Answer:
0.12 M hydrofluoric acid + 0.17 M potassium fluoride
Explanation:
To make a buffer, you must to have an aqueous mixture of a weak acid and its conjugate base or vice versa.
Knowing that:
0.32 M calcium chloride + 0.27 M sodium chloride: <em>is not a good buffer system </em>because CaCl₂ and NaCl are both salts.
0.35 M ammonia + 0.36 M calcium hydroxide <em>is not a good buffer system </em>because ammonia is a weak base but calcium hydroxide is a strong base
0.19 M barium hydroxide + 0.28 M barium chloride <em>is not a good buffer system </em>because Ba(OH)₂ is a strong base.
0.12 M hydrofluoric acid + 0.17 M potassium fluoride <em>is a good buffer system </em>because HF is a weak acid and KF (F⁻ in aqueous medium), is its conjugate base
0.20 M hydrobromic acid + 0.22 M sodium bromide <em>is not a good buffer system </em>because HBr is a strong acid.
The empirical formula : C₂Cl₇
The molecular formula : C₁₀Cl₃₅
<h3>Further explanation</h3>
Given
8.81 g Carbon
91.2 g Chlorine
Molar Mass: 1362.5 g/mol
Required
The empirical formula and molecular formula
Solution
Mol ratio :
C = 8.81 g : 12.011 g/mol =0.733
Cl = 91.2 g : 35,453 g/mol = 2..572
Divide by 0.733
C : Cl = 1 : 3.5 = 2 : 7
The empirical formula : C₂Cl₇
(The empirical formula)n = the molecular formula
(C₂Cl₇)n = 1362.5
(2x12.011+7x35.453)n=1362.5
(272.193)n=1362.5
n = 5
NH3 = 14 +3*1=17 g/mol
Mass = mol * molar mass = 0.687 * 17= 11.679 g
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