Analyze and Evaluate Scientific Explanations and Predictions Practice Test

A thin, nonreactive polymer film separates two aqueous compartments containing KCl at the same concentration (0.10 M) but different temperatures: side 1 at 298 K and side 2 at 310 K. The film is permeable to ions and water, and no external voltage is applied. A student predicts a sustained net electric current will flow from the hot side to the cold side solely due to the temperature difference. Assuming both compartments remain electrically neutral and that diffusion is driven by chemical potential gradients, which evaluation is most consistent with these principles?

Given: For an ideal solute, $\mu = \mu^\circ + RT\ln a$; for dilute solutions, $a\approx$ concentration.

A researcher tests whether dissolved CO$_2$ (aq) measurably acidifies water in a sealed 1.0 L vessel at 25°C. The vessel initially contains pure water equilibrated with 1.0 atm N$_2$ (no CO$_2$). The headspace gas is then replaced with 0.20 atm CO$_2$ (balance N$_2$) and allowed to re-equilibrate without changing temperature. Assume Henry’s law for CO$_2$: $\text{CO}2(\text{aq})=k_H P{\text{CO}_2}$ with $k_H=3.3\times10^{-2}$ M/atm, and that each dissolved CO$_2$ molecule contributes at most one H$^+$ via $\text{CO}_2+\text{H}_2\text{O}\rightleftharpoons \text{H}^+ + \text{HCO}_3^-$. Which prediction is most consistent with these principles regarding the final pH compared with the initial pH (7.0)?