Questions: Module 1 - Homework (Chapters 1 and 2 ) Question 26 of 60 (1 point) I Question Attempt: 1 of Unlimited - Sample A is a solid yellow cube with a total mass of 50.0 g. The cube is divided into two smaller 25.0 g subsamples, and the minimum volume of water needed to dissolve each subsample is measured. The first subsample just barely dissolved in 101 mL of water, the second in 92 mL. When the experiment is repeated with a new 50.0 g sample, the minimum volume of water required to dissolve the two subsamples is 89 mL and 93 mL. - Sample B is 100 mL of a clear liquid. The liquid is heated in a flask until it boils, which starts to happen at 66.2°C. As the liquid boils, the temperature continues to rise, until the last of the liquid boils away at 76.0°C. Is sample A made from a pure substance or a mixture?

Module 1 - Homework (Chapters 1 and 2 )
Question 26 of 60 (1 point) I Question Attempt: 1 of Unlimited
- Sample A is a solid yellow cube with a total mass of 50.0 g. The cube is divided into two smaller 25.0 g subsamples, and the minimum volume of water needed to dissolve each subsample is measured. The first subsample just barely dissolved in 101 mL of water, the second in 92 mL. When the experiment is repeated with a new 50.0 g sample, the minimum volume of water required to dissolve the two subsamples is 89 mL and 93 mL.
- Sample B is 100 mL of a clear liquid. The liquid is heated in a flask until it boils, which starts to happen at 66.2°C. As the liquid boils, the temperature continues to rise, until the last of the liquid boils away at 76.0°C.

Is sample A made from a pure substance or a mixture?

Transcript text: Module 1 - Homework (Chapters 1 and 2 ) Question 26 of 60 (1 point) I Question Alitmpi: 1 of Unilimited - Sample A is a solid yellow cube with a total mass of 50.0 g . The cube is divided into two smaller 25.0 g subsamples, and the minimum volume of water needed to dissolve each subsample is measured. The first subsample just barely dissolved in $101 . \mathrm{mL}$ of water, the second in $92 . \mathrm{mL}$. When the experiment is repeated with a new 50.0 g . sample, the minimum volume of water required to dissolve the two subsamples is $89 . \mathrm{mL}$ and $93 . \mathrm{mL}$. - Sample B is $100 . \mathrm{mL}$ of a clear liquid. The liquid is heated in a flask until it boils, which starts to happen at $66.2^{\circ} \mathrm{C}$. As the liquid boils, the temperature continues to rise, until the last of the liquid boils away at $76.0^{\circ} \mathrm{C}$. Is sample A made from a pure substance or a mixture?

Solution

Solution Steps

Step 1: Analyze the Dissolution of Sample A

Sample A is divided into two 25.0 g subsamples, and the minimum volume of water needed to dissolve each subsample is measured. The first subsample dissolves in 101 mL of water, and the second in 92 mL. When the experiment is repeated with a new 50.0 g sample, the subsamples dissolve in 89 mL and 93 mL of water, respectively.

Step 2: Evaluate Consistency in Dissolution

For a pure substance, the solubility should be consistent under the same conditions. However, the volumes of water required to dissolve the subsamples vary significantly (101 mL, 92 mL, 89 mL, and 93 mL). This inconsistency suggests that the solubility is not uniform, which is a characteristic of a mixture rather than a pure substance.

Step 3: Conclusion on Sample A

Given the varying solubility, it is likely that Sample A is a mixture. A pure substance would typically have a consistent solubility under identical conditions.