Senna

If you think carefully about what happens during the course of a weak acid-strong base titration, you can learn some very interesting things. You can figure out the pKa of a weak acid just by thinking about the definition of Ka and looking at the right place on the titration curve! Which of the following choices is the best way to do this?

1.At the equivalence point, pH=pKa.

2.Halfway to the equivalence point, pH=pKa.

3.Before any base is added, pH=pKa.

4.At the top of the graph with excess base added, pH=pKa.

Titration of a strong acid with a strong base. The pH curve for titration of 50.0 mL of a 0.100 M solution of hydrochloric acid with a 0.100 M solution of NaOH(aq). For clarity, water molecules have been omitted from the molecular art.

What volume of NaOH(aq) would be needed to reach the equivalence point if the concentration of the added base were 0.200

Find Ka for HOCl in the appendix C, and then calculate Kb for OCl−.

The value of pKa for formic acid (HCO2H) is 3.74. What is the value of pKb for the formate ion (HCO−2)?

Any help is appreciated. Thank you! :)

Ammonia, NH3, is a weak base with a Kb value of 1.8×10−5.

What is the pH of a 0.300M ammonia solution?

What is the percent ionization of ammonia at this concentration?

Any help is appreciated! I dont understand how to do these. Thank you! :)

Please help! I dont understand how to do this problem. Thank you! :)

At 1000 K, Kp = 19.9 for the reaction Fe2O3(s)+3CO(g)⇌2Fe(s)+3CO2(g).What are the equilibrium partial pressures of CO and CO2 if CO is the only gas present initially, at a partial pressure of 0.974atm ?

dimerization of NO2 predictions?

Any help is appreciated!

2NO2(g) R N2O4

Predict the following of each of the following perturbations to this reaction:

A) increase in temperature

B) addition of inert gas

C) decrease in volume

D) addition of N2O4

Thank you!!

Please help! Thank you!

Any help is appreciated . Thank you! :)

Any help is appreciated!

2NO2(g) R N2O4

Predict the following of each of the following perturbations to this reaction:

A) increase in temperature

B) addition of inert gas

C) decrease in volume

D) addition of N2O4

Thank you!!

Any help is appreciated. Thank you (:

Consider the following multistep reaction:

A+B→AB(slow)

A+AB→A2B(fast)

−−−−−−−−−−−−−−−−

2A+B→A2B(overall)

Based on this mechanism, determine the rate law for the overall reaction.

Any help is appreciated :)

1. Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 year . How long will it take in years for 45.0 {\rm \\%} of Am-241 sample to decay?

2. A fossil was analyzed and determined to have a carbon-14 level that is 80{\rm \\%} that of living organism. The half-life of C-14 is 5730 years. How old is the fossil?

Thank you! :)

value of the rate of constant k?

For the reaction A+B+C→D+E, the initial reaction rate was measured for various initial concentrations of reactants. The following data were collected:

Trial [A] [B] [C] Initial rate

1 (M) (M) (M) (M/s)

2 0.20 0.20 0.20 6.0x10^-5

3 0.20 0.20 0.60 1.8x10^-4

4 0.40 0.20 0.20 2.4x10^-4

5 0.40 0.40 0.20 2.4x10^-4

What is the value of the rate constant k for this reaction?

Please help with any of these. I appreciate any help/explanations. Thank you! :)

1. An unknown radioactive substance has a half-life of 3.20hours . If 32.1g of the substance is currently present, what mass A0 was present 8.00 hours ago?

Molecular iodine, I2(g), dissociates into iodine atoms at 625 K with a first-order rate constant of 0.271 s−1.

If you start with 7.0×10−2M I2 at this temperature, how much will remain after 7.68s assuming that the iodine atoms do not recombine to form I2?

Half life is 2.56

Find the first and second derivatives please.

R=(1/(4s^3))-(8/(5s^4))

Please help. Thanks (:

T shirt printers?

Hi, I'm trying to start printing t shirts. I know there are many different types of printing styles, printers, etc. But i want to know what printers or methods are best. I want them to be high quality (vinyl vs. screen printing) and what's the best clamshell heat press machine to use. Also, can the machine fit shirts up to 3-4XL? Thank you.

calculus? limits help?

How do you find the limit of

Limx-> -0.5+ Sqrt((x+14)/(x+5))

Thank you!

How do you find the limit of

Limx-> -0.5+ Sqrt((x+14)/(x+5))

Thank you!

limits - table. calculus help?

I don't know how to enter this in the calculator. Please help!

Let f(x)=

5^x−1

--------

x.

a. Make tables of values of f at values of x that approach x0=0 from above and below. Does f appear to have a limit as x→0? If so, what is it? If not, why not?

b. Support your conclusions in part (a) by graphing f near x0=0.

a. Complete the table of values of f at values of x that approach x0=0 from above.

x:

0.1

0.01

0.001

0.0001

0.00001

0.000001

f(x):?

(Round to six decimal places as needed.)

Thank you!