When a pink aqueous solution of potassium permanganate, faintly acidified with dilute sulfuric acid was treated with 10% aq. hydrogen peroxide, the reaction took place with the evolution of gas bubbles, and the pink solution was turned colorless. Further chemical analysis revealed that the evolved gas was oxygen, and the resulting solution contains potassium sulfate and manganese (II) sulfate; water was also formed during the same reaction. Please answer the followings: 1) Write down the proper chemical equation for this reaction. 2) Balance the chemical equation. 3) Define the type/types of the reaction, and offer an explanation for the color change. 4) Write down the ions (and define types) present in the solution before & after the reaction. 5) If initially 5.65 g of potassium permanganate was taken for the reaction, calculate the total number of moles of manganese (II) sulfate present in the solution after the completion of the reaction

What is the equivalence point pH for the titration of 25ml 0.80M diethyleneamine (kb = 5.9x10-4) titrated by 0.60M strong acid? A. 3.74 B. 5.62 C.6.55 D. 8.62

Complete the following table:

Ppm                 Grams                         Air Volume (l)            Mol. Wt. (g)

_______        0.02542                           75                               339

2                    0.00228                          300 _____

1000                7.164 _____ 146

0.002 _____ 2650 254

Complete and balance the following equations, and identify the oxidizing and reducing agents. (Use the lowest possible coefficients. Include states-of-matter (s), (l), (g), (aq) similar to the given reaction.)

a.)  MnO₄^-(aq) + CH₃OH(aq) ? Mn²⁺(aq) + HCO₂H(aq) (acidic solution)

b.) H₂O₂(aq) + Cl₂O₇(aq) ? ClO₂^-(aq) + O₂(g) (basic solution)

c.) Cr₂O₇^2-(aq) + I^-(aq) ? Cr³⁺(aq) + IO₃^-(aq) (acidic solution)

d.)  As(s) + ClO₃^-(aq) ? H₃AsO₃(aq) + HClO(aq) (acidic solution)

A buffer solution is composed of 1.905 g of KH2PO4 and 5.181 g of Na2HPO4. ( Ka for dihydrogen phosphate ion is 6.2x10^-8 .)

a. What is the pH of the buffer solution?

pH =  

b. What mass of KH2PO4 must be added to decrease the buffer solution pH by 0.10 unit from the value calculated in part a?

Mass =

(Volume not given)

8.03 x 10^23 moleucles of oxygen react with excess nitrogen. what is the maximum number of grams of dinitrogen tetroxide that can be produced?

42 grams of cyclohexane burns in excess air to form carbon dioxide and water. How many grams of carbon dioxide and of water vapor are produced?

Suppose a particular mechanism has the following equilibria:

Ni(CO)_4(g) ⇌ Ni_(s) + 4 CO_(g)               K₁ = 8.77             ΔH₁ = 190 kJ

MnO_(s) + CO_(g) ⇌ Mn_(s) + CO_2(g)        K₂ = 490              ΔH₂ = 349 kJ

Mn_(s) + H₂O_(g) ⇌ MnO_(s) + H_2(g)         K₃ = 0.0149          ΔH₃ = -346 kJ

Determine the values of the equilibrium constant and enthalpy change for the net equation:

Ni(CO)_4(g) + 4 H₂O_(g) ⇌ Ni_(s) + 4 CO_2(g) + 4H_2(g)        K_c = ?     ΔH = ?

(You’ll want to review the rules for manipulating the stoichiometry of an equilibrium reaction and its equilibrium constant in section 14.3 of the textbook. It is different than using Hess’s Law to find the net enthalpy change.)

3 species do not appear in the net question. Which are they? Classify each as an intermediate or a catalyst. How do you know the difference?

I need to write a lab plan based on preparing a standard solution-- Standardization of NaOH (aq)

Experiment 8: Preparing a Standard Solution—Standardization of NaOH(aq) Learning Objectives » to understand the meaning of the term primary standard » to learn how to determine the precise concentration of a solution » to learn how to properly prepare, use and read a buret » to practice titration techniques and calculations » to learn how to weighing by difference Read and complete the Prelab Assignment for Experiment 8 (Chemistry 121 Lab Moodle site). Note that these assignments are always due the Sunday the week of lab, by 5 PM. Safety: 3.0 M sodium hydroxide is hazardous and will attack skin and clothing rapidly. Don't wear expensive clothes to lab. Flood any spills with water and ask your instructor or assistant for help. Wear goggles! If solutions are splashed on your face, call for help and use the eyewash. Materials 3 M NaOH, solid KHP (potassium hydrogen phthalate) dried, in weighing bottles, phenolphthalein indicator solution, one buret, four 250-mL Erlenmeyer flasks. Disposal The solutions of KHP and dilute NaOH should be neutralized (5 < pH < 9) and only then may be poured down the drain with lots of water. This is a skill-building experiment, where you will have to work carefully and use equipment skillfully in order to achieve good results. Learning good titration techniques will be helpful in subsequent labs, not only as specific skills, but they illustrate the excellent results that can be achieved if sound technique is employed. Students can work individually or in pairs on this experiment. Remember, it's up to you to make sure that you take part in all lab activities!

A beaker with 1.10×10^2 mL of an acetic acid buffer with a pH of 5.000 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100 mol L−1. A student adds 7.00 mL of a 0.490 mol L−1 HCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.760.

Please show where all numbers comes from.

10) Aluminum doesn’t readily corrode because:

a) its standard reduction potential is more positive than oxygen

b) its standard reduction potential is more negative than oxygen

c) it forms a dense coating of alumina, Al₂O₃, that slows oxidation.

d) It is already oxidized.

.

11) What best describes a glass?

a) A transparent, crystalline insulator.

b) A viscous liquid

c) An amorphous solid

d) The thermodynamic (lowest energy) state for a material

.

For the following reaction answer questions 13 & 14):

                       Fe(s) + Cu²⁺(aq)            Fe²⁺(aq) + Cu(s)

13) What is being oxidized (oxidant)?

a) Fe²⁺

b) Cu²⁺

c) Cu

d) Fe

.

14) What is being reduced (reductant)?

a) Fe²⁺

b) Cu²⁺

c) Cu

d) Fe

Please answer all of them without guessing!!! Thanks

Use the following thermodynamic data to calculate ∆S° (universe) for the formation of HBr(g) from its elements at 298K in J/K.   HINT: write the formation reaction for HBr(g)

Species        ∆H_f° (kJ/mol)        S° (J/Kmol)                  Species      ∆H_f° (kJ/mol)      S° (J/Kmol)

HBr(g)           -36.3                   198.59                               Br₂(g)          30.91                245.38

Br₂(l)                  0                   152.23                              H₂(g)              0                     130.6

Arrange the following 0.10 M

solutions in order of increasing acidity: (i) NH4NO3, (ii) NaNO3, (iii) CH3COONH4, (iv) NaF, (v) CH3COONa.

There are several classifications of chemical reactions. Please research a reaction and provide its particular classification and characterization(s).

Balance the following aqueous reactions:

a. CrI₃ + Cl₂ -----> CrO₄^2- + IO₄^1- + Cl^1- (basic solution)

b. Cr(NCS)₆^4- + Ce⁴⁺ ----> Cr³⁺ + Ce³⁺ + NO₃^1- + CO₂ + SO₄^2- (acidic solution)