(a) What does the term population inversion refer to with respect to a laser and (b) why is population inversion required for light amplification to occur?

For each of the compounds described by the following names:

1. Draw a three-dimensional representation.

2. star(*) each chirality center.

3. draw any planes of symmetry.

4. draw any enantiomer.

5. draw any diastereomers.

6 label each structure you have drawn as chiral of achiral.

(a) (S)-2-chlorobutane

(b) (R)-1,1,2-trimethylcyclohexane

(c) (2R,3S)-2,3-dibromohexane

(d) (1R,2R)-1,2-dibromocyclohexane

Calculate the concentrations of all species in a .377M Na2CO3 solution [CO32-]= [Na+] = [OH-]= [H+]= [HCO-3]= and [H2CO3]= SHOW ALL WORK PLEASE

Radioactivity lab using equation age=1/k ln(1+D/P)

k=decay constant; D= # of daughter atoms in sample (beans); P= # of parent atoms in sample (M&M's)

if you found a container with 20 M&M's and 50 pinto beans, how old would you estimate the sample to be

what concentration of Zn^2+ will remain when 200mL of 4.50*10^-3 M Zn(NO3)2 is combined with 200.0mL of .250 M NaOH? Kf of Zn(OH)4 ^2- = 2.0*10^15

A buffer contains 0.10 mol of propionic acid (C2H5COOH) and 0.19 mol of sodium propionate (C2H5COONa) in 1.20 L.

Part A. What is the pH of this buffer?

Part B. What is the pH of the buffer after the addition of 0.02 mol of NaOH?

Part C. What is the pH of the buffer after the addition of 0.02 mol of HI?

1: Discuss the vaporization of water in standard condition at 298 K in term of: -1A exothermicity and endothermicity -1B change of entropy of the system and the surrounding -1C spontaneity of the reaction. ------ 2- Explain how the temperature and the composition of the two phases (liquid and vapour) influence the spontaneity of the vaporization of water. Please show steps and give ample explanation. Thank you

4. calculate the Eocell for the Ni - Al cell.

For the Ni - Al cell in question 4 write the following reactions
5. Cathode Half Reaction:
6. Anode Half Reaction:
7. Redox Reaction:
8. Using your answer from question 4, determine the Ecell for a Ni - Al cell when the concentration of Al3+(aq) is 4.00 M and the concentration of Ni2+(aq) is 2.00 x 10^-5 M.

Pure (100%) sulfuric acid has a density of 1.84 g/ml. How many mL of sulfuric acid need to be diluted with water to a total volume of 500 mL to prepare a solution with pH=0.500

Write the balanced half-reactions of the following types of batteries :(oxidation and reduction both)

a. Alkaline dry cell

b. Nickel-Metal Hydride battery

c. Zinc-air battery

d. Lead storage battery

Aluminum reacts with hydrochloric acid, but copper does not react with the acid. When a mixture of aluminum and copper having a mass of 0.3579 grams is combined with excess hydrochloric acid, 315.50 mL of hydrogen gas, measured over water, is generated. The temperature at the time of collection is 27.3 ^oC (vapor pressure of water at 27.3 ^oC = 27.214 torr), and the total pressure in the collection container is 764.1 torr. Determine the mass percentage of aluminum in the original mixture.

I've pretty much got my chem exam down for tomorrow, but I really need guidance for this question. Please show work and explain what you did (doesn't have to be so detailed).

A bomb calorimeter, or constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods. Since the "bomb" itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter. In the laboratory a student burns a 0.337-g sample of bisphenol A (C15H16O2) in a bomb calorimeter containing 1040. g of water. The temperature increases from 25.90 °C to 28.10 °C. The heat capacity of water is 4.184 J g-1°C-1. The molar heat of combustion is −7821 kJ per mole of bisphenol A. C15H16O2(s) + 18 O2(g) 15 CO2(g) + 8 H2O(l) + Energy Calculate the heat capacity of the calorimeter. heat capacity of calorimeter = J/°C

A standard SCUBA diving tank holds 10.9 L of compressed air at 204.1 atm. a. What are the mole fractions of N2 (Tc = 126.20K and Pc = 33.5 atm) and O2 (Tc = 154.4K and Pc = 49.7 atm) in air?

b. Determine how many moles of air are in this tank when filled, assuming the tank is at 25°C.

What is Taq Polymerase and why should it be used?