.4 liters, the pressure is one atmosphere and temperature is 273 deg K. if 0.6 mole of gas is released and the volume remains unchanged calculate the new pressure. 7. Calculate the minimum energy a photon must have to produce an electr

### Volume of the Gas in the Cheetos

The gas in a sealed bag of Cheetos? has a volume of 500 mL in Pueblo where the atmospheric pressure is 600 mm of Hg. You take this bag to the top of Pikes Peak where the pressure is 420 mm of Hg. Assuming the temperature on the Peak is the same as Pueblo (hot day on the Peak!), what is the volume of the gas in the Cheetos? bag o

### Buffer solution problem and problem using Henderson-Hasselbalch (H-H) equation

13. What is the pH of a solution prepared by mixing 50.00mL of 0.10 M NH3 with 25.00mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb= 1.8 x 10 -5 for NH3. 14. What is the pH of a solution made by mixing 30.00mL of 0.10M acetic acid with 30.00mL of 0.10 M KOH? Assume that the volumes of the

### Oxidation and Reduction in Standard Conditions

At standard conditions indicate whether each of the following is true. Explain for each A. Pb(s) can reduce NI2+ b. Hg2 2+( aq) can reduce Cu2+ n(aq) c. H+ (g) can oxidize Sn(s).

### Can Lead Reduce an Ion?

Is the following true in standard conditions? Pb(s) can reduce NI2+

### Weight and volume conversions to moles

How many moles are in each of the following? a. 33 g of acetylferrocene b. 10 mL of acetone c. 5 mL of water (the molecular weight of water is 18) d. 25 mL of hydrochloric acid (conc.)

### Hydrogen phosphate buffer system

Please help with the following problem. Buffer solutions have the unique ability to resist changes in PH when an acid or base is added to them. One important buffer system that helps to maintain blood pH at a constant value of 7.4 is the hydrogen phosphate buffer. The chemical equation for this for this buffer system is: H2P

### What Favors the Reverse Reaction?

Consider the equilibrium represented by the following equation: Heat + H2O(l)<>H2O(g) in which T=373K, P=101kPa Which of the following will favour the reverse reaction? (a) The total volume of the system is increased. (b) Boiling water is added to the system. (c) Water vapour is removed from the system. (d) The sy

### Truth about Systems at Equilibrium

Consider a stoppered flask containing benzene, iodine, and air, which has reached equilibrium at 298K. Which one of the following statements concerning the system at equilibrium is true? (a) The pressure of the vapour phase is not constant. (b) Evaporation of the liquid continues. (c) The colour of the liquid phase will

### Reaction Mechanisms of Tin

For these reactions I need mechanisms like "with curly arrows" like I-I bonds breaking and what happens next: 1. Sn + 2I2 -> SnI4 (Ac2O,AcOH, reflux) 2. SnI4 + 2PPh3 -> (PPh3)2SnI4 (CHCl3) 3. SnI4 + (Me2SO)2 -> SnI4(Me2SO)2 (CH2Cl2)

### Diffussion controlled electrolysis

Diffussion controlled electrolysis proceeds on (a) planar and (b) spherical electrode under the conditions: n = 1, C = 1 mM, A= 0.04 cm^2, D = 1.5x10^-5 cm^2/s. Calculate the current (i) in both cases at t = 0.5, 1, 3, 10 sec. How long can the electrolysis proceeed before the current at the spherical electrode exceeds that

### Kinetics: Exchange Current Density

The symmetry factor Beta was determined to be 0.4 for an activation controlled Ag deposition process. At overpotential n = -0.400 V the current density was found to be j = -5.125 A/dm^2. What is the value of the exchange current density jo, and what will be the current density j [A/dm^2] at an overpotential of -0.003 V?

### Lewis Structures, Hybrid orbital

1. Draw the Lewis structure for OF2 (small 2 at bottom) What are its electron-pair and molecular geometries? decribe the bonding in the molecule in terms of hybrid orbitals. 2. Draw the Lewis structure for C1F 2 + (small s at bottom and small + at top) What are its electron-pair and molecular geometries? decribe the bonding i

### Writing Balanced Redox Equations

Write a balanced redox equation for the reaction S2O3^2-9aq)+Cl2(g) -> SO4^2- (aq) + Cl^- (aq) in both acidic and basic medium.

### exact potential difference in the concentration cell

What will be the exact potential difference in the following concentration cells? a) Ag/Ag+ (0.1 M) // (0.01 M) Ag+/Ag b) Ag/Ag+ (0.000001 M) // (0.00001 M) Ag+/Ag Show step by step please

### Calorimetry involving heat of solution of NaOH(s)

A lab experiment dealing with the properties of a coffee cup calorimeter was completed. One of the procedures involved measuring the temperature of 50mL water placed in a calorimeter for 3 minutes, and then adding NaOH(s) pellets and measuring the temperature for 4 more minutes. I have several temperature measurements, but I am

### Writing an equation for electrode reactions

Consider the electrode/water-based solution interface Pt/Ag+ (0.01M), Cd^2+ (0.01M), HClO4 (1M) . Write the equation (s) for the electrode reaction(s) that occur at applied potentials of: 1.4 V, 0.6 V, 0.2 V, and -0.5 V (NHE)

### States of Matter

A meteorological balloon of radius 1.0M at sea level and 20 degrees C. At it's maximum altitude the radius of the balloon is 3.0M and the temperature is -20 degrees C. Calculate the pressure inside the balloon.

### States of matter, cylinders

Ian eats too many mars bars. To try to get rid of the excess kJ's he exercises in the gym by using a weights machine which works by compressing a cylinder of gas. If a standard mars bar is approximately 1000kJ. Calculate the number of times Ian has to push the piston in the cylinder up and down to 'burn off' a mars bar. Assume

### H2O yield in mL from Na2CO3 + 2HCl

I have worked this problem many different ways and cannot seem to set it up correctly. Na2CO3 + 2HCl => 2NaCl + CO2 + H2O I have 36.53g of sodium carbonate reacting with 32.94g of hydrchloric acid. I am trying to find how many mL of water are produced from this reaction.

### Electrochemistry and concentration

1. a) A copper refining cell is operating with an electrolyte which contains 0.05 m Sn2+. At what concentration of Cu2+ will the tin start to plate out in preference to the copper? The cell temperature is 40°C. b) A polarization potential arises from a concentration difference between ions in the neighborhood of the el

### Gas density calculations

A gas was found to have a densitiy of .08747 mg/ml at 17.0 degree C and a pressure of 76o torr. What is its molecular mass? What type of gas most likely is this?

### Lasers and gas mixtures

A certain laser uses a gas mixture made up of 9.00 g HCL, 2.00 g H2, and 165.0 g Ne. What pressure is exerted by the mixture in a 75.0 L tank at 22 degree C? Which gas has the smallest partial pressure?