Answer:
0.295 mol/L
Explanation:
Given data:
Volume of solution = 3.25 L
Mass of BaBr₂ = 285 g
Molarity of solution = ?
Solution:
Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.
Formula:
Molarity = number of moles of solute / L of solution
Number of moles of solute:
Number of moles = mass/ molar mass
Molar mass of BaBr₂ = 297.1 g/mol
Number of moles = 285 g/ 297.1 g/mol
Number of moles= 0.959 mol
Molarity:
M = 0.959 mol / 3.25 L
M = 0.295 mol/L
The empirical formula is obtained by calculating the mole ratios of the atoms in the elements.
The number of moles =mass/ R.A.M
For hydrogen, no. of moles=8/1=8
For oxygen, no. Of moles=64/16=4
The tabular solution is attached.
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1) Chemical reaction: HCN + H₂O → CN⁻ + H₃O⁺.
c(HCN) = 2,2 M = 2,2 mol/L.
pKa(HCN) = 9,21.
Ka = 6,16·10⁻¹⁰.
[CN⁻] = [H₃O⁺] = x.
[HCN<span>] = 2,2 M - x.
</span>Ka = [CN⁻] · [H₃O⁺] / [HCN].
6,16·10⁻¹⁰ = x² / 2,2 M -x.
Solve quadratic equation: [CN⁻] = [H₃O⁺] = 0,0000346 M.
[HCN] = 2,2 M - 0,0000346 M = 2,199 M.
2) pH = - log[H₃O⁺].
pH = -log( 0,0000346 M).
pH = 4,46.
Hydrocyanic acid and hydronium ion (H₃O⁺) are acids. Cyanide anion (CN⁻) is the strongest base in the system, cyanide anion accept protons in chemical reaction.
pKb = pKw - pKa.
pKb = 14 - 9,21 = 4,79.
