If you start with 0.30 m Mn₂ , at 12.5 pH, free Mn₂ concentration be equal to 4.6 x 10⁻¹¹ m
Initial molarity of Mn₂ = 0.30 M
Final molarity of Mn₂ = 4.6 x 10⁻¹¹
pH = ?
Ksp [Mn(OH)₂] = 4.6 x 10⁻¹⁴ (standard value)
Write the ionic equation
Mn(OH)₂ → Mn⁺² + 2OH⁻
[Mn⁺²] = 4.6 x 10⁻¹¹
We will calculate the concentration of OH⁻ by using Ksp expression
Ksp = [Mn⁺²][OH-]²
[Mn⁺²][OH⁻]² = 4.6 x 10⁻¹⁴
[OH⁻]² = 4.6 x 10⁻¹⁴ / 4.6 x 10⁻¹¹
[OH⁻]² = 10⁻³
[OH⁻] = (10⁻³)¹⁽²
[OH⁻] = 0.0316 M
Calculate the pOH
pOH = -log [OH⁻]
pOH = -log [0.0316]
pOH = 1.5
Now calculate pH
pH = 14 - pOH
pH = 14 - 1.5
pH = 12.5
You can also learn about molarity from the following question:
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It makes an ecosystem stable
The mass of NiCl₂•6HO₂ needed to prepare a 0.035 M 500 mL solution of NiCl₂•6HO₂ is 4.165 g
<h3>What is molarity? </h3>
This is defined as the mole of solute per unit litre of solution. Mathematically, it can be expressed as:
Molarity = mole / Volume
<h3>How to determine the mole of NiCl₂•6HO₂</h3>
- Molarity = 0.035 M
- Volume = 500 mL = 500 / 1000 = 0.5 L
Mole = Molarity × Volume
Mole of NiCl₂•6HO₂ = 0.035 × 0.5
Mole of NiCl₂•6HO₂ = 0.0175 mole
<h3>How to determine the mass of NiCl₂•6HO₂</h3>
- Mole of NiCl₂•6HO₂ = 0.0175 mole
- Molar mass of NiCl₂•6HO₂ = 238 g/mol
Mass = mole × molar mass
Mass of NiCl₂•6HO₂ = 0.0175 × 238
Mass of NiCl₂•6HO₂ = 4.165 g
Thus, 4.165 g of NiCl₂•6HO₂ is needed to prepare the solution
Learn more about molarity:
brainly.com/question/15370276
A requires oxygen
The reason is that fermentation does not always need oxygen.
