Problem 50 - Chemistry for Allied Health

Question

Write the formula of each base's conjugate acid. a. \(\mathrm{BrO}_{3}^{-}\) b. \(\mathrm{NH}_{3}\) c. \(\mathrm{CH}_{3} \mathrm{COO}^{-}\) d. \(\mathrm{HCO}_{3}^{-}\) e. \(\mathrm{CN}^{-}\) f. \(\mathrm{HPO}_{4}^{2-}\) g. HS- \(\mathrm{h} . \mathrm{SO}_{4}^{2-}\) i. \(\mathrm{CO}_{3}^{2-}\) \(\mathrm{j} . \mathrm{HCO}_{3}^{-}\) k. \(\mathrm{PH}_{3}\)

Step-by-Step Solution

Answer

Add a proton to each base to find its conjugate acid: HBrO₃, NH₄⁺, CH₃COOH, H₂CO₃, HCN, H₂PO₄⁻, H₂S, HSO₄⁻, HCO₃⁻, H₂CO₃, PH₄⁺.

Step 1: Identify the Base

A base is a substance that can accept a proton (a hydrogen ion, H⁺). We need to identify each base from the problem question.

Step 2: Add a Proton

To find the conjugate acid of each base, add one hydrogen ion (H⁺) to the chemical formula of the base. This addition increases the positive charge of the base by +1.

Step 3: Write the Conjugate Acid Formula

For each base provided:- a. Add \[\mathrm{H^{+}} + \mathrm{BrO}_{3}^{-} \rightarrow \mathrm{HBrO}_{3}\]- b. Add \[\mathrm{H^{+}} + \mathrm{NH}_{3} \rightarrow \mathrm{NH}_{4}^{+}\]- c. Add \[\mathrm{H^{+}} + \mathrm{CH}_{3} \mathrm{COO}^{-} \rightarrow \mathrm{CH}_{3} \mathrm{COOH}\]- d. Add \[\mathrm{H^{+}} + \mathrm{HCO}_{3}^{-} \rightarrow \mathrm{H}_{2}\mathrm{CO}_{3}\]- e. Add \[\mathrm{H^{+}} + \mathrm{CN}^{-} \rightarrow \mathrm{HCN}\]- f. Add \[\mathrm{H^{+}} + \mathrm{HPO}_{4}^{2-} \rightarrow \mathrm{H}_{2}\mathrm{PO}_{4}^{-}\]- g. Add \[\mathrm{H^{+}} + \mathrm{HS}^{-} \rightarrow \mathrm{H}_{2}\mathrm{S}\]- h. Add \[\mathrm{H^{+}} + \mathrm{SO}_{4}^{2-} \rightarrow \mathrm{HSO}_{4}^{-}\]- i. Add \[\mathrm{H^{+}} + \mathrm{CO}_{3}^{2-} \rightarrow \mathrm{HCO}_{3}^{-}\]- j. Add \[\mathrm{H^{+}} + \mathrm{HCO}_{3}^{-} \rightarrow \mathrm{H}_{2}\mathrm{CO}_{3}\]- k. Add \[\mathrm{H^{+}} + \mathrm{PH}_{3} \rightarrow \mathrm{PH}_{4}^{+}\]

Step 4: Confirmation

Double-check the charge conservation and correct molecular structure for the conjugate acids found in the previous step to ensure each conjugate acid is formed correctly.

Key Concepts

Acid-Base Reactions

Acid-base reactions are fundamental chemical processes where an acid donates a proton (H⁺) and a base accepts it. In these reactions, two things happen simultaneously. The acid becomes its conjugate base, and the base becomes its conjugate acid. This concept is crucial for understanding the behavior of substances in a solution. Consider the acid as a proton donor: when it loses this proton, it transforms into its conjugate base. The base, on the other hand, acts as a proton acceptor. When it gains a proton, it becomes its conjugate acid. These reactions are reversible, often reaching an equilibrium state where the forward and reverse reactions occur at equal rates. This equilibrium is central to many natural and industrial processes, like acidification of oceans and processes in our bodies. Remember, the strength of acids and bases varies widely, affecting how readily they donate or accept protons.

Proton Transfer

Proton transfer is the essential process that occurs during acid-base reactions. It involves the transfer of a proton from an acid to a base. This proton is essentially a hydrogen ion (H⁺), which carries a positive charge. This transfer is the main reason why chemical formulas of acids and bases change during reactions. For example, when an acid donates a proton, its formula changes, leaving behind its conjugate base. The base, after accepting a proton, becomes the conjugate acid. This movement of protons is what makes the chemical reactions dynamic and is a key reason why such reactions can shift equilibrium in a solution. Understanding proton transfer helps predict the outcomes of reactions and is fundamental in fields such as biochemistry and pharmacology, where the ability of molecules to donate or accept protons affects their function.

Chemical Formulas

Chemical formulas represent the types and numbers of atoms in a molecule. When identifying conjugate acids, it's essential to alter these formulas to reflect the addition of a proton. For instance, for a base like \(\mathrm{NH}_3\), after accepting a proton, it becomes \(\mathrm{NH}_4^+\). The chemical formula is slightly altered to show the increase in hydrogen atoms and the overall charge change.Chemical formulas serve as a shorthand to convey complex information about the composition and structure of molecules. Understanding them is crucial for predicting how substances will interact in chemical reactions. Each atom's symbol, and any associated charge, provides valuable information about the molecule's potential reactivity and the stability of its conjugate partners. This understanding is especially useful in chemistry labs or industries where predicting reactions is necessary for safety and efficacy.

Charge Conservation

Charge conservation is a fundamental principle in chemistry, stating that the total charge before and after a chemical reaction must remain constant. When a base accepts a proton to form a conjugate acid, its charge typically increases by +1 due to the addition of a positively charged hydrogen ion (H⁺). For example, when \(\mathrm{CN}^{-}\) accepts a proton, it becomes \(\mathrm{HCN}\), moving from a -1 charge to an overall neutral charge.Ensuring charge conservation is critical for balancing chemical equations correctly. It helps chemists confirm that chemical reactions are balanced not only in terms of atoms but also in terms of charge. This balancing is pivotal when predicting how reactions proceed and ensuring that calculations of reactants and products are accurate. Misunderstanding charge balance can lead to errors in chemical predictions, proving the importance of this concept in both theoretical and practical chemistry.