What is the hypothetical van’t Hoff factor of magnesium nitrate, Mg(NO3)2?
The Correct answer and Explanation is:
The hypothetical van’t Hoff factor (iii) for magnesium nitrate, Mg(NO3)2\text{Mg(NO}_3\text{)}_2Mg(NO3)2, is 3.
Explanation:
The van’t Hoff factor (iii) is a measure of the number of particles into which a solute dissociates in a solution. It plays a crucial role in colligative properties, such as boiling point elevation and freezing point depression, which depend on the number of solute particles in a solution rather than their identity.
For magnesium nitrate, Mg(NO3)2\text{Mg(NO}_3\text{)}_2Mg(NO3)2, the formula indicates that one magnesium ion (Mg2+\text{Mg}^{2+}Mg2+) and two nitrate ions (NO3−\text{NO}_3^{-}NO3−) are produced when it dissociates in solution. The dissociation can be represented as follows:Mg(NO3)2(s)→Mg2+(aq)+2 NO3−(aq)\text{Mg(NO}_3\text{)}_2 (s) \rightarrow \text{Mg}^{2+} (aq) + 2 \, \text{NO}_3^{-} (aq)Mg(NO3)2(s)→Mg2+(aq)+2NO3−(aq)
In this reaction, the magnesium nitrate dissolves to yield one magnesium ion and two nitrate ions. Thus, if we count the total number of particles generated:
- From one formula unit of Mg(NO3)2\text{Mg(NO}_3\text{)}_2Mg(NO3)2, we get:
- 1 Mg2+\text{Mg}^{2+}Mg2+
- 2 NO3−\text{NO}_3^{-}NO3−
This results in a total of 1+2=31 + 2 = 31+2=3 ions. Hence, the van’t Hoff factor iii for magnesium nitrate is:i=1+2=3i = 1 + 2 = 3i=1+2=3
In summary, the van’t Hoff factor iii provides important insights into the behavior of solutes in solutions, particularly in predicting the extent of colligative effects. Knowing that magnesium nitrate dissociates into three particles allows chemists to calculate changes in properties such as vapor pressure, boiling point, and osmotic pressure more accurately when this compound is dissolved in water or other solvents.