Answer:
A) pH of Buffer solution = 4.59
B) pH after 5.0 ml of 2.0 M NaOH have been added to 400 ml of the original buffer solution = 4.65
Explanation:
This is the Henderson-Hasselbalch Equation:
![pH = pKa + log\frac{[conjugate base]}{[acid]}](https://tex.z-dn.net/?f=pH%20%3D%20pKa%20%2B%20log%5Cfrac%7B%5Bconjugate%20base%5D%7D%7B%5Bacid%5D%7D)
to calculate the pH of the following Buffer solutions.
Data: molar mass 470 g/mol
Percent composition:
Hg = 85.0%
Cl = 15.0%
Solution:
1) Convert % to molar ratios
A. Base: 100 g
=> Hg = 85.0 g / 200.59 g/mol = 0.4235 mol
Cl = 15.0 g / 35.45 g/mol = 0.4231 mol
B. divide by the higher number and round to whole number
Hg = 0.4325 / 0.4231 = 1.00
Cl = 0.4231 / 0.4231 = 1.00
=> Empirical formula = Hg Cl
2) Find the mass of the empirical formula:
HgCl: 200.59 g/mol + 35.45 g/mol = 236.04
3) Determine how many times is the empirical mass contained in the molecular mass:
470 g/mol / 236.04 = 1.99 ≈ 2
=> Molecular formula = Hg2 Cl2.
Answers:
Empirical formula HgCl
Molecular Formula Hg2Cl2
1. Q=112.8 kJ
2. Q=5.01 kJ
<h3>Further explanation</h3>
The heat required for phase change :
Q = mLf
Lf=latent heat of fusion
- vaporization/condensation
Q = mLv
Lv=latent heat of vaporization
1.
m=50 g=0.05 kg
Lv (water) = 2256 kJ/kg
2.
m=15 g=0.015 kg
Lf for water = 334 kj/kg
This is a redox reaction.
3Fe + 2O₂ → Fe₃O₄ (Fe⁺²O·Fe⁺³₂O₃)
Fe - 2e⁻ = Fe⁺²
Fe - 3e⁻ = Fe⁺³
O₂ + 4e⁻ = 2O⁻²
