Chapter 17, Problem 11TE

You take $\text{50 mL}$ of water and combine it with $\text{50 mL}$ of purified alcohol and you get a total of $\text{98 mL}$ of mixture. Explain.

Solution

To determine: The reason for getting a volume of $\text{98 mL}$ on mixing $\text{50 mL}$ of water and of purified alcohol

Answer:

Due to the difference in the size of molecules of two liquids, when they are mixed together, water molecules occupy the spaces between the ethanol molecules.

Explanation:

When $\text{50 mL}$ of water is combined with $\text{50 mL}$ of purified alcohol, the total volume obtained is $\text{98 mL}$ not $\text{100 mL}$ , it is due to the reason that there is difference in size of molecules of ethanol and water. The size of ethanol molecules is larger than the molecules of water. Molecules are generally considered to be spherical. So when spherical water molecules are packed, small empty spaces are left. Some smaller water molecules occupy those spaces and as a result the total volume is expected to be less than $\text{100 mL}$.

Conclusion:

Therefore, due to difference in sizes of the molecules of the two liquids, the total volume is less than the actual volume.