A 4.50 mL sample of a 0.100 M solution of an aromatic hydrocarbon dissolved in hexane is excited with a flash of light. The aromatic compound emits 19.3 J of energy at an average wavelength of 379 nm. What percentage of the aromatic compound molecules emitted a photon? Please Help, Thanks

How many grams of sodium lactate (MW = 112 g/mol) are required to prepare 200 ml solution at 1.0 M? Given pKa of lactic acid = 3.86, what is the pH of this solution?

If the Kb of a weak base is 3.8 × 10-6, what is the pH of a 0.39 M solution of this base?

You are given a sample containing a hydrocarbon and an amine - both compounds are very insoluble in water and very soluble in diethyl ether. Describe how you could efficiently separate these two compounds using extraction methods; clearly explain why your procedure should give a good separation of the components (i.e., both compounds isolated in good yield and purity).

Calculate the pH during titration of 25 mL of 0.175 M HCN with 0.3 M NaOH after the addition of 0 mL, 7.29mL, 14.5833 mL, and 20 mL base. Kb of CN- is 2.03 x 10^-5. Show all work.

1)The data below were collected for the following reaction:
CH3Cl(g)+3Cl2(g)→CCl4(g)+3HCl(g)

A

Calculate the value of the rate constant, k.

Express your answer using two significant figures.

B

What is the overall order of the reaction?

Express your answer using two significant figures.

2)

What is the activation energy of this reaction?

Express your answer to three significant figures and include the appropriate units.

3)

The decomposition of XY is second order in XYand has a rate constant of 7.08×10⁻³ M−1⋅s−1at a certain temperature.

-

If the initial concentration of XY is 0.140 M , how long will it take for the concentration to decrease to 6.80×10⁻² M ?

Express your answer using two significant figures.

4)

The rate constant of a chemical reaction increased from 0.100 s−1 to 2.70 s−1 upon raising the temperature from 25.0 ∘C to 55.0 ∘C .

A"SOLVED"

B

Calculate the value of ln(k1k2) where k1 and k2 correspond to the rate constants at the initial and the final temperatures as defined in part A.

Express your answer numerically

C

What is the activation energy of the reaction?

Express your answer numerically in kilojoules per mole.

5)

The rate constant (k) for a reaction was measured as a function of temperature. A plot of lnk versus 1/T(in K) is linear and has a slope of−1.02×10⁴ K .

Calculate the activation energy for the reaction.

Express your answer with the appropriate units.

6)

Osmosis is the process responsible for carrying nutrients and water from groundwater supplies to the upper parts of trees. The osmotic pressures required for this process can be as high as 19.1 atm . What would the molar concentration of the tree sap have to be to achieve this pressure on a day when the temperature is 28 ∘C ?

At 1 atm, how much energy is required to heat 93.0 g of H₂O(s) at -14.0 degrees C to H₂O(g) at 141.0 degrees C?

A certain weak acid, HA, has a Ka value of 7.3

Explain how the induced, orientation, and dipersion interactions trend between HCl, HBr, and HI. Why do the dipersion interactions increase from HCl to HI? Why do the orientation interactions decrease from HCl to HI? Why are induced interactions greatest in HCl and lowest in HI?

Use the density and molecular weight of limonene, linalool, and nonane to calculate the volumes of the compounds you will need to make the stock solution of 50 mM. Also calculate the final concentration of those solutions after dilution.

Nonane: d = 0.718 g/mL, MW = 128.26, 99% pure

Limonene: d = 0.84 g/mL MW = 136.24, 96% pure

Linalool: d = 0.861 g/mL, MW = 154.25, 97% pure.

Preparing in 10mL volumetric flask.

1. Suppose 50.00 mL of 2.0 × 10–4 M Fe(NO3)3 is added to 50.00 mL of 2.0 ×10-6 M KIO3. Which of the following statements is true? For Fe(IO3)3, Ksp = 1.0 × 10–14.
A) A precipitate forms because Qc > Ksp.
B) A precipitate forms because Qc < Ksp.

C) No precipitate forms because Qc < Ksp.

D) No precipitate forms because Qc = Ksp.

E) No precipitate forms because Qc > Ksp.

2. For which of the following reactions is ∆S° > 0 at 25°C?

A) 2H2(g) + O2(g) → 2H2O(g)
B) 2ClBr(g) → Cl2(g) + Br2(g)
C) I2(g) → I2(s)

D) 2NO(g) + O2(g) → 2NO2(g)

E) NH4HS(s) → NH3(g) + H2S(g

3. What is E of the following cell reaction at 25°C? Cu(s) | Cu2+(0.017 M) || Ag(s), (Ag+ = 0.18M)

E°cell = 0.460 V.

A) 0.468V

B) 0.282 V

C) 0.460 V

D) 0.490 V

E) 0.479V

The recommended dose of quinine is 0.800 g/kg. If we assume the density is 1 g/ml what is the ph of this solution? the molar mass of quinine is 324.412. If 100 ml of this solution is titrated with a solution of 0.010 M HCL how many ml of HCL are required to reach the first equivalence point? what is the ph there? What is the PH when 32 ML of HCL have been added? what is the ph at the second equivalence point? what species of quinine is predominant at a ph of 2.5(in the stomach)? and 7.4 (in the blood)

Kb1= 1.0x10^-6

Kb2= 1.58x10^-10

The use of TLC to monitor the reaction of vanillin with enzymes produced by yeast relies on the fact that the reactant and product are expected to have very different R_f values. Could you use the same approach to monitor other reactions in which the reactant and product have very different R_f values? Explain this concept clearly, using diagrams to illustrate what you would expect to observe during a TLC analysis (as the reaction progresses toward completion) when the product is much less polar than the reactant.

1) Classify each of the following as a mixture, a compound, or an element?

table sugar, propane, bronze, tea, vinegar, dry ice, oxygen, aluminum

2) Select the statements that pertain to elements. Select all the statements that apply.
a) These can be broken down by physical means.
b) These cannot be broken down by chemical means.
c) These combine chemically to form new substances; they are building blocks of matter.
d) These are chemical combinations of simpler forms of matter.
e) These are pure substances.

3) Which of the following are chemical changes? Check all that apply.
a) sugar is dissolved in water
b) a warm coke bottle fizzes when opened
c) the copper roof turns green over time
d) baking soda is dissolved in vinegar and bubbles appear
e) a fog appears on your windshield in cold weather

4) Classify each property as physical or chemical.

a)susceptibility to rust

b) flammability

c) boiling point

d) melting point

e) conductivity

f) color

5) Which of these substances are elements? Check all that apply.

a) silicon

b) iodine

c) lead

d) quartz

e) silicone

f) water

1.

Consider the following generic reaction:

2A + B + C -> 2D +3E

From the following initial rate determinations, write the rate law for the reaction, determine the overall order for the reaction and calculate the rate constant, k.

Initial rate [A] [B] [C]

1.27x10^-4 Ms^-1 0.0125M 0.0125M 0.0125M

2.56x10^-4 Ms^-1 0.0250M   0.0125M 0.0125M

1.27x10^-4 Ms^-1 0.0125M   0.0250M 0.0125M

5.06x10^-4 Ms^-1 0.0125M 0.0125M 0.0250M

2. Consider the following reaction and its rate law:

2N2O5 -> 4NO2 + O2; rate = k[N2O5]

At 25 degrees Celsius, the half-life for this reaction is 96.3 minutes; calculate the initial N2O5 concentration, [N2O5]o, if [N2O5] = 1.80x10^-2 M after 60.0 minutes when the reaction proceeds at 25 degrees Celsius.