Q32. Identify the compound whose solubility is least affected by temperature.

Background

Topic: Solubility and Temperature Dependence

This question tests your understanding of how the solubility of different ionic compounds in water changes with temperature. Some salts show a strong dependence on temperature, while others do not.

Key Terms and Concepts:

• Solubility: The amount of solute that can dissolve in a given amount of solvent at a specific temperature.

• Temperature Dependence: For many solids, solubility increases with temperature, but for some, it remains nearly constant.

Step-by-Step Guidance

1. Examine the solubility curves for each compound on the provided graph. Look for the compound whose solubility line is the flattest (shows the least change) as temperature increases from 0°C to 100°C.

2. Compare the slopes of the lines for each compound. A steeper slope means greater temperature dependence, while a nearly horizontal line means little to no dependence.

3. Focus on the compounds listed in the answer choices: CaCl2, K2Cr2O7, KClO3, Pb(NO3)2, and NaCl. Find each on the graph and observe how much their solubility changes with temperature.

4. Identify which compound's solubility curve is closest to being horizontal across the temperature range.

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Q61. Using the tabulated data of the concentration of AB versus time and the plot of 1/[AB] with respect to time (s) for this reaction: AB (g) → A (g) + B (g). Predict the concentration of AB at 210 seconds.

Background

Topic: Reaction Order and Integrated Rate Laws

This question tests your ability to use integrated rate laws and graphical data to predict concentrations at a given time for a second-order reaction.

Key Terms and Formulas:

• Second-Order Reaction: A reaction where the rate depends on the square of the concentration of one reactant, or the product of two reactant concentrations.

• Integrated Rate Law for Second-Order (single reactant):

• Slope of the Line: In a plot of vs. time, the slope equals the rate constant .

Step-by-Step Guidance

1. From the graph, note the equation of the line: , where and (time in seconds).

2. To find at s, substitute into the equation to solve for .

3. Once you have the value for , recall that .

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