Question

a student wants to test how water temperature affects the solubility of oxygen gas (o₂). solubility refers to a substance’s ability to dissolve in a solvent, which in this case is water. the data for the experiment is graphed below: graph of oxygen solubility in water at various temperatures, x - axis temperature (°c), y - axis solubility (mg/l) write a claim, evidence, reasoning (cer) paragraph for the graph above:

• claim: make a claim based on the graph above.
• evidence: provide evidence from the graph to support your claim.
• reasoning: explanation of how the evidence supports the claim and what the data and trends mean.

Explanation:

• Claim: The solubility of oxygen gas in water decreases as the temperature of water increases.
• Evidence: The graph titled “Oxygen solubility in water at various temperatures” shows that when the temperature (x - axis) increases from around 5°C to 35°C, the solubility of oxygen (y - axis, measured in mg/L) decreases from approximately 14 mg/L to around 6 mg/L.
• Reasoning: Solubility of gases in liquids is related to the kinetic energy of the gas and liquid molecules. As water temperature rises, water molecules gain kinetic energy, which makes it harder for oxygen gas molecules to stay dissolved (they are more likely to escape the liquid phase). The trend in the graph (negative correlation between temperature and oxygen solubility) aligns with the scientific principle that the solubility of most gases in liquids decreases with an increase in temperature.

Answer:

Claim: The solubility of oxygen gas in water decreases as the temperature of water increases.

Evidence: From the graph, at 5°C, oxygen solubility in water is about 14 mg/L, and as temperature rises to 35°C, solubility drops to around 6 mg/L.

Reasoning: As water temperature increases, water molecules’ kinetic energy rises, reducing the ability of O₂ molecules to remain dissolved (consistent with gas - liquid solubility principles, where most gases’ solubility in liquids decreases with increasing temperature). The graph’s negative trend between temperature and O₂ solubility supports this.