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.
C :)
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<span>Answer is 6.66 mol.
<em>Explanation:</em>
According to the
Avogadro's constant, 1 mole of substance has 6.022 × 10²³ particles.
Number of Zinc atoms = </span>4.01 x 10²⁴
Avogadro's constant = 6.022 × 10²³ mol⁻¹
Hence,
moles of Zinc = number of Zinc atoms / Avogadro's constant
= 4.01 x 10²⁴ / 6.022 × 10²³ mol⁻¹
= 6.66 mol
The answer is that; the outermost shell of all atoms with two or more electron shells will not have more than 8 electrons.
Elements in the same group in the periodic table have similar chemical properties. This is because their atoms have the same number of electrons in the outermost energy level. On the other hand elements in the same period have the same number of energy levels and differ in chemical properties since they belong to different groups.
The question is incomplete. But this is a typical thermodynamic problem. Looking at the given data and knowing that it is an isothermal process, the most probable question would be, the final pressure of the system. The solution is as follows:
For state 1,
PV=nRT
P₁(100 L)(1 m³/1,000 L) = (5 mol)(8.314 m³Pa/molK)(300 K)
P₁ = 124,710 Pa
For isothermal process:
P₁V₁ = P₂V₂
(124,710 Pa)(100 L)= P₂(500 L)
Solving for P₂,
<em>P₂ = 24,942 Pa</em>
