Tutor profile: Omair H.
If a reaction has an increase in entropy, what can be said about it? A. The reaction is always spontaneous B. The reaction is always nonspontaneous C. The reaction is spontaneous above a specific temperature D. The reaction is spontaneous below a specific temperature
C. Using the following thermodynamics formula, ΔG = ΔH − TΔS, we can determine the spontaneity of the reaction. If entropy is increasing, that means that ΔS is +. assuming ΔH is constant, we can determine that as the value of T (the only changing value) increases, the product TΔS will become progressively larger. At a large T value, we have a large positive TΔS. Unchanging ΔH minus increasingly large, positive TΔS will result in a negative ΔG value at high temperatures. In other words, the reaction is spontaneous (-ΔG) at high temperatures.
Which of the following solutions would create a buffer solution? A. NaI, HI B. NaCH3COO, CH3COOH
B. NaCH3COO, CH3COOH One of the most common ways to form a buffer solution is to mix a weak acid with its conjugate base (or a weak base with its conjugate acid). Acetic acid (CH3COOH) is a weak acid, and its conjugate base is the deprotonated form, which is the ion itself. This solution will contain enough of the conjugate base to bind weakly with any H+ atoms that may be added, so it is a basic buffer that buffers against acidic solutions. The NaI, HI combination would not form a buffer because hydroiodic acid is a strong acid. The conjugate base I- would not bind easily with any added hydrogen ions.
Explain how each of the following molecules will pass through the cell membrane. What is each type of transport called? A. carbon dioxide B. water C. sodium ion (Na+)
A. Carbon dioxide is a small, nonpolar molecule. It will passively move through the cell membrane via simple diffusion. CO2 is able to pass through the hydrophilic portion of the cell membrane (the phospholipid heads), and it can also pass through the hydrophobic portion of the cell membrane (the phospholipid tails). B. Water is a small, polar molecule. It will pass through the cell membrane via osmosis. Osmosis is the passive movement of water to an area of lower water concentration. Passive means that it does not require additional energy. Water is small enough to passively move through the lipid membrane bilayer. C. Sodium ion (Na+) is a positively charged atom that will pass through the cell membrane using facilitated diffusion. Because it is charged, it cannot positively interact with the phospholipids, especially the hydrophobic portions. Facilitated diffusion means that Na+ will pass through a transport protein that requires no additional energy. This process is also passive, as the ion will move down the concentration gradient.
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