## General Chemistry

### Chemistry of Solutions

**9 out of 10**

The concentration of solutions are generally expressed in terms of molarity, molality, normality, and weight percent. The formation of the solutions itself has many ramifications. The solubility of solutes differ considerably from one other. Some of the factors that can influence the solubility include temperature and pressure. Solubility depends on other factors as well. Given below in Figure-1 is a graph which depicts solubility differences of some solutes.

Quite often, the freezing and boiling point changes that are brought about by the dissolved solutes can be predicted reasonably. But this is not always the case.

The predictions and calculations are done for freezing point depression (ΔT_{f}) based on the following formula:

ΔT_{f} = K_{f} m,

where m is the molality and K_{f} is the freezing point depression constant. (K_{f}= 1.86 ^{o}C/*m*)

For boiling point elevation (ΔT_{b}), the calculations are based on the following formula:

ΔT_{b} = K_{b} m,

where m is the molality and K_{b} is the boiling point elevation constant. (K_{b} = 0.512 ^{o}C/*m*)

If the amount of glucose used in Question 7 is doubled, while the same 750 g of water was used, what must have happened to the boiling point of the solution?

A | It doubled |

B | It quadrupled |

C | It decreased slightly |

D | It increased slightly |

**Ans. D**This question is a bit tricky. You may have selected Choice A. But you have to understand what exactly is asked in the question. The question is not asking about the change in boiling point (ΔT). Instead, it asks what happens to the boiling point. It will not double; it will only increase slightly.

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Chemistry of Solutions Flashcard List

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