Answer:
Volume required = 0.327 L
Explanation:
Given data:
Volume in L = ?
Molarity of solution = 1.772 M
Mass of BaCl₂ = 123 g
Solution:
First of all we will calculate the number of moles of BaCl₂,
Number of moles = mass/molar mass
Number of moles = 123 g/ 208.23 g/mol
Number of moles = 0.58 mol
Now, given problem will solve by using molarity formula.
Molarity = number of moles / volume in L
1.772 M = 0.58 mol / Volume in L
Volume in L = 0.58 mol / 1.772 M
Volume in L = 0.327 L
Answer:
pH = 4.25
Explanation:
A solution composed of a weak acid and its conjugate base is a <em>buffer solution</em>. To calculate the pH of a buffer solution we use the Henderson-Hasselbach equation:
pH = pKa + log ([conjugate base]/[weak acid]
In this case, we have the following data:
[conjugate base] = [sodium benzoate] = 0.230 M
[weak acid] = [benzoic acid] = 0.205 M
The pKa of benzoic acid is 4.2. So, we introduce the data in the equation:
pH = 4.2 + log (0.230 M/0.205 M) = 4.2 + 0.050 = 4.25
Balanced chemical reaction (dissociation) : CaCl₂(aq) → Ca²⁺(aq) + 2Cl⁻(aq).
n(CaCl₂) = 3,5 mol.
From chemical reaction: n(CaCl₂) : n(Ca²⁺) = 1 : 1.
n(Ca²⁺) = 3,5 mol.
From chemical reaction: n(CaCl₂) : n(Cl⁻) = 1 : 2.
n(Cl⁻) = 2 · 3,5 mol.
n(Cl⁻) = 7 mol.
Calcium chloride is salt that completely dissociate in water on calcium cations and chlorine anions.
Because if you change two things then you do not know which one has affected or altered the dependent variable. if you only change one then you know what exactly changed and why
