500.0 mL of 0.140 M NaOH is added to 565 mL of 0.250 M weak acid (Ka = 8.39 × 10-5). What is the pH of the resulting buffer?

HA(aq)+OH^-(aq)=H2O(l)+ A^-(aq)

pH=?

The following takes place in a voltaic cell:
Zn(s) + Cu2+(1 M) → Cu(s) + Zn2+(1 M).
The cell has a voltage of +1.10 V.
Choose the answer that best relates to
questions 1-4.
(A) there is no change in the voltage
(B) the voltage becomes zero
(C) the voltage increases
(D) the voltage decreases, but stays
positive
(E) the voltage becomes negative
1. What happens to the voltage when a
saturated ZnSO4 solution is added to
the zinc compartment of the cell?
2. What happens to the cell voltage
when the copper electrode is made
smaller?
3. What happens to the cell voltage
when the salt bridge is filled with
deionized water instead of 1 M
KNO3?
4. What happens to the cell voltage
after the cell has operated for 10
minutes?

Could you please explain why?

A 500 mL buffer is usually prepared with 46 mM carbonic acid and 58 mM sodium bicarbonate. Unfortunately you have run out of these reagents; on hand you have the following: solid citric acid, disodium maleate (salt of maleic acid), benzylamine and hydrochloric acid. Which reagent(s), and how much of each, would you need to use to produce a 500 mL buffer with the same formal concentration and pH as the carbonic acid buffer

I calculated the original pH of the solution to be 6.452 and the original amount of moles to be 0.052.

What I'm stuck on is how to properly make a buffer without a strong conjugate for the colution

What problems can occur if the iodine value of a starting material is too low? And too high ?

Which of the following amino acids pairs would form the described hydrogen bond at pH 7? Explain your answer?

A. His Asp

B. Tyr His

C. Ser Arg

D. Glu Thr

A certain protein has a molecular weight of 250 kD. What is the approximate number of amino acids residues?

A. 2

B. 750

C. 1200

D. 2300

E. 27500

Identify the bonding in each of the following substances as ionic or covalent.

The odor of a dead fish is attributed to trimethylamine, (CH3)3N, one of a series of compounds of nitrogen, carbon, and hydrogen with a general formula of (CH3)_nNH_3-n where n = 0-3 (the n = 0 compound is ammonia).

a) The Kb of trimethylamine [(CH3)3N)] is 6.5E-5 at 25 C. Calculate the pH of 3.00nE-4 M solution of dimethylamine.

b) The Kb of mythylamine [(CH3)NH2] is 4.4E-4 at 25 C. Calculate the pH of 2.88E-3 M solution of mythylamine.

c) the Kb of dimethylamine [(CH3)2NH] is 5.9E-4 at 25 C. What concentration of dimethylamine is needed for the solution to have the same pH as the solution in part B?

(Combustion Analysis)

100 m3 of a fuel oil are burned per hour with 20 percent excess air in a steam generator. The fuel oil has a density of 926 kg/m3 and the following mass composition: 87% C, 12% H2, 1% S. Air enters the boiler at 100 kPa and 15 °C. Determine the following:

(a). The volumetric flow rate of the air (m3 /min) fed to the boiler;

(b). The flue gas molar composition on a dry basis, reporting all constituents to the nearest 0.001% and assuming complete combustion of the fuel oil; and

(c). The dew point temperature (°C) of the combustion flue gas, if the pressure exiting the boiler stack is 200 kPa.

(d). The mass flow rate of sulfur dioxide (SO2) emitted from the boiler, in metric tons per day, assuming complete combustion of the fuel oil.

Calculate the pH and pOH for the following solutions:

a) 0.0450 M NaOH

b) 0.160 M Ca(OH)2

c) a 1:1 mixture of 0.0125 M HCl and 0.0125 M Ca(OH)2

d) a 2:3 mixture of 0.0125 M HNO3 and 0.0125 M KOH

One of the main assumptions in protein X-ray crystallography is, that proteins (for that matter all other biological macromolecules as well) in their crystalline state have folding topologies identical to those of the proteins in solutions or in their natural cellular environment. Several lines of evidence support this notion. Which one of the following is the most compelling to you? (Rate A trough F from most to less compelling and give your reasoning.

A) Except in some isolated cases, the structures of the same protein determined by X-ray crystallography and NMR methods are similar.

B) A crystalline protein can be essentially considered as in solution, because the solvent molecules, e.g. hydration water and solutes co-crystallize with the protein.

C) Proteins are generally resistant against unwanted side effects when subjected to the X-ray irradiation; therefore they maintain their overall physical state.

D) Enzymes usually retain their catalytic activity in the crystalline state.

E) Electron density maps can be obtained at high, atomic resolution and assigned with high accuracy.

Distilation questions

What is the function of the water in a steam distillation of the spice oil from the ground spices?

What determines the distillation temperature of the distillate in a steam distillation and why does it stay constant ?

Consider the following reaction and its equilibrium constant:

I2(g) + Br2(g) 2 IBr(g) Kc = 1.1 × 102

This reaction mixture contains initially 0.41 M I2 and 0.27 M Br2. Calculate the equilibrium concentration of I2, Br2, and IBr?

Please help with this, Can I find a example similar to this anywhere. I can't figure out some of the parts of this problem.

Who do you figure out alkalinity in chemisty?

Consider the two Lewis structures given below. Which of the following statements is correct?

In a reaction, 1 would function as a Lewis base while 2 would function as a Lewis acid.

2 would have similar Lewis acid-base properties as AlCl3.

1 can be classified as both a Brànsted-Lowry and a Lewis acid.

2 can be classified as both a Brànsted-Lowry and a Lewis base.

(a) How many moles of ammonium ions are in 0.795 g of ammonium carbonate?

(b) What is the mass, in grams, of 0.0507 mol of iron(III) phosphate?

(c) What is the mass, in grams, of 3.98*10^23 molecules of aspirin, C9H8O4?

(d) What is the molar mass of a particular compound if 0.090 mol weighs 6.38 g?