Solution:
We have to use the Henderson-Hasselbalch equation: for this calculation
Henderson–Hasselbalch equation describes the derivation of pH as a measure of acidity by using pKa, the negative log of the acid dissociation constant in biological and chemical systems. The equation is also useful for estimating the pH of a buffer solution and finding the equilibrium pH in acid-base reaction.
The equation is given by:
Here, [HA] is the molar concentration of the un dissociated weak acid, [A⁻] is the molar concentration (molarity, M) of this acid's conjugate base and pKa is −log10 Ka where Ka is the acid dissociation constant, that is:
pH = pKa + log([A^-]/[HA])
We look up the pKa for acetic acid:
pKa = 4.76
Let x = molarity of AcO^- and y = molarity of AcOH: Then we have the following two equations in two unknowns:
(1) x + y = 0.10 M
and
(2) 4.9 = 4.76 + log(x/y)
Further calcite the value of x and y by algebraic method and get the answer.
Answer:
(a) Three translational degrees of freedom, 2 rotational degrees. 5 total
Cv = 5/2 R; Cp = 7/2 R
(b) and (c) 6 total degrees of freedom ( 3 translational, 3 rotational)
Cv = 3 R ; Cp = 4R
Explanation:
(a) O₂
Oxygen being a diatomic molecule has three translational degrees of freedom and two rotational degrees of freedom since it can move in the three axis and can rotate around two.
(b) H₂O
This is a polyatomic molecule and it has three translational and three rotational degrees of freedom.
(c) Same as water it has three translational degrees of freedom and three rotational degrees of freedom
To calculate the heat capacities we have to make use of the equipartition theorem which tell us that for each degree of freedom imparts 1/2 R to the heat capacity at constant volume.
(a)
5 total degrees of freedom ⇒ Cv = 5/2 R
Cp ( heat capacity at constant pressure) is determined from the relation
Cp - Cv = R
Cp = 7/2 R for O2 molecule
(b) and (c)
Total degrees of freedom 6
Cv = 3 R
Cp = 4 R
Here we are ignoring any contribution of the vibrational modes to the contribution of the heat capacities
Firstly calculating number of moles of hcl disssolved. The answer would be in the pic above. Concentration of hydrogen ions can be calculated by using that mole amount dividing by 3litres of solution to get 0.003196. Hence the ph of solution will be -log10(h+ concentration) which is equal to 2.495
