Pharm-D Admission Test Chemistry Flashcards

24 sample cards from the Chemistry deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. State Avogadro's law and Dalton's law of partial pressures.

   Avogadro's law: at constant T and P, equal volumes of gases contain equal numbers of molecules. Dalton's law: total pressure of a gas mixture equals the sum of the partial pressures of its components (P_total = P1 + P2 + ...).

2. Under what conditions do real gases deviate most from ideal behavior, and why?

   At high pressure and low temperature, because under these conditions intermolecular forces become significant and the molecular volume is no longer negligible compared to the container volume.

3. Define vapor pressure of a liquid and state how it changes with temperature.

   Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature; it increases as temperature increases.

4. Define the boiling point of a liquid in terms of vapor pressure.

   The boiling point is the temperature at which the vapor pressure of the liquid becomes equal to the external (atmospheric) pressure.

5. What is the difference between evaporation and boiling?

   Evaporation is a surface phenomenon occurring at any temperature below the boiling point; boiling occurs throughout the bulk of the liquid at a specific temperature where vapor pressure equals external pressure.

6. Distinguish between crystalline and amorphous solids.

   Crystalline solids have a regular, repeating long-range ordered arrangement of particles, sharp melting points, and are anisotropic; amorphous solids have irregular short-range order, melt over a range, and are isotropic.

7. Define a unit cell and a crystal lattice.

   A crystal lattice is the regular three-dimensional arrangement of points (particles) in space; a unit cell is the smallest repeating unit that, when repeated, generates the entire crystal lattice.

8. How many atoms per unit cell are in simple cubic, body-centered cubic (BCC), and face-centered cubic (FCC) lattices?

   Simple cubic: 1 atom; BCC: 2 atoms; FCC: 4 atoms per unit cell.

9. Define enthalpy (H) and enthalpy change of reaction (delta H).

   Enthalpy is the total heat content of a system at constant pressure (H = U + PV). Delta H is the heat absorbed or released during a reaction at constant pressure (delta H = H_products - H_reactants).

10. What is the difference between an exothermic and an endothermic reaction in terms of delta H?

    Exothermic reactions release heat and have a negative delta H (delta H < 0); endothermic reactions absorb heat and have a positive delta H (delta H > 0).

11. State Hess's law of constant heat summation.

    The total enthalpy change of a reaction is the same whether it occurs in one step or several steps, depending only on the initial and final states, not the path taken.

12. State the first law of thermodynamics and its mathematical expression.

    Energy can neither be created nor destroyed, only converted from one form to another. Mathematically: delta U = q + w, where delta U is change in internal energy, q is heat added to the system, and w is work done on the system.

13. Define internal energy (U) of a system.

    Internal energy is the total of all kinetic and potential energies of the particles in a system; its absolute value cannot be measured, only the change (delta U) is determined.

14. State the law of mass action.

    At constant temperature, the rate of a chemical reaction is directly proportional to the product of the molar concentrations of the reactants, each raised to a power equal to its coefficient in the balanced equation.

15. For the reaction aA + bB <-> cC + dD, write the equilibrium constant expression Kc.

    Kc = ([C]^c [D]^d) / ([A]^a [B]^b), where the brackets denote equilibrium molar concentrations.

16. State Le Chatelier's principle.

    If a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium shifts in the direction that tends to counteract (relieve) the imposed change.

17. According to Le Chatelier's principle, how does increasing pressure affect a gaseous equilibrium?

    Increasing pressure shifts the equilibrium toward the side with fewer moles of gas; if both sides have equal moles of gas, pressure has no effect on the position of equilibrium.

18. How does increasing temperature affect the equilibrium of an exothermic reaction?

    For an exothermic reaction (heat is a product), increasing temperature shifts the equilibrium backward (toward reactants), decreasing the value of Kc.

19. Why does a catalyst not change the position of equilibrium?

    A catalyst speeds up the forward and reverse reactions equally, so it lets equilibrium be reached faster but does not change Kc or the equilibrium concentrations.

20. Define solubility product (Ksp) for a sparingly soluble salt.

    Ksp is the equilibrium constant for the dissolution of a sparingly soluble ionic solid; it equals the product of the molar concentrations of its ions, each raised to the power of its stoichiometric coefficient, in a saturated solution.

21. Write the Ksp expression for a salt of type AB2 (e.g., CaF2) that dissociates into A2+ and 2B-.

    For CaF2 <-> Ca2+ + 2F-, Ksp = [Ca2+][F-]^2. If solubility is s, then Ksp = (s)(2s)^2 = 4s^3.

22. How is the ionic product used to predict precipitation relative to Ksp?

    If the ionic product > Ksp, precipitation occurs (solution is supersaturated); if ionic product = Ksp, the solution is just saturated; if ionic product < Ksp, no precipitate forms (unsaturated).

23. What is the common ion effect?

    The suppression of the ionization (or solubility) of a weak electrolyte or sparingly soluble salt caused by adding a strong electrolyte that provides an ion common to the equilibrium, shifting it backward per Le Chatelier's principle.

24. Explain how the common ion effect decreases the solubility of AgCl when NaCl is added.

    Added NaCl increases the Cl- concentration; to keep Ksp = [Ag+][Cl-] constant, the equilibrium AgCl <-> Ag+ + Cl- shifts left, precipitating AgCl and reducing its solubility.

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