ASAP
2 answers:
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Mass of the water : 2.23 g
<h3>Furter explanation</h3>Heat
Q = m.c.Δt
m= mass, g
c = heat capacity, for water : 4.18 J/g° C.
ΔT = temperature
Q= 140 J
Δt = 75 - 60 = 15
mass of the water :
Answer:
- pKa = 7.46
Explanation:
<u>1) Data:</u>
a) Hypochlorous acid = HClO
b) [HClO} = 0.015
c) pH = 4.64
d) pKa = ?
<u>2) Strategy:</u>
With the pH calculate [H₃O⁺], then use the equilibrium equation to calculate the equilibrium constant, Ka, and finally calculate pKa from the definition.
<u>3) Solution:</u>
a) pH
- pH = - log [H₃O⁺]
- 4.64 = - log [H₃O⁺]
b) Equilibrium equation: HClO (aq) ⇄ ClO⁻ (aq) + H₃O⁺ (aq)
c) Equilibrium constant: Ka = [ClO⁻] [H₃O⁺] / [HClO]
d) From the stoichiometry: [CLO⁻] = [H₃O⁺] = 2.29 × 10 ⁻⁵ M
e) By substitution: Ka = (2.29 × 10 ⁻⁵ M)² / 0.015M = 3.50 × 10⁻⁸ M
f) By definition: pKa = - log Ka = - log (3.50 × 10 ⁻⁸) = 7.46
<u>Answer:</u> The Van't Hoff factor for KCl is 1.74
<u>Explanation:</u>
We are given:
Molality of solution = 1 m
This means that 1 mole of a solute is present in 1 kg of solvent (water) or 1000 grams of water
To calculate the number of moles, we use the equation:
Given mass of water = 1000 g
Molar mass of water = 18 g/mol
Putting values in above equation, we get:
Mole fraction of a substance is given by:
Moles of solute = 1 moles
Total moles = [1 + 55.56] = 56.56 moles
Putting values in above equation, we get:
The equation used to calculate relative lowering of vapor pressure follows:
where,
= relative lowering in vapor pressure = 0.734 mmHg
i = Van't Hoff factor = ?
= mole fraction of solute = 0.0177
= vapor pressure of pure water = 23.76 torr
Putting values in above equation, we get:
Hence, the Van't Hoff factor for KCl is 1.74