1.) a. The formula for the conjugate base of H2SO3 is The formula for the conjugate acid of H2PO4- is Compare the following: Acid 1: hydrofluoric acid, HF Acid 2: hydrosulfuric acid, H2S Acid 3: carbonic acid, H2CO3 What is the formula for the weakest acid ? b. C. Compare the conjugate bases of these three acids. Acid 1: hypochlorous acid, HCIO Acid 2: phosphoric acid, H3PO4 Acid 3: hydrofluoric acid, HF What is the formula for the weakest conjugate base? d. e. f. Compare the conjugate bases of these three acids. Acid 1: hydrocyanic acid, HCN Acid 2: carbonic acid, H2CO3 Acid 3: hydrogen sulfite, HSO3- What is the formula for the strongest conjugate base? What is the hydronium ion concentration in an aqueous nitric acid solution with a pH of 3.730? [H3O+] = M What is the hydronium ion concentration in an aqueous nitric acid solution that has a pOH of 10.450? [H3O+] = M h. What is the pOH of an aqueous solution of 0.121 M hydrochloric acid?
The Correct Answer and Explanation is :
Let’s break down the problems and address each one step by step.
1a. Formula for the Conjugate Base of H2SO3
- H2SO3 (sulfurous acid) dissociates as follows: H2SO3⇌H++HSO3−H_2SO_3 \rightleftharpoons H^+ + HSO_3^- The conjugate base of H2SO3 is the species that remains after it donates a proton (H+), which is HSO3-.
1b. Formula for the Conjugate Acid of H2PO4-
- H2PO4- (dihydrogen phosphate ion) can accept a proton (H+) to form its conjugate acid: H2PO4−+H+⇌H3PO4H_2PO_4^- + H^+ \rightleftharpoons H_3PO_4 Therefore, the conjugate acid of H2PO4- is H3PO4 (phosphoric acid).
2. Comparing the Weakest Acid
- Acid 1: HF (hydrofluoric acid), Acid 2: H2S (hydrosulfuric acid), and Acid 3: H2CO3 (carbonic acid):
- HF is a weak acid, with a pKa of 3.2.
- H2S is also weak, with a pKa of 7.0 for the first dissociation.
- H2CO3 is weak, with a pKa of 6.4 for the first dissociation.
- Weakest acid: H2S (because it has the highest pKa, indicating it’s less acidic).
3. Comparing Conjugate Bases of the Three Acids
- Acid 1: HOCl (hypochlorous acid), Acid 2: H3PO4 (phosphoric acid), and Acid 3: HF (hydrofluoric acid):
- The conjugate base of HOCl is OCl- (hypochlorite).
- The conjugate base of H3PO4 is H2PO4- (dihydrogen phosphate).
- The conjugate base of HF is F- (fluoride).
- Weakest conjugate base: F- because it comes from the weakest acid, HF.
4. Comparing the Conjugate Bases of These Three Acids
- Acid 1: HCN (hydrocyanic acid), Acid 2: H2CO3 (carbonic acid), and Acid 3: HSO3- (hydrogen sulfite):
- The conjugate base of HCN is CN- (cyanide).
- The conjugate base of H2CO3 is HCO3- (bicarbonate).
- The conjugate base of HSO3- is SO3^2- (sulfite).
- Strongest conjugate base: SO3^2- because it is from the strongest acid (HSO3-).
5. Hydronium Ion Concentration with pH = 3.730
- The pH is related to the concentration of hydronium ions (H3O+): pH=−log[H3O+]pH = -\log[H_3O^+] To find [H3O+], rearrange the equation: [H3O+]=10−pH[H_3O^+] = 10^{-pH} Substituting the given pH value: [H3O+]=10−3.730≈1.87×10−4 M[H_3O^+] = 10^{-3.730} \approx 1.87 \times 10^{-4} \, \text{M}
6. Hydronium Ion Concentration with pOH = 10.450
- pH and pOH are related by the equation: pH+pOH=14pH + pOH = 14 Therefore, the pH is: pH=14−10.450=3.550pH = 14 – 10.450 = 3.550 Now, find [H3O+]: [H3O+]=10−3.550≈2.82×10−4 M[H_3O^+] = 10^{-3.550} \approx 2.82 \times 10^{-4} \, \text{M}
7. pOH of 0.121 M Hydrochloric Acid
- Since HCl is a strong acid, it dissociates completely, so [H3O+] = 0.121 M.
- Use the relationship: pOH=14−pHpOH = 14 – pH First, calculate pH: pH=−log(0.121)≈0.920pH = -\log(0.121) \approx 0.920 Now, calculate the pOH: pOH=14−0.920=13.080pOH = 14 – 0.920 = 13.080
Conclusion
- Conjugate base of H2SO3: HSO3-.
- Conjugate acid of H2PO4-: H3PO4.
- Weakest acid: H2S.
- Weakest conjugate base: F-.
- Strongest conjugate base: SO3^2-.
- [H3O+] for pH 3.730: 1.87 × 10^-4 M.
- [H3O+] for pOH 10.450: 2.82 × 10^-4 M.
- pOH of 0.121 M HCl: 13.080.