The reaction N2O(g) + O2(g) NO2(g) +NO(g) has ΔHº = -42.9 kJ and ΔSº = -26.1 J/K. Suppose 0.400 mol of N2O and 0.400 of O2 are placed in a 8.00 L container at 400 ºC and this equilibrium is established. What percentage of the N2O has reacted? (Note: Assume that ΔH and ΔS are relatively insensitive to temperature, so ΔHº298 and ΔSº298 are about the same as ΔHº673 and ΔSº673 respectively.) Enter your answer with 2 significant digits.

The decomposition of N2O to N2 and O2 is a first-order reaction. At 730° C the half-life of the reaction is 3.58 × 103 min. If the initial pressure of N2O is 5.50 atm at 730° C, calculate the total gas pressure after one half-life. Assume that the volume remains constant.

_____atm

A rock is 4.2% by mass fayalite (Fe2SiO4), 8.4% by mass forsterite (Mg2SiO4), and the remainder silicon dioxide. What is the mass percent of each element in the rock?

_% Fe

_% Mg
_% Si

_% O

A 30.00 mL sample of 0.0100M MgEDTA^2- solution was added to a 30.00 mL sample containing Fe³⁺. The solution was then buffered to pH 10 and titrated with 12.83 mL of 0.0152 M EDTA to an Eriochrome Black-T endpoint. What was the [Fe³⁺] in the original sample?

Please show work.

A student obtained the following data for the gas phase decomposition of nitrosyl chloride at 400 K. NOCl(g)NO(g) + ½ Cl2(g) [NOCl], M 8.40×10-2 4.20×10-2 2.10×10-2 1.05×10-2 seconds 0 2.78×104 8.33×104 1.94×105 (1) What is the half-life for the reaction starting at t=0 s? s What is the half-life for the reaction starting at t=2.78×104 s? s Does the half-life increase, decrease or remain constant as the reaction proceeds? (2) Is the reaction zero, first, or second order? (3) Based on these data, what is the rate constant for the reaction? M-1s-1

Given: A 70.0 mL solution of 0.191 M ammonia is titrated with 0.191 M HCl. The pKa for ammonium is 9.3.

Question:

The titration is basically figuring out what is in the breaker and selecting the correct formula.

1) 0.0mL HCl Added

What is in the beaker: __________

What is the formula ? __________

Calculate the numbers:

Find the pH. :

2) 25 mL of HCl Added

• What is in the beaker? _____________

• What is the formula: ____________

The numbers come from stoichiometry of the titration reaction.

Put the numbers in:

pH = ?

What volume of 0.115 M HClO4 solution is needed to neutralize 41.00mL of 9.00

Calculate the percent ionization of formic acid solutions having the following concentrations.

a) 1.20M

b)0.450M

c)0.130M

d)5.10 x 10^-2

State if each of the following salts is acidic, basic, or neutral. Briefly, give your reason for each choice.

BaI₂, LiBr, NH₄Br, CH₃NH₃CN, and Ca₃(PO₄)₂

Is there some kind of trick or way to find the answer?

A beaker with 2.00×10² 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 M. A student adds 4.40 mL of a 0.390 M HCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.740.

Express your answer numerically to two decimal places. Use a minus ( − ) sign if the pH has decreased.

HA 25

PART B: The following reaction was performed in a sealed vessel at 712 ∘C: H2(g)+I2(g)⇌2HI(g)

Initially, only H2 and I2 were present at concentrations of [H2]=3.55M and [I2]=2.30M . The equilibrium concentration of I2 is 0.0300 M . What is the equilibrium constant, Kc, for the reaction at this temperature?

Express your answer numerically.

A sample of a chromium-containing alloy weighing 3.450 g was dissolved in acid, and all the chromium in the sample was oxidized to 2CrO42–. It was then found that 3.18 g of Na2SO3 was required to reduce the 2CrO42– to CrO2– in a basic solution, with the SO32– being oxidized to SO42–. Write a balanced equation for the reaction of 2CrO42– with SO32- in a basic solution. How many grams of chromium were in the alloy sample? What was the percentage by mass of chromium in the alloy? Review Problem 5.097a Incorrect. Did you have the chromium being reduced? Did you balance out the electrons properly so none remained in the final balanced equation? Enter a balanced net ionic equation for the reaction between 2CrO42- and SO32- in a basic solution.

For Tc-98, Tc-97, and Tc-96 what are the following for each?

1. A 33.6 mL sample of a 0.494 M aqueous acetic acid solution is titrated with a 0.379 M aqueous sodium hydroxide solution. What is the pH after 14.8 mL of base have been added?

pH =

2.How many grams of solid ammonium bromide should be added to 0.500 L of a 0.234 M ammonia solution to prepare a buffer with a pH of 10.120 ?

grams ammonium bromide =

3. How many grams of solid sodium nitrite should be added to 2.00 L of a 0.151 M nitrous acid solution to prepare a buffer with a pH of 2.593 ?