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.
A centimeter(cm) is larger than a millimeter(mm).The tiny dashes are millimeters and there are ten millimeters in a centimeter so, the tiny dashes are millimeters that count as 1 and the slightly longer one is half of a centimeter meaning 5.
Does it make sense? :)
Answer:
All three are present
Explanation:
Addition of 6 M HCl would form precipitates of all the three cations, since the chlorides of these cations are insoluble: .
- Firstly, the solid produced is partially soluble in hot water. Remember that out of all the three solids, lead(II) choride is the most soluble. It would easily completely dissolve in hot water. This is how we separate it from the remaining precipitate. Therefore, we know that we have lead(II) cations present, as the two remaining chlorides are insoluble even at high temperatures.
- Secondly, addition of liquid ammonia would form a precipitate with silver: ; Silver hydroxide at higher temperatures decomposes into black silver oxide: .
- Thirdly, we also know we have in the mixture, since addition of potassium chromate produces a yellow precipitate: . The latter precipitate is yellow.
Answer:
The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds. When discussing the octet rule, we do not consider d or f electrons.
Explanation:
Metamorphic I think somebody verify it’s been a while