To resolve an object in an electron microscope, the wavelength of the electrons must be close in the diameter of the object. What kinetic energy must the electrons have in order to resolve a protein molecule that is 9.00nm in diameter? Take the mass of an electron to be 9.11 X10 ^-31

How many photons are produced in a laser pulse of 0.435 J at 449nm?

A). A buffer solution is made that is 0.337 M in H₂CO₃ and 0.337 M in KHCO₃.

(1) If K_a for H₂CO₃ is 4.20×10^-7, what is the pH of the buffer solution?  

(2) Write the net ionic equation for the reaction that occurs when 0.075 mol NaOH is added to 1.00 L of the buffer solution

B). A buffer solution is made that is  0.317 M in  H₂C₂O₄ and  0.317 M in  KHC₂O₄.  

(1) If K_a for  H₂C₂O₄ is  5.90×10^-2, what is the pH of the buffer solution?  

(2) Write the  net ionic equation for the reaction that occurs when  0.071 mol  HBr is added to  1.00 L of the buffer solution.  

Use H₃O⁺ instead of H⁺.

Magnesium sulfate has a number of uses, some of which are related to the ability of the anhydrate form to remove water from air and others based on the high solubility of the heptahydratc (MgSO.4 . 7H2,O)form, also known as Epsom salt. The densities of the anhydrate and heptahydratc crystalline forms are 2.66 and 1.68 g/mL, respectively. Suppose you wish to form a 20.0 wt% MgS()4 aqueous solution by simply pouring crystals of one of the forms into a tank of water while the temperature is held constant at 30degree C. The specific gravity of the 20.0 wt% solution at 30degree C is 1.22. Answer the following questions for both forms of the MgS04 crystals: What volume of water should be in the tank before crystals arc added if the final product is to be 1000 kg of the 20wt% solution? Suppose the tank diameter is 0.30 m. What is the height of liquid in the tank before the crystals are added? What is the height of the water in the tank after addition of the crystals but before they begin to dissolve? What is the height of liquid in the tank after all the MgSO4 has dissolved?5.8. Use the idcal-gas equation of state to kg/m3 at 40degree C

EAS//Nitration of bromobenzene

Brief summary of procedure.

- Mix sulfuric acid +nitric acid, then cool in water bath. Add stir bar, condenser and reflux for 10 minutes while slowly adding bromobenzene. Don't exceed 55 degrees celcius

- Heat mixture for 15 minutes below 60 degrees celcius. Cooldown, then pour into 40 mL of cold h2o

- vacuum filtration to isolate crude bromonitrobenzene

- recrystallize with 95% ethanol (cool to room temp, then to 0 degrees celcius on ice)

- isolate product by vacuum and wash with ice-cold 95% ethanol.

- concentrate mother liquor under reduced pressure solvent removal.

Suppose your lab mate wants to make 2,4-dinitrobromobenzene from bromobenzene using a variation of the proceduredescribed in the textbook.

a) What changes should your lab mate make to the procedure to maximizetheir yield of 2,4-dinitrobromobenzene? (1.5 point)

b) What is the minimum volume of 12.3M HNO3 that is required to make themost 2,4-dinitrobromobenzene from 3.8 mL of bromobenzene?

Many linear polymers can exhibit large amounts of deformation. Explain how the structure of this type of polymer changes as it undergoes loading to failure.

The type of polymer is linear. How do linear polymers change under loading?

At 800 K, the equilibrium constant, Kp, for the following reaction is 3.2 ´ 10-7. 2 H2S(g) f 2 H2(g) + S2(g) A reaction vessel at 800 K initially contains 3.50 atm of H2S. If the reaction is allowed to equilibrate, what is the equilibrium pressure of H2?

Use the data in Appendix B in the textbook to calculate the following quantities. (College Chemistry II)

Part A-

N2(g)+2H2(g)?N2H4(l) (Express your answer using one decimal place.)

1. ?H? for the following reaction?

2. ?S? for this reaction?

3. From the values of ?H? and ?S?, calculate ?G? at 25 ?C?

Part B-

CH3OH(l)+O2(g)?HCO2H(l)+H2O(l) (Express your answer using one decimal place.)

1. ?H? for the following reaction?

2. ?S? for this reaction?

3. From the values of ?H? and ?S?, calculate ?G? at 25 ?C?

Please show the works, and thank you so much!

Why is it important to avoid air bubbles when you pack columns for column chromatography? If you accidently introduce air bubbles into the columns, what are the strategies you could take to remove the air bubbles? When running the column, is it okay to run the liquid below the column level? Why?

An enzyme is discovered that catalyzes the chemical reaction

SAD --> <-- HAPPY

A team of motivated researchers set out to study the enzyme, which they call happyase. Under a constant enzyme concentration, [E] of 2.0 uM, they studied the relationship between substrate concentration [SAD] and reaction velocity V₀. Their data is shown below:

[SAD] (uM)                V₀ (uMs^-1)      

20                    3.4 x 10³

40                   5.4 x 10³

60                   6.6 x 10³

80                    7.4 x 10³

Can you determine K_cat and K_m from the above data?

2. While [E] remains 2.0 um and [SAD] = 12 uM, what would the reaction velocity V₀ be?

3. In a separate happyase experiment using [E] = 1.0 uM, the reaction velocity, V_0, is measured as 3.6 x 10³ uMs^-1. What is the [SAD] used in this experiment?

4.The researchers working on happyase discovered that the compound STRESS is a potent inhibitor of happyase. A kinetics study of happyase in the presence of         1 nM STRESS, gives the following data:

[SAD] (uM)                V₀ (uMs^-1)      

20                    1.7 x 10³

40                   2.7 x 10³

60                    3.3 x 10³               

80                    3.7 x 10³

Which class of inhibitors does STRESS belong to?

This is the substrate concentration and the kinetic slopes from lab experiment. I'm suppose to construct a graph to estimate Km and Vmax (that's where I need help. How do I do that? Also, I'm suppose to construct another graph of "linear transfored" plot (lineweaver-burk or Eadie-hofstee plots) to determine Km and Vmax. HELP!

use the following information to determine if the intermolecular forces of isopropyl alcohol are greater or weaker than the intermolecular forces of water? the melting point of iso alcohol is about -90c and the boiling point is about 82c.

B. What happens to heat energy when it is not increasing the temperature of the substance in the beaker?

C.What occurs to the particles of a substance when the substance melts. why does this occur?

Use the data found in the appendix to determine the values for the O-Cl and the O-F bond energies. (heats of formation of OF₂ and OCl₂ are 24.7 and 80.37 kJ/mol, respectively)

solution, mL dissolved rock
1.              10
2.               10
3.              10
4.              10
5.               10
                 mL 0.100M sodium metasilicate added
0
1.00
2.00
4.00
20.00
total volume
50
50
50
50
50
Si Signal (mA)
0.235
0.500
0.768
1.250
5.202
A 10.000g sample of rock containing quartz as the sole source of silicon is dissolved and diluted to 1.000 +/- 0.010 liters and analyzed by the method of standard additions. What is the wt% of quartz in the rock?

Determine the pH of a solution that is 0.025 M C2H8N2 where Kb(C2H8N2) = 8.3 * 10−5?

The reaction F + G = H is at equilibrium, under standard conditions.

(a) Calculate ∆Go’ if [F] = 2mM, [G] = 3 mM, and [H] = 9 mM

(b) What happens to ∆Go’ if the solution is at equilibrium at twice this concentration of F?

(c) What happens to ∆Go’ if the solution is at equilibrium at twice this concentration of H?

(d) Does this violate LeChatelier’s Principle?