An enzymatic reaction takes place in a 10 ml solution that has a total citrate (plus citric acid) concentration of 120 mM and an initial pH of 7.00. During the reaction 0.2 millimoles of H+ are produced. The relevant pKa of citric acid is 6.40. A) Calculate the final pH of the solution. B) What would the final pH of the solution be if the citrate were absent from the solution and no other buffering agents were present (assuming a starting pH of 7.00 again, basically, what would be the pH is you added the same amount of acid to that amount of water)?
In: Chemistry
In a titration of a 250mL solution of 0.05M ammonia (NH3) (Kb=1.8 * 10^-5) with a concentrated (0.2M) solution of HCL, calculate the following:
1. What is the initial pH before adding HCL?
2. What is the pH of the system after adding 20mL of the 0.2 M HCL?
3. What is the pH at equivalence?
*I have the answers, I really need to know how to do the work to get to the answers.*
In: Chemistry
The diffusion coefficients for species A in metal B are given at two temperatures: T (°C) D (m2/s) 1040 6.22 × 10-17 1280 6.11× 10-16 (a) Determine the value of the activation energy Qd (in J/mol). Entry field with incorrect answer 1.04e5 J/mol (b) Determine the value of D0. Entry field with incorrect answer 3.71e-22 m2/s (Use scientific notation.) (c) What is the magnitude of D at 1160°C? Entry field with incorrect answer 3.69e-18 m2/s (Use scientific notation.)
In: Chemistry
12. Predict the direction of the equilibrium shift when temperature is decreased in the following reactions:
a. C2H2 (g) + H2O (g) ? CH3CHO (g) [?H = -151 kJ/mol]
b. CH3CH2OH (l) + O2 (g) ? CH3CH2O (g) + H2O (g) [?H = exothermic]
c. 2 CH3CHO (g) ? 2 C2H4 (g) + O2 (g) [?H = endothermic]
13. Consider the following endothermic reaction for the production of hydrogen gas in a rigid container:
CH4(g) + H2O(g) ? CO(g) + 3 H2(g)
How will the yield of hydrogen change if the equilibrium is disturbed by:
a. Adding a catalyst.
b. Increasing the pressure.
c. Decreasing the temperature.
d. Adding inert argon gas.
e. Increasing the temperature.
In: Chemistry
Electrochemistry - Standart Potential
1. For the voltaic cell shown, calculate the Eocell.
| St. Red. Pot. (V) | ||
|
||
|
Hg(l), Hg2Cl2(s) l Cl-(aq) ll
Cu2+(aq), Cu+(aq) l Pt(s)
2. Calculate the standard emf for a voltaic cell whose cell reaction is represented by the balanced equation.
| St. Red. Pot. (V) | ||
|
||
|
Pb(s) + Zn2+(aq) → Pb2+(aq) + Zn(s)
3. For the galvanic cell shown, calculate the Eo.
| St. Red. Pot. (V) | ||
|
||
| F2/F-2.87 |
Au(s) l AuCl4-(aq), Cl-(aq) ll
F2(g) l F-(aq) l Pt(s)
In: Chemistry
Vitamin B12 was used in a column chromatography
experiment as a marker to show when all of the protein had eluted
off the column. Will vitamin B12 show up on the SDS-PAGE?
Explain.
In: Chemistry
A 29.6 mL sample of 0.260 M
diethylamine,
(C2H5)2NH, is
titrated with 0.338 M hydrochloric
acid.
After adding 33.7 mL of hydrochloric
acid, the pH is
.
Use the Tables link in the References for any
equilibrium constants that are required.
In: Chemistry
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?
In: Chemistry
A). A buffer solution is made that is 0.337 M
in H2CO3 and
0.337 M in
KHCO3.
(1) If Ka 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 Ka
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+.
In: Chemistry
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
In: Chemistry
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?
In: Chemistry
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?
In: Chemistry
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?
In: Chemistry
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!
In: Chemistry
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?
In: Chemistry