Solute A associates in water. When 0.7 g of solute A is dissolved in 42.0 gof water, it depresses the freezing point by 0.2°C. The percentage association of solute A in water is :
[Given : Molar mass of A = 93 g mol–1. Molal depression constant of water is 1.86 K kg mol–1.]
Solute A associates in water. When 0.7 g of solute A is dissolved in 42.0 gof water, it depresses the freezing point by 0.2°C. The percentage association of solute A in water is :
[Given : Molar mass of A = 93 g mol–1. Molal depression constant of water is 1.86 K kg mol–1.]
- 50%
- 60%
- 70%
- 80%
The Correct Option is A
Solution and Explanation
The correct option is(D): 80%
Since, ΔTf = ikfm
\(m=]frac{0.7}{93}×\frac{1000}{42}\)
\(0.2=i×1.86×\frac{0.7×1000}{93×42}\)
i = 0.6
\(α=\frac{i=1}{\frac{1}{n}-1}=\frac{0.6-1}{\frac{1}{2}-1}=0.8\)
Hence, percentage association of solute A is 80%.
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Concepts Used:
Water
Water is a chemical compound whose one molecule is composed of 2 atoms of hydrogen and 1 atom of oxygen, giving it the chemical formula: H2O.
Water is also known to be a universal solvent because it can dissolve (solute) almost anything and everything in it. Water is what earth’s hydrosphere is made up of along with 60% of our bodies and in some organisms, the Water content is as high as 90%.
Use of Water:
Water resources are necessary for sustaining life as well as for economic development as well but all of this can lead to making the most of our already limited Freshwater resources. These are the following practices that one can adopt to utilize water more responsibly:
- Reclamation of Water
- Rainwater Harvesting
- Reduce the usage of Water
- Desalination