Determine [H_3O^+], [OH^-] and the pH of 1.3 times 10^-6 M NaOH. Is this solutio
ID: 993638 • Letter: D
Question
Determine [H_3O^+], [OH^-] and the pH of 1.3 times 10^-6 M NaOH. Is this solution acidic, basic or neutral? A 0.1 M NaHCO_3 solution has a pH of 8.4. What is the [H_3)^+] and the [OH^-]? Is this solution acidic, basic or neutral? Select the stronger acid for the following jpair (determine which one has more product): Benzoic acid (K_a = 6.5 times 10^-5) or lactic acid (K_a = 8.4 times 10^-4) Answer True of False for the following statements:___The pH of 0.1 M HCl is higher than the pH of 0.1 M acetic acid (check in your book for weak/strong acids).___When you have a strong acid, you have a high concentration of that acid. A pH buffer is made by mixing together 11.1 g of sodium lactate (NaC_3H_5O_3) and 10.2g of lactic acid (HC_3H_5)_3) in 1.2 L. For lactic acid K_a = 1.4 times 10^-4. What is the pH of the buffer solution? How can you change the pH of a buffer?Explanation / Answer
4a.Concentration of NaOH = 1.3 x 10-6
The mole ratio between hydroxide ions and NaOH is 1:1
Hence,
[OH-] = Concn of NaOH = 1.3 x 10-6
pOH = - log [OH-]
pOH = - log 1.3 x 10-6 = 5.886
pH = 14 – pOH = 14 – 5.886 = 8.113
pH = - log [H-]
Therefore [H-] = antilog –pH
[H-] = antilog – 8.113 = 7.70 X 10-9
Thus, [OH-] = 1.3 x 10-6
[H-] = 7.70 X 10-9
pH = 8.113
4b. As the pH exceeds 7, the solution is basic.
5a. pH of NaHCO3 = 8.4
pH = - log [H-]
Therefore [H-] = antilog –pH
[H-] = antilog – 8.4 = 3.98 X 10-9
pOH = 14 – pH = 14 – 8.4 = 5.6
pOH = - log [OH-]
Therefore [OH-] = antilog –pOH
[H-] = antilog – 5.6 = 2.51 X 10-6
Thus, [OH-] = 2.5 x 10-6
[H-] = 3.98 X 10-9
5b. As pH exceeds 7, the solution is basic.
6. The strength of acid is determined by pKa.
Higher the value of pKa , stronger is the acid.
pKa for benzoic acid = - log (6.5 x 10-5) = 4.18
pKa for lactic acid = - log (8.4 x 10-4) = 3.07
As, pKa for benzoic acid is higher, benzoic acid is stronger as compared to lactic acid and benzoic acid will yield more product.
7a. False.(The concentration of hydrogen ions in case of HCl is higher than acetic acid and hence the pH of HCl is lower than that of acetic acid)
7b. False. (The strength of acid and concentration are not inter-related)
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