Write a claim, evidence, reasoning statement to answer the questions below based on the measurements and observations recorded during the lab.
Questions:
1. How does solubility for a gas vary with temperature?
2. How does solubility for a solid vary with temperature?
Some sample data similar to the lab is given below.
Oxygen in Water
\begin{tabular}{|c|c|}
\hline \begin{tabular}{c}
Temperature
$
left({ }^{\circ} C \right)$
\end{tabular} & \begin{tabular}{c}
Concentration
$( mg$ solute/
mL solvent
\end{tabular} \\
\hline 5 & 0.12 \\
\hline 15 & 0.10 \\
\hline 25 & 0.08 \\
\hline
\end{tabular}
Answer (1)
Gas solubility decreases as temperature increases, evidenced by oxygen data.
Increased temperature raises gas molecule kinetic energy, reducing solubility.
Solid solubility generally increases with temperature, though exceptions exist.
Higher temperatures provide energy to break solute bonds, favoring dissolution.
Explanation
Understanding the Task We want to create a claim, evidence, reasoning (CER) statement to explain how temperature affects the solubility of gases and solids, using the provided oxygen data as evidence for gases.
Analyzing the Data The provided data shows the solubility of oxygen gas in water at different temperatures. We can see that as the temperature increases, the concentration of oxygen in the water decreases.
Claim about Gas Solubility Based on the data, we can formulate the following claim about the relationship between temperature and gas solubility: The solubility of a gas in a liquid decreases as the temperature increases.
Evidence for Gas Solubility The evidence from the oxygen data that supports this claim is as follows: At 5°C, the concentration of oxygen is 0.12 mg/mL; at 15°C, the concentration is 0.10 mg/mL; and at 25°C, the concentration is 0.08 mg/mL.
Reasoning for Gas Solubility The reasoning behind this relationship is based on the kinetic molecular theory. As temperature increases, gas molecules have more kinetic energy and are more likely to escape from the liquid phase into the gas phase, thus decreasing the solubility of the gas in the liquid.
General Relationship for Solid Solubility Now, let's consider the relationship between temperature and solid solubility. In general, the solubility of most solids in a liquid increases as the temperature increases. This is because higher temperatures provide more energy for breaking the bonds holding the solid together, allowing it to dissolve more readily in the solvent. However, there are exceptions where the solubility of some solids decreases with increasing temperature.
Claim about Solid Solubility Based on this general knowledge, we can formulate the following claim about the relationship between temperature and solid solubility: The solubility of most solids in a liquid generally increases as the temperature increases, although exceptions exist.
Reasoning for Solid Solubility The reasoning behind this relationship is based on the thermodynamics of dissolution. Dissolving a solid involves breaking solute-solute interactions and solvent-solvent interactions, and forming solute-solvent interactions. If the overall process is endothermic (requires energy), increasing the temperature will favor the dissolution of the solid, thus increasing its solubility.
Comprehensive CER Statement Combining the claims, evidence, and reasoning for both gas and solid solubility, we can create the following CER statement:
Claim: The solubility of a gas in a liquid decreases as the temperature increases, while the solubility of most solids in a liquid generally increases as the temperature increases, although exceptions exist.
Evidence: The solubility of oxygen in water decreases as temperature increases (0.12 mg/mL at 5°C, 0.10 mg/mL at 15°C, and 0.08 mg/mL at 25°C). General scientific knowledge supports that the solubility of most solids increases with temperature.
Reasoning: For gases, increasing temperature increases the kinetic energy of gas molecules, causing them to escape the liquid phase, thus reducing solubility. For most solids, increasing temperature provides more energy to break solute-solute bonds, favoring dissolution if the process is endothermic.
Examples
Understanding how temperature affects solubility is crucial in many real-world applications. For example, in aquatic ecosystems, the amount of dissolved oxygen available for fish and other aquatic life decreases as water temperature rises, which can lead to stress or even death for these organisms. In the food industry, controlling the temperature is essential for dissolving sugar in water to make syrups or for extracting flavors from solids into liquids. In chemical reactions, temperature affects the solubility of reactants, which can influence the rate and yield of the reaction.
