General Chemistry Answers

What is the pH of the solution containing 0.20 M NH3 and 0.15 M NH4Cl?

Cite 2 instances that will make a buffer effective.

Write 50 word describing Henderson-Hasselbalch in chemistry.

What is the entropy change of the reaction below at 298 K and 1 atm 

pressure?

 N2(g) + 3H2(g) → 2NH3(g)

S

298 (J/mol•K) 191.5 130.6 192.3 

(a) –198.7 J/K (c) –129.7 J/K

(b) 76.32 J/K (d) 303.2 J/K

2. Evaluate ΔSo for the reaction below at 25°C and 1 atm.

3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g)

So (J/mol•K) 240 69.91 146 210.7

(a) +1.37 x 103 J/K (c) –287.2 J/K

(b) +287.2 J/K (d) +1.37 x 103 J/K

3. The heat of vaporization of methanol, CH3OH, is 35.20 kJ/mol. Its boiling 

point is 64.6°C. What is the change in entropy for the vaporization of 

methanol?

(a) –17.0 J/mol•K (c) 17.0 J/mol•K

(b) 3.25 J/mol•K (d) 104 J/mol•K

what is the boiling point of a solution prepared

A student plotted a titration curve after titrating nitrous acid (HNO2) with potassium hydroxide

(KOH). The student started by placing 45.0 ml of 0.150 M HNO2 in a beaker and titrated to the endpoint and beyond with 0.120 M KOH.

Ka for HNO2 = 4.5 x 10-4

a) Draw a sketch of the titration curve with labels on the following: 1) endpoint volume (show the value)

2) approximate endpoint pH (relative to 7)

3) half-equivalence point (show the value)

 b) Write the chemical equation for the dissociation of nitrous acid and then the equilibrium constant expression (Ka).

c) Determine the pH of the solution at the half equivalence point.

d) Determine the pH of the solution at the endpoint of the titration.

1.  What is the final volume when you have a pressure increase of 2.3 atm to 1245  mm Hg?

Give the structure for diamminesilver(1)dicyanidoargentate(1)

Q2): It is required to heat 10000 bbl/ day of crude oil (as given in case study of Lecture3) in a fired still heater from 220 °F to 622 °F and vaporize (gasoline, naphtha, kerosene, light gasoil, heavy gasoil) of the crude oil using refining gas, (NHV-50000 Btu/lb). In the radiant section contains 1500 ft of projected area, and the tubes (5 in. outside diameter) are spaced at a center to-center distance of 10 in. there is only one row of radiant tubes, and they are 40 ft long. The ratio of air to fuel is 17.

Given: Average Specific heat of the crude oil = 2.3 Btu/ lb °F, average latent heat of vaporization is 120, 113, 100, 95, 90 Btu/lb for (gasoline, naphtha, kerosene, light gasoil, heavy gasoil) respectively. and the furnace efficiency is 75% calculate:

a) The mass flow rate of the fuel required?

b) How many Btu are absorbed per hour in radiant section?

c) How many Btu are absorbed per hour through each square foot of projected area?

Given:

1 bbl=42 gal.

P water -8.33 Lb/gal

What is the volume of oxygen liberated at the anode at the same time as 0.32g of copper is deposited on the cathode when cuso4 solution is electrolysed between platinum electrode, given that relative atomic mass = 64 and s.t.p. of any gas = 22.4 dm³