General Chemistry Answers

Calculate the molar concentration of each of the following:

a. 6.0 N sulfuric acid (in reactions that replace both hydrogens)

b. 3.5 N potassium hydroxide

c. 4.0 N phosphoric acid (in reactions that replace two hydrogen ions)

d. 6.2 N sodium hydroxide

1. Consider a buffer solution containing an acid with a pKa of 2.3 and an acid concentration that is one-fourth the concentration of the conjugate base. What is the pH of the solution?

2. Calculate the pH of a buffer containing 0.1 M sodium acetate and 0.2 M acetic acid (pKa= 4.76).

3. The pH of the given solution of lactic acid and lactate is 4.30. Calculate the pKa of lactic acid, when the concentration of lactic acid and lactate are 0.020 M and 0.073 M respectively.

1.Given the K values at 25°C, predict the extent of each reaction by indicating whether it is reactant-favored or product-favoured.

N2(g) + 3H2(g)2NH3(g)

K=3.5 ×10^8

CaCO3(s) Ca^+2(aq) + CO3 ^-2, (aq)

K= 3.8 x 10^-9

S(s) + 02(g) ----><------SO2(g)

K=4.2×10^52

AgCl(s) Ag^+1(aq) + Cl^-1(aq)

K=10^-10

Whatever the solvent used, the solution should be topped-up to its final volume using water. True or False?

The air-dried and sieved soil was placed into pots with a 25 cm diameter and a 27 cm height (8 kg per pot). Sulphur was used as the S source and the application rates were 0, 150, 300 mg kg−1 . The Se source was sodium selenite (Na2SeO3) and it was applied at 0 and 15 mg kg−1.

I will like to understand how they got the amount of selenite and sulphur added to the pot experiment?

An experimental data on the reaction of H₂ and PO₃^-3 is given below:

Experiment No. Initial [PO₃^-3] Initial [H₂] Initial Rate

1 0.100 0.100 1.50

2 0.200 0.100 3.00

3 0.100 0.200 6.00

a.  What is the order of reaction with respect to [PO₃^-3]?

b.  What is the order of reaction with respect to [H₂]?

c.  What is the overall reaction?

ESSAY.

Water, compared to other substances, has one of the highest specific heat values. What is the advantage of this fact for the human body?

Direction: Solve the following problems. Attach your solutions.

1. Calculate the standard enthalpy change ΔH°, for the following reaction:

2CH3OH (l) + 3O2 (g) --> 2CO2 (g) + 2H2O (g)

Given: CH3OH (l) -------> ΔHf° = -238.7 kJ

CO2 (g) -------> ΔHf° = -393.5 kJ

H2O (l) -------> ΔHf° = -285.8 kJ

1.Calculate the enthalpy change for the following chemical reaction:

SC2(l) + 3O@(g) --> CO2(g) + 2SO2(g)

1.C(s) + O2(g) --> CO2(g) ΔH° = - 393.5 kJ

2.S(s) + O2(g) --> SO2(g) ΔH° = - 296.8 kJ

3.C(s) + 2S(s) --> CS2(l) ΔH° = + 87.9 kJ

Calculate the heat released when 68.0 gram of steam at 124⁰C is converted to water

    at 45⁰C