IMAT Chemistry: Descriptive Questions

Explain the conceptual difference between isotopes and allotropes, providing an example for each.

Explain why real gases deviate from the behavior predicted by the Ideal Gas Law ($$PV=nRT$$) , especially under certain conditions.

Explain the difference between an electrolyte and a non-electrolyte. How does this difference affect the colligative properties of a solution?

What is the fundamental difference between a strong acid and a weak acid? Use the concept of dissociation in your explanation.

What is the conceptual difference between an oxidizing agent and a reducing agent in a redox reaction?

What determines whether a covalent bond between two atoms will be polar or nonpolar? Explain with reference to electronegativity.

Define activation energy. Explain how a catalyst increases the rate of a chemical reaction with reference to activation energy.

State Le Châtelier's principle. For the reversible reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$ (which is exothermic) , predict how the equilibrium position will shift if (a) the pressure is increased, and (b) the temperature is increased.

Describe the periodic trend for atomic radius and electronegativity as you move from left to right across a period and from top to bottom down a group.

Define structural isomers. Draw and name two structural isomers with the molecular formula $C_4H_{10}$.

Explain the difference between structural isomers and stereoisomers. Provide an example of a molecule that can exhibit stereoisomerism.

Identify the functional group present in each of the following molecules: (a) Ethanol ($CH_3CH_2OH$), (b) Acetic acid ($CH_3COOH$), and (c) Ethyl acetate ($CH_3COOCH_2CH_3$).

Compare an addition reaction with a substitution reaction, providing an example for each type of reaction.

Define first ionization energy. Explain why the first ionization energy generally increases from left to right across a period.

The halogens (Group 17) are strong oxidizing agents. How does their oxidizing strength change as you go down the group from $F_2$ to $I_2$? Explain this trend.

Balance the following redox reaction in an acidic solution using the half-reaction method: $$Cr_2O_7^{2-}(aq) + I^-(aq) \rightarrow Cr^{3+}(aq) + I_2(s)$$

It takes 25.0 mL of a 0.100 M $NaOH$ solution to completely neutralize 20.0 mL of an $HCl$ solution. What is the concentration of the $HCl$ solution?

What is a buffer solution, and how does it work? Use an acetic acid/acetate buffer ($CH_3COOH / CH_3COO^-$) to explain.

Write the expression for the equilibrium constant, $K_c$, for the reaction: $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$. What does a very large value of $K_c$ indicate?

List the three main types of intermolecular forces in order of generally increasing strength. For each, describe what causes the attraction.

State Dalton's Law of Partial Pressures. If a container holds nitrogen ($N_2$) at 0.8 atm and oxygen ($O_2$) at 0.2 atm, what is the total pressure?

What are colligative properties? Name two examples.

Define 'limiting reactant' and 'excess reactant'. For the reaction $2H_2(g) + O_2(g) \rightarrow 2H_2O(l)$, if 5.0 moles of $H_2$ react with 3.0 moles of $O_2$, which is the limiting reactant?

State Hess's Law. Explain how it can be used to determine the enthalpy change of a reaction that is difficult to measure directly.

What is the difference between a homogeneous and a heterogeneous catalyst? Provide an example of each.

What is the difference between valence electrons and outermost shell electrons?

What is the fundamental difference between a physical change and a chemical change? Provide one example of each.

What is the difference between distillation and fractional distillation?

Why are aromatic compounds like benzene exceptionally stable compared to other unsaturated hydrocarbons like alkenes?

Explain why carboxylic acids (e.g., acetic acid) are significantly more acidic than alcohols (e.g., ethanol).

Why do enantiomers have identical physical properties but often vastly different biological activities?

Explain why ethers generally have much lower boiling points than alcohols of similar molecular mass.

What is the correct and safe procedure for diluting concentrated sulfuric acid ($H_2SO_4$)? Explain the reason for this precaution.

What is the difference between an element and a compound?

What are the main advantages and disadvantages of a hydrogen fuel cell?

What are the two main factors that cause real gases to deviate from ideal gas behavior?

What is the relationship between a weak acid and its conjugate base in terms of strength?

What are the three rules/principles that govern how electrons fill orbitals in an atom? Briefly describe each.

List two characteristic properties of transition metals that distinguish them from main group metals.

What is a precipitation reaction? Write the balanced net ionic equation for the precipitation reaction that occurs when aqueous solutions of silver nitrate ($AgNO_3$) and sodium chloride ($NaCl$) are mixed.