Consider the diprotic acid H2X, where Ka1 = 1.75 x 10-5 and Ka2 = 4.3 x 10-12 at 25 °C. The concentration of HX- (aq) in a 0.125 M solution of H2X at 25 °C is approximately
E. none of these
In: Chemistry
The sulfur in a 5.00 g sample of steel was evolved as H2S and then collected in a solution of CdCl2 to produce the precipitate CdS. The CdS was then titrated with excess I2 and the remaining I2 was then back titrated with 4.82 ml of 0.0510 M sodium thiosulfate. If the concentration of the I2 is 0.0600 M and a total of 10.0 ml is added, calculate the %S in the steel.
The relevant reactions are:
CdS + I2 -> S + Cd2+ + 2I-
I2 + 2S2O3- -> S2O62- +2I-
In: Chemistry
2) (40 pts) An alligator that has been warming in the sun swims into cold water. Calculate the following parameters, if the alligator temperature (underneath the scales) is 33 °C and the water temperature is 15 °C. Assume the pathway for heat transport is through the thick scales (with conductance of 0.5 mol m-2 s -1 ) and then through a thin boundary layer in the water (with conductance of 1 mol m-2 s -1 ). Ignore radiative effects and view factor considerations, and assume there is no fluid movement, just diffusion (ie, no forced or free convection).
a) What is the total conductance to heat loss?
b) What is the convective heat loss in Watts per square meter?
c) Now imagine that a python swallows the alligator whole, and that the python has a resistance to heat loss of 3 m2 s mol-1 . What is the new total conductance of the alligator-python combination to heat loss? (hint – this just adds a third series element to the conductances – assume the boundary layer conductance still applies and does not change).
d) What is the new convective heat loss from the alligator to the water (through the python)?
e) How would your answer to c) change if the python’s resistance was a parallel combination of 3 m2 s mol-1 through the spots, and 15 m2 s mol-1 through the spot-free areas?
f) What is the convective heat loss in e)?
In: Chemistry
What is the oxidation number of the following elements when they form ions?
1. Se
2. Li
3. Al
4. P
In: Chemistry
Consider the following liquids with similar molar masses. Predict which has the weakest intermolecular attraction based only on boiling point data.
butane (Bp @ 760 mm Hg = -0.5 °C)
ethyl chloride (Bp @ 760 mm Hg = 12 °C)
propyl alcohol (Bp @ 760 mm Hg = 97 °C)
acetic acid (Bp @ 760 mm Hg = 118 °C)
ethyl methyl ether (Bp @ 760 mm Hg = 11 °C)
In: Chemistry
The heat of solution of potassium acetate
(KC2H3O2) in water is -15.30
kJ/mol.
If 19.70 g of KC2H3O2(s) is
dissolved in 600.0 mL of water that is initially at 24.50 °C,
What will be the final temperature (in degrees Celcius) of the
resulting aqueous solution?
(Assume no heat exchange with the surroundings.)
In: Chemistry
Consider the titration of 50.0 mL of 0.130 MHNO3 with 0.450 M NaOH.
How many millimoles of HNO3 are present at the start of the titration?
How many milliliters of NaOH are required to reach the equivalence point?
What is the pH at the equivalence point?
In: Chemistry
Describe the Applications, Reagents, and Procedure of the Southern blot technique. Add bibliography.
In: Chemistry
Describe the Applications, Reagents, and Procedure of the Western blot technique. Add bibliography.
In: Chemistry
23. KCN is insoluble in benzene but in the presence of 18-crown-6 the nucleophilic substitution reactions take place very fast using CNas nucleophile- Justify with mechanism.
24. Arylamines and heterocyclic aromatic amines are considerably less basic than alkylamines — Justify.
25. p-Anisidine is more basic than aniline — Justify with appropriate drawings.
In: Chemistry
What will the molarity be of the resulting solutions made by mixing the following? Assume that volumes are additive.
a)116 mL of 3.6 M H3PO4 with 776 mL of H2O
(b) 219 mL of 0.39 M Na2SO4 with 737 mL of H2O
(c) 75 mL of 0.50 M HNO3 with 75 mL of 1.5 M HNO3
In: Chemistry
A) A solution of Ba(OH)2 has a molarity of 0.00617 mol/L. Calculate the final pH of the solution.
B) Consider the reaction: CaBr2(s) → Ca(s) + Br2(l)
Which of the following statements is correct? Select all that apply.
Bromide Ion is reducing agent
NOT a spontaneous reaction
Ca is oxidized
Br is Oxidized
Br is Reduced
Ca is Reduced
Calcium Ion is the Reducing Agent
IS a spontaneous reaction
Br ion is the oxidizing agent.
Ca ion is the oxidizing agent.
C) What would cause the equilibrium to shift left CH3COOH(aq) + H2O(l) ⇌ CH3COO–(aq) + H3O+(aq).
Add HCL
pH increasing
Add acetic acid
Acetate Ion addition
D) 3 A2 (g) + 2 Z3 (g) ↔ 3
Z2A2 (g)
The equilibrium concentrations are: A2 = 0.061 mol/L ;
Z3 = 0.769 mol/L ; Z2A2 = 0.245
mol/L.
Calculate the value of the equilibrium constant at
345oC.
E)
Which of the following equations represents H2BO3− acid
|
H2BO3− (aq) + H3O+(aq) ⇌ H3BO3 (aq) + H2O(l) |
||
|
H2BO3− (aq) + HCO3−(aq) ⇌ HBO32−(aq) + H2CO3(aq) |
||
|
H2BO3− (aq) + H2S (aq) ⇌ H3BO3(aq) + HS−(aq) |
||
|
H2BO3− (aq) + H2O(l) ⇌ H3BO3(aq) + OH−(aq) |
||
|
H2BO3− (aq) + NH4+(aq) ⇌ H3BO3 (aq) + NH3(aq) |
In: Chemistry
Sketch a general Lineweaver-Burke plot that illustrates the kinetic behavior of a non-allosteric enzyme. Identify on your plot the features that allow one to determine Vmax and KM for the enzyme.
How would one use a Lineweaver-Burke plat of enzyme kinetic data to identify an inhibitor's mode of action?
In: Chemistry
For the following systems at equilibrium A:2NOCl(g)⇌2NO(g)+Cl2(g) B: H2(g)+I2(g)⇌2HI(g) classify these changes by their effect.
Drag the appropriate items to their respective bins.
Bins: leftward shift, no shift, rightward shift
Items: system A Decrease container size, system A Increase container size, system b Increase container size, system B Decrease container size
In: Chemistry