This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Welcome back — been a while! Let's pick up where you left off. 1. What is the concentration of OH in a solution with an H^+ concentration of 1.3 × 10^-4 M? Step 1: Use the ion product constant for water, K_w. K_w = [H^+][OH^-] At 25^, K_w = 1.0 × 10^-14. Step 2: Substitute the given [H^+] and solve for [OH^-]. 1.0 × 10^-14 = (1.3 × 10^-4 M)[OH^-] [OH^-] = 1.0 × 10^-141.3 × 10^-4 M [OH^-] ≈ 7.69 × 10^-11 M The concentration of OH^- is 7.69 × 10^-11 M. 2. What is the pH of 0.1 M hydrochloric acid? Step 1: Hydrochloric acid (HCl) is a strong acid, meaning it dissociates completely in water. HCl H^+ + Cl^- Therefore, the concentration of H^+ ions is equal to the initial concentration of HCl. [H^+] = 0.1 M Step 2: Calculate the pH using the formula pH = -[H^+]. pH = -(0.1) pH = -(10^-1) pH = 1 The pH of 0.1 M hydrochloric acid is 1. 3. When pH falls by 1 unit, what is the change in the hydrogen ion concentration? Step 1: Recall the definition of pH. pH = -[H^+] This can be rearranged to [H^+] = 10^-pH. Step 2: Let the initial pH be pH_1 and the initial hydrogen ion concentration be [H^+]_1. [H^+]_1 = 10^-pH_1 Step 3: When pH falls by 1 unit, the new pH is pH_2 = pH_1 - 1. The new hydrogen ion concentration is [H^+]_2. [H^+]_2 = 10^-pH_2 = 10^-(pH_1 - 1) [H^+]_2 = 10^-pH_1 + 1 [H^+]_2 = 10^1 × 10^-pH_1 [H^+]_2 = 10 × [H^+]_1 When pH falls by 1 unit, the hydrogen ion concentration increases by a factor of 10. 4. Which equation describes the relationship between pH and pK? The relationship between pH and pK (specifically pK_a) for a buffer solution is described by the Henderson-Hasselbalch equation: pH = pK_a + ([conjugate base][weak acid]) 5. What determines the pH of buffer? The pH of a buffer solution is primarily determined by two factors: • The pK_a of the weak acid component of the buffer system. • The ratio of the concentration of the conjugate base to the concentration of the weak acid in the buffer solution. 6. When is a buffer most effective? A buffer is most effective when the concentration of the weak acid is approximately equal to the concentration of its conjugate base. This occurs when the pH of the buffer is equal to the pK_a of the weak acid. Buffers are also more effective when the absolute concentrations of the weak acid and conjugate base are high. 7. What do you understand by the term "buffering capacity"? Buffering capacity refers to the amount of acid or base that a buffer solution can neutralize before its pH changes significantly. It is determined by the absolute concentrations of the weak acid and its conjugate base present in the solution. A higher concentration of buffer components means a greater buffering capacity. Send me the next one 📸