{"id":162499,"date":"2024-11-06T19:14:41","date_gmt":"2024-11-06T19:14:41","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=162499"},"modified":"2024-11-06T19:14:46","modified_gmt":"2024-11-06T19:14:46","slug":"what-is-the-ph-of-0-10-m-nafaq-the-ka-of-hf-is-6-8-x-10-4","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2024\/11\/06\/what-is-the-ph-of-0-10-m-nafaq-the-ka-of-hf-is-6-8-x-10-4\/","title":{"rendered":"What is the pH of 0.10 M NaF(aq). The Ka of HF is 6.8 x 10-4"},"content":{"rendered":"\n

What is the pH of 0.10 M NaF(aq). The Ka of HF is 6.8 x 10-4
A. 2.08
B. 8.08
C. 5.92
D. 14.92<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

The pH of a 0.10 M NaF solution can be determined by considering the behavior of NaF in water. Sodium fluoride (NaF) dissociates completely into Na\u207a and F\u207b ions. The fluoride ion (F\u207b) is the conjugate base of hydrofluoric acid (HF). To calculate the pH, we need to determine the concentration of OH\u207b ions in the solution due to the hydrolysis of F\u207b.<\/p>\n\n\n\n

Step 1: Write the hydrolysis reaction for F\u207b<\/h3>\n\n\n\n

The fluoride ion (F\u207b) reacts with water in the following equilibrium reaction:
[
F\u207b(aq) + H_2O(l) \\rightleftharpoons HF(aq) + OH\u207b(aq)
]
The fluoride ion accepts a proton (H\u207a) from water to form HF and releases hydroxide ions (OH\u207b), which makes the solution basic.<\/p>\n\n\n\n

Step 2: Set up an expression for the equilibrium constant (Kb)<\/h3>\n\n\n\n

To calculate the pH, we first need to calculate the base dissociation constant (Kb) for F\u207b. We can use the relation between Ka and Kb for conjugate acid-base pairs:
[
K_b = \\frac{K_w}{K_a}
]
where (K_w) is the ion product of water, (1.0 \\times 10^{-14}), and (K_a) is the acid dissociation constant for HF, which is given as (6.8 \\times 10^{-4}).<\/p>\n\n\n\n

[
K_b = \\frac{1.0 \\times 10^{-14}}{6.8 \\times 10^{-4}} = 1.47 \\times 10^{-11}
]<\/p>\n\n\n\n

Step 3: Set up the ICE table and solve for [OH\u207b]<\/h3>\n\n\n\n

Using the initial concentration of F\u207b, which is 0.10 M, we can set up an ICE (Initial, Change, Equilibrium) table for the hydrolysis reaction:<\/p>\n\n\n\n

Species<\/th>Initial concentration<\/th>Change in concentration<\/th>Equilibrium concentration<\/th><\/tr><\/thead>
F\u207b<\/td>0.10 M<\/td>-x<\/td>0.10 – x<\/td><\/tr>
HF<\/td>0<\/td>+x<\/td>x<\/td><\/tr>
OH\u207b<\/td>0<\/td>+x<\/td>x<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Using the expression for Kb:
[
K_b = \\frac{[HF][OH\u207b]}{[F\u207b]} = \\frac{x^2}{0.10 – x}
]
Since (K_b) is very small, we can assume that (x) is much smaller than 0.10 M, so (0.10 – x \\approx 0.10). Thus, the equation simplifies to:
[
1.47 \\times 10^{-11} = \\frac{x^2}{0.10}
]
Solving for (x):
[
x^2 = (1.47 \\times 10^{-11}) \\times 0.10 = 1.47 \\times 10^{-12}
]
[
x = \\sqrt{1.47 \\times 10^{-12}} = 1.21 \\times 10^{-6} \\text{ M}
]
This is the concentration of OH\u207b.<\/p>\n\n\n\n

Step 4: Calculate the pOH and pH<\/h3>\n\n\n\n

The pOH is related to the concentration of OH\u207b:
[
pOH = -\\log[OH\u207b] = -\\log(1.21 \\times 10^{-6}) = 5.92
]
Finally, the pH is calculated using the relation:
[
pH = 14 – pOH = 14 – 5.92 = 8.08
]<\/p>\n\n\n\n

Final Answer:<\/h3>\n\n\n\n

The pH of the 0.10 M NaF solution is 8.08<\/strong>.<\/p>\n\n\n\n

Thus, the correct answer is B. 8.08<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"

What is the pH of 0.10 M NaF(aq). The Ka of HF is 6.8 x 10-4A. 2.08B. 8.08C. 5.92D. 14.92 The Correct Answer and Explanation is: The pH of a 0.10 M NaF solution can be determined by considering the behavior of NaF in water. Sodium fluoride (NaF) dissociates completely into Na\u207a and F\u207b ions. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-162499","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/162499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=162499"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/162499\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=162499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=162499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=162499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}