a. A buffer solution contains 0.274 M NH₄Br and 0.379 M NH₃ (ammonia). Determine the pH change when 0.103 mol HBr is added to 1.00 L of the buffer.
pH after addition − pH before addition = pH change =

b. A buffer solution contains 0.432 M NaH₂PO₄ and 0.209 M K₂HPO₄. Determine the pH change when 0.113 mol KOH is added to 1.00 L of the buffer.
pH after addition − pH before addition = pH change =

1. By using the Clausius-Clapeyron equation, lnP=??HvapRT+C, derive the relationship between the vapor pressures, P1 and P2, and the absolute temperatures at which they were measured, T1 and T2.

Express your answer in terms of T1, T2, ?Hvap, and the gas constant R.

ln(P1/P2)=

2.

Gasoline is a mixture of hydrocarbons, a major component of which is octane, CH3CH2CH2CH2CH2CH2CH2CH3. Octane has a vapor pressure of 13.95 torr at 25?C and a vapor pressure of 144.78 torr at 75?C. Use these data and the equation in part (a) to calculate the heat of vaporization of octane.

Express your answer using two significant figures.

3.

By using the equation in part (a) and the data given in part (b), calculate the normal boiling point of octane.

Express your answer using three significant figures.

4.

Calculate the vapor pressure of octane at 29?C.

Express your answer using two significant figures.

Please show me how to solve for these. I have a 100 more and just need to see how one is done

PLEASE ANSWER ALL QUESTIONS

1. (1 pt) ______ Calculate the volume of 0.00500 M stock solution needed to make 10.00 mL of 0.00300 M solution.

             a. 16.7 mL

             b. 6.00 mL

             c. 0.0600 mL

             d. 3.00 mL

2. (2 pt) ______ If a solution sample has an extinction coefficient of 36.0 L mol^-1cm^-1, a pathlength of 1.00 cm, and an absorbance of 0.0900, what is the concentration of the solution in molarity? (Use Beer’s Law, A = εbc)

             a. 0.003 M

             b. 400 M

             c. 3.24 M

             d. 0.00250 M

3. (2 pt)   ______ What is the molar mass of Cu(C₂N₂H₈)₂SO₄? (Show the correct significant figures)

             a. 279.83  

             b. 183.76

             c. 219.72

             d. 278.  

4. (1 pt)   ______ What is λ_max?

             a. The extinction coefficient of a substance   

             b. The wavelength at which a substance absorbs the most light.

             c. The wavelength with the largest value.  

             d. The frequency of light that is maximum

Calculate the mass, in kg, of each sample.

1.91×10²⁶ cadmium atoms.

4.68×10²⁷ nickel atoms

2.11×10²⁷ manganese atoms.

2.73×10²⁹ lithium atoms.

Express your answer with the appropriate units.

Which of the following are redox reactions ? Explain your answer on the basis of changes in oxidation number.

1. CuSO₄ + 2NaOH → Cu(OH) ₂ + Na ₂SO₄

2. 2Al + 3MgSO₄ → 3Mg + Al ₂(SO₄)₃

3. 2(NH₄)₃PO₄ + 3Ba(NO₃)₂ → Ba ₃(PO₄)₂ + 6NH₄NO₃

4. 2HNO₃ + 3H₃AsO₃ → 2NO + 3H ₃AsO₄ + H₂O

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For the following reaction, 4.57 g of silver nitrate are mixed with excess copper. The reaction yields 2.29 gram of copper(II) nitrate What is the percent yield for this reaction?

Formula: % yield = (Actual yield/theoretical yield) x 100

2 AgNO₃(aq) + Cu(s) à Cu(NO₃)₂ (aq) + 2 Ag(s)

The melting point of a solid compound is reported as a range of two temperatures. For example, the literature (known) melting point of benzamide is 125-128 °C.

a.What does the first temperature in this range indicate?

b.What does the last temperature in this range indicate?

Q. A polydisperse sample of PS is prepared by mixing three monodisperse samples in the following proportions:

A : 1 g, 10,000 molecular weight PS

B : 2 g, 50,000 molecular weight PS

C : 2 g, 100,000 molecular weight PS

Using this information, calculate the number-average MW, weight-average MW and PDI of the mixture.

A detergent containing an unknown concentration of phosphate is analyzed using the standard addition method. Initially, this solution emitted an instrumental signal of 4.78 μA. An aliquot of 10.0 ml of 3.12 M phosphate solution was added to the 80.0 ml sample. After this addition, a signal of 9.77 μA was measured. Calculate the initial concentration of phosphate in the original sample of detergent.

a. A student weighs out 9.18 g of CrSO₄, transfers it to a 500. mL volumetric flask, adds enough water to dissolve the solid and then adds water to the 500 mL mark on the neck of the flask.
Calculate the concentration (in molarity units) of chromium(II) sulfate in the resulting solution? ______M

b. In the laboratory, a student adds 13.3 g of aluminum acetate to a 125 mL volumetric flask and adds water to the mark on the neck of the flask. Calculate the concentration (in mol/L) of aluminum acetate, the aluminum ion and the acetate ion in the solution.

c. Calculate the mass, in grams, of manganese(II) iodide that must be added to a 250-mL volumetric flask in order to prepare 250 mL of a 0.193 M aqueous solution of the salt. ____g

Order these chemical species by increasing pH of an 0.1M aqueous solution of each. That is, imagine making an 0.1M solution of each species. Select 1 next to the species that makes the solution with the lowest pH. Select 2 next to the species that makes the solution with the next higher pH, and so on. Notice that some of the rankings have been filled in for you already. Also notice that water is on the list. For that particular case, just compare the pH of pure water to the pH of the other solutions. Note for advanced students: for all charged species, you may assume the necessary counterions act as neither acids nor bases. species relative pH of 0.1M aqueous solution H2C2O4 ▼1 (lowest) H3O+ ▼(Choose one) H3PO4 4 HIO3 2 IO3− ▼(Choose one) HC2O4− 7 H2O 5 H2PO4− ▼(Choose one)

BrO3- (aq) + 5Br- (aq) + 6H+ (aq)  → 3Br2 (l) + 3H2O (l)

1. what is the rate law?

2. what is the rate constant?

3. what is the overall order?

How many joules will be required to convert 354.0 grams of benzene to vapor at 25 °C? (ΔH vap of benzene is 33.9 kJ.)

Calculate the number of molecules present in each of the following samples.

4.75mmol of phosphine,

4.75g of phosphine,

1.25x10-2g of lead(II) acetate, ‍ ‍

1025x10-2 moles of lead(II) acetate, ‍ ‍

a sample of benzene, ‍ , C6H6 which contains a total of 5.40

moles of carbon

56.7 mL of 1.18 M hydrochloric acid is added to 28.7 mL of barium hydroxide, and the resulting solution is found to be acidic.
21.3 mL of 1.27 M sodium hydroxide is required to reach neutrality.
what is the molarity of the original calcium hydroxide solution? __M

52.0 mL of 0.757 M hydrochloric acid is added to 12.1 mL of potassium hydroxide, and the resulting solution is found to be acidic.
20.8 mL of 0.630 M calcium hydroxide is required to reach neutrality.
what is the molarity of the original potassium hydroxide solution. __M