Answer:
46.40 g.
Explanation:
- It is a stichiometric problem.
- The balanced equation of the reaction: 4K + O₂ → 2K₂O.
- It is clear that 4.0 moles of K reacts with 1.0 mole of oxygen produces 2.0 moles of K₂O.
- We should convert the mass of K (38.5 g) into moles using the relation:
<em>n = mass / molar mass,</em>
n = (38.5 g) / (39.098 g/mol) = 0.985 mole.
<em>Using cross multiplication:</em>
4.0 moles of K produces → 2.0 moles of K₂O, from the stichiometry.
0.985 mole of K produces → ??? moles of K₂O.
∴ The number of moles of K₂O produced = (0.985 mole) (2.0 mole) / (4.0 mole) = 0.4925 mole ≅ 0.5 mole.
- Now, we can get the mass of K₂O:
∴ mass = n x molar mass = (0.5 mole) (94.2 g/mol) = 46.40 g.
Answer:
Ha is more acidic than Hb because loss of Ha forms a resonance-stabilized conjugate base.
Explanation:
The carbon atom that is next to the carbonyl group in pentan-2-one is known as the alpha carbon atom, this carbon atom bears the Ha, the alpha hydrogen atoms.
Ha is more acidic than Hb because, loss of Ha leads to the formation of a resonance stabilized enolate ion. This resonance stabilization of the ion formed makes loss of Ha an easier process than loss of Hb, hence the answer above.
Answer:
pH = 11.05
Explanation:
It is possible to answer this question using Henderson-Hasselbalch formula:
pH = pka + log₁₀ [A] / [HA⁺]
Where A in this case is weak base (dimethylamine) and conjugate acid (HA⁺) is dimethylamine hydrochloride.
As Ka= Kw / Kb = 1x10⁻¹⁴ / 7.4x10⁻⁴ = 1.35x10⁻¹¹ And pKa is -log Ka = <em>10.87 </em> pH of the solution is:
pH = 10.87 + log₁₀ [0.600] / [0.400]
<em>pH = 11.05</em>
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I hope it helps!
