First, we will get the average pH of the two given values:
average pH = (6.4+8) / (2) = 7.2
At this average pH, the concentration of the acid from the phenol red is equal to the concentration of the base.
pH = 7.2
[H+] = 10^(-7.2) = 6.3 * 10^-8
Phenol red has the general formula HA, this gives us:
HA <.......> H+ + A-
At pH = 7.2, [H+] = [A-]
<span>Ka = [H+][A-]/ [HA]
</span>Ka = [H+] = <span>6.3 x 10^-8</span>
Answer:
<u><em>Structure:</em></u>
<em>Differences- </em>A polymer is a collection of a large number of molecules whereas a monomer is a single molecule.
A monomer is a single molecule, which has the ability to chemically bond with other monomers in a long chain. A polymer is a chain that is made when monomers bind with other monomers.
<em>Similarities-</em> They are both molecules
<u><em>Properties:</em></u>
<em> Differences- </em>Monomers have polyfunctionality, which is the capacity to form chemical bonds to at least two other monomer molecules. Polymers are chemically unreactive, solids at room temperature, malleable, tough, and are electrical insulators.
<em>Similarities- </em>They both makeup larger forms of matter.
<u><em>Intermolecular Forces</em></u>
<em>Differences: </em>Polymers are held together by covalent bonds, hydrogen bonds, and dispersion bonds. Monomers are <u><em>only</em></u> held together by hydrogen bonds.
<em>Similarities: </em>They can both be bonded together by hydrogen bonds.
<span>Answer: 100 ml
</span>
<span>Explanation:
1) Convert 1.38 g of Fe₂S₃ into number of moles, n
</span>i) Formula: n = mass in grass / molar mass
<span>
ii) molar mass of </span><span>Fe₂S₃ =2 x 55.8 g/mol + 3 x 32.1 g/mol = 207.9 g/mol
</span>
iii) n = 1.38 g / 207.9 g/mol = 0.00664 moles of <span>Fe₂S₃
</span>
<span>2) Use the percent yield to calculate the theoretical amount:
</span>
<span>65% = 0.65 = actual yield/ theoretical yield =>
</span>theoretical yield = actual yield / 0.65 = 0.00664 moles / 0.65 = 0.010 mol <span>Fe₂S₃</span><span>
3) Chemical equation:
</span>
<span> 3 Na₂S(aq) + 2 FeCl₃(aq) → Fe₂S₃(s) + 6 NaCl(aq)
4) Stoichiometrical mole ratios:
</span>
<span>3 mol Na₂S : 2 mol FeCl₃ : 1 mol Fe₂S₃ : 6 mol NaCl
5) Proportionality:
</span>2moles FeCl₃ / 1 mol Fe₂S₃ = x / 0.010 mol Fe₂S₃
<span>
=> x = 0.020 mol FeCl₃
6) convert 0.020 mol to volume
</span>
<span>i) Molarity formula: M = n / V
</span>
<span>ii) V = n / M = 0.020 mol / 0.2 M = 0.1 liter = 100 ml
</span>
Answer:
344 nm is the longest wavelength of radiation with enough energy to break carbon-carbon bonds.
Explanation:
,ΔH = 348 kJ/mol
Energy required to break 1 mole of C-C bond = 348 kJ
Energy required to break 1 C-C bond = E
Energy related with the wavelength of light is given by Planck's equation:
344 nm is the longest wavelength of radiation with enough energy to break carbon-carbon bonds.
