26. B
27. D
28. C
Hope this helped ☺️
The attachments dont work, they say that they have been taken down or sum... ?
Answer is: coefficient is one.
Chemical reaction: SiO₂ + 4HF → SiF₄ + 2H₂O.
Reaction is balanced when there are equal numbers of elements in both side of the chemical reaction.
HF - hydrofluoric acid, <span>highly corrosive, dissolves many materials.</span>
SiF₄ - silicon tetrafluoride.
Answer:
3.62x10⁻⁷ = Kb
Explanation:
The acid equilibrium of a weak acid, HX, is:
HX + H₂O ⇄ X⁻ + H₃O⁺
Where Ka = [X⁻] [H₃O⁺] / [HX]
And basic equilibrium of the conjugate base, is:
X⁻ + H₂O ⇄ OH⁻ + HX
Where Kb = [OH⁻] [HX] / [X⁻]
To convert Ka to Kb we must use water equilibrium:
2H₂O ⇄ H₃O⁺ + OH⁻
Where Kw = 1x10⁻¹⁴ = [OH⁻] [H₃O⁺]
Thus, we can obtain:
Kw = Ka*Kb
Solving for Kb:
Kw / Ka = Kb
1x10⁻¹⁴ / 2.76x10⁻⁸ =
3.62x10⁻⁷ = Kb
Of course we would experience them.
