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CaHeK987 [17]
2 years ago
9

Quinine is a natural product extracted from the bark of the cinchona tree, which is native to South America. Quinine is used as

an antimalarial agent. When 3.28 g of quinine is dissolved in 25.0 g of cyclohexane, the freezing point of the solution is lowered by 8.43 °
c. The freezing point and Kf constant for cyclohexane can be found here.
Calculate the molar mass of quinine.
Chemistry
1 answer:
evablogger [386]2 years ago
5 0
For the answer to the question above, <span>The formula for freezing point depression is </span>
<span>ΔTf = mkfi </span>

<span>kf is the freezing point constant </span>
<span>i is the Van't Hoff factor which in this case is 1 </span>
<span>m is molality (moles of solute/kg of solvent) </span>
<span>ΔTf is temperature change </span>

<span>ΔTf is 2.17 °C, the molality is the amount of solute Quinine </span>
<span>in the solvent cyclohexane. We cannot calculate moles therefore we need to substitute moles with g/mm. </span>

<span>moles = g/mm so molality=(g/mm)/kg </span>
<span>molality = (0.845/mm)/0.025 = 33.8/mm </span>

<span>2.17 = 33.8/mm(20.8) rearrange </span>

<span>mm = (33.8/2.17)(20.8) = 324g/mol</span>
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For example, H_{2}O is a polar covalent compound. Partial opposite charges tend to develop on the atoms of a polar covalent compound.

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In this type of bond, dipole-dipole attractive interactions tend to take place. And, strength of hydrogen bonds is very weak.

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