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.
<span>A molecule has one carbon-carbon double bond and four monovalent atoms or groups have two isomers.
</span>
<span>When there is different arrangement of atoms in a compound
but having the save molecular formula, these are called isomers of that
compound. These isomers also have different properties due to the change of arrangement
of atoms or different structure.</span>
Sand and gravel mixture would be easiest to separate based on the size of the particles.
<h3>What are mixtures?</h3>
Mixtures are the composition which can be obtained by the combination of different types of elements.
In the question different types of mixtures are given in which all have same kind of size distribution except sand and gravel. Size of sand is smaller than gravel, so it can be separated by easy physical method like sieving.
Hence, option (d) is correct it means sand and gravel would be easiest to separate.
To know more about mixtures, visit the below link:
brainly.com/question/1917079
Big dogs and short dogs, short hair and long hair, pointy ears and droopy ears
Density is mass over volume. If you put it into a formula it would look like this:
Based on the problem given, you can see that the mass of the aluminum block is 82.0 g and the volume is 12.8 cm3. Just put that into your equation and solve for it:
The answer is then letter C.