Find the pH of a solution containing 0.025 M chloric acid and 0.35 M hypochlorous acid.
1 answer:
Answer:
1.91
Explanation:
The chlorous acid is 340 000 times stronger than the hypochlorous acid. It will suppress the ionization of HOCl to such an extent that we can ignore the HOCl in our calculations.
The equation for the equilibrium of HClO₂ is
HClO₂ + H₂O ⇌ H₃O⁺ + ClO₂⁻; Kₐ= 1.2 × 10⁻²
For ease of typing, let’s rewrite the equation as
HA + H₂O ⇌ H₃O⁺ + A⁻
Set up an ICE table:
HA + H₂O ⇌ H₃O⁺ + A⁻
I: 0.025 0 0
C: -x +x +x
E: 0.025-x x x
Set up the Kₐ expression
Kₐ = {[H₃O⁺][A⁻]}/[HA] = 1.2 × 10⁻² Substitute values
(x × x)/(0.0250-x) = 1.2 × 10⁻² Combine like terms
x²/(0.025-x) = 1.2 × 10⁻²
Check that x ≪ 0.025
0.025/(1.2 × 10⁻²) = 2.1
The ratio is less than 400. We must solve a <em>quadratic equation </em>
Set up the quadratic equation.
x²/(0.025-x) = 1.2 × 10⁻²
x² = (0.025 - x)(1.2 × 10⁻²)
x² = 3.00 × 10⁻⁴ - 1.2 × 10⁻²x
x² + 1.2×10⁻²x – 3.00×10⁻⁴ = 0
Solve the quadratic equation
The solutions to the quadratic equation are
a = 1
b = 1.1 × 10⁻²
c = -1.65 × 10⁻³
Substituting the values into the equation, we get
x = 0.0123 and x = -0.02435
b =We reject the negative value, so
x = [H₃O⁺] = 0.0123 mol·L⁻¹
Calculate the pH
pH = -log[H₃O⁺]
pH = -log(0.0123)
pH = 1.91
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Answer:
Option C, (Actual yield ÷ percent yield) × 100
Explanation:
Theoretical yield is defined as the total amount of product formed for given reactants in a chemical reaction. It is an ideal case which assumes no exceptions or wastage.
The mathematical relation between the actual yield, percent yield and theoretical yield is as follows -
Where
P.Y. represents the percent yield a
M A.Y. represents the mass obtained from actual yield
M T.Y. represents the mass obtained from theoretical yield
Hence, if we rearrange the formula, we get -
Hence, option C is correct