Chemistry Answers

Find the weight of H2 stored in 100-cm3 cylindrical tank at 100

oC and 100 atm (10, 132.5 KPa)

using (a) Ideal gas equation (b) van der Waals equation if a = 0.244 atm-L

2

/mole

2 and b = 0.0266

L/mole. (Note: Use the method of successive approximation to solve for the mass of H2

)

Calculate the standard change in enthalpy for the given reaction:

2 Al(s) + Fe₂O₃(s) → Al₂O₃ (s) + 2 Fe(s)

Given:

ΔH° Fe₂O₃ (s) = -826 kJ/mol

ΔH° Al₂O₃ (s) = -1676 kJ/mol

 Calculate the standard heat of reaction for the following reaction. Express your answer in kcal/mol.

ΔH° CH₃ OH(l) = -57.0 kcal/mol

ΔH° CO₂ (g) = -94.1 kcal/mol

ΔH° H₂O(l) = -68.3 kcal/mol

2 CH₃OH(l) + 3 O₂(g) → 2 CO₂(g) + 4 H₂O(l)

a.      Calculate the pH of a solution consisting of 1.35M acetic acid (CH₃COOH)

 (pKa= 1.8 x 10^-5) and 2.83 M sodium acetate (NaC₂H₃O₂).

a.      Formic acid, which is a component of insect venom, has a Ka = 1.8 x 10^-4. What is the [H3O⁺] in a solution that is initially 0.20 M formic acid, HCOOH?  (4 pts.)

                HCOOH_(aq)  +  H₂O_(l)   ⇌   H₃O⁺_(aq)    +    HCOO^–_(aq)

(acid-base equilibria)

A research chemist adds a measured amount of HBr gas to pure water at 25^oC and obtains a solution with [H₃O⁺] = 8.3x10^-4 M. Calculate [OH^-]. Is the solution acidic, basic, or neutral? 

Describe what one would see at pressures and temperatures above 2.0 atm and 450 K.

95 ppm concentration is found in a solution with a total volume of 1500 mL, calculate the unknown volume of solute.

Refer to the First Law of Thermodynamics. Decide whether the statement below is TRUE or FALSE. Support your answer.

"Our energy supply is running out."

Write the expression for the equilibrium constant, for the following reaction: A (g) + 2B (aq) → 3C (s) + 4D (g)