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Ruth was doing some research when she learned that solute-solvent mixtures are e

ID: 986370 • Letter: R

Question

Ruth was doing some research when she learned that solute-solvent mixtures are exothermic processes. Ruth was asked to determine which of the following ions in solution should have the most exothermic Delta H_hydration or mixing? What ion did Ruth select? Na^+ Al^3+ Sr^2+ Mg^2+ Ca^2+ Maria is working in a research lab and is asked to use gas chromatography (GC) to separate and identify some compounds she has been working with. The solvent she is using in the separation experiment is hexane, C_6H_14, could you identify the compound that Maria expect to come out first of the gas chromatograph? CH_3CH_2CH_2CH_3 CH_3CI HOCH_2CH_2OH HCL CH_3CH_2OH

Explanation / Answer

1) Al3+

Heat of hydration is inversely proportional to size of the cation. The attractions are stronger the smaller the ion.Among the given ions Al3+ is the smallest ion. So its hydration enthalpy is more negative ( more exothermic).

2) a. CH3CH2CH2CH3

Among the four compounds , butane is the non polar compound and solvent hexane is also non-polar. As we know like dissolves like, therefore non polar butane comes first in separation by using hexane.