{"id":32421,"date":"2025-06-22T13:37:40","date_gmt":"2025-06-22T13:37:40","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=32421"},"modified":"2025-06-22T13:37:41","modified_gmt":"2025-06-22T13:37:41","slug":"the-solubility-of-calcium-fluoride-caf2-in-pure-water-is-2-15-a-10-4-m","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/the-solubility-of-calcium-fluoride-caf2-in-pure-water-is-2-15-a-10-4-m\/","title":{"rendered":"The solubility of calcium fluoride, CaF2, in pure water is 2.15 \u00c3\u2014 10^-4 M."},"content":{"rendered":"\n

The solubility of calcium fluoride, CaF2, in pure water is 2.15 \u00c3\u2014 10^-4 M. What is the value of Ksp?<\/p>\n\n\n\n

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

To calculate the Ksp<\/strong> (solubility product constant) of calcium fluoride (CaF\u2082<\/strong>) from its solubility, we follow these steps:<\/p>\n\n\n\n

\n\n\n\n

Step 1: Write the dissociation equation<\/h3>\n\n\n\n

Calcium fluoride dissociates in water as follows:<\/p>\n\n\n\n

CaF\u2082 (s) \u21cc Ca\u00b2\u207a (aq) + 2 F\u207b (aq)<\/strong><\/p>\n\n\n\n

\n\n\n\n

Step 2: Define solubility<\/h3>\n\n\n\n

Let the solubility of CaF\u2082 be s = 2.15 \u00d7 10\u207b\u2074 M<\/strong>.
From the balanced equation:<\/p>\n\n\n\n

    \n
  • [Ca\u00b2\u207a] = s = 2.15 \u00d7 10\u207b\u2074 M<\/li>\n\n\n\n
  • [F\u207b] = 2s = 2 \u00d7 2.15 \u00d7 10\u207b\u2074 = 4.30 \u00d7 10\u207b\u2074 M<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    Step 3: Write the Ksp expression<\/h3>\n\n\n\n

    Ksp = [Ca\u00b2\u207a][F\u207b]\u00b2<\/strong><\/p>\n\n\n\n

    Substitute the concentrations:<\/p>\n\n\n\n

    Ksp = (2.15 \u00d7 10\u207b\u2074) \u00d7 (4.30 \u00d7 10\u207b\u2074)\u00b2<\/strong><\/p>\n\n\n\n

    First calculate (4.30 \u00d7 10\u207b\u2074)\u00b2:<\/p>\n\n\n\n

    (4.30 \u00d7 10\u207b\u2074)\u00b2 = 18.49 \u00d7 10\u207b\u2078 = 1.849 \u00d7 10\u207b\u2077<\/p>\n\n\n\n

    Then multiply:<\/p>\n\n\n\n

    Ksp = (2.15 \u00d7 10\u207b\u2074) \u00d7 (1.849 \u00d7 10\u207b\u2077)
    = 3.975 \u00d7 10\u207b\u00b9\u00b9<\/strong><\/p>\n\n\n\n

    \n\n\n\n

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

    Ksp = 3.98 \u00d7 10\u207b\u00b9\u00b9<\/strong><\/p>\n\n\n\n

    \n\n\n\n

    Explanation<\/h3>\n\n\n\n

    The solubility product constant (Ksp) represents the equilibrium constant for a solid dissolving into its ions in a saturated solution. In this case, calcium fluoride (CaF\u2082) dissolves in water to form calcium ions (Ca\u00b2\u207a) and fluoride ions (F\u207b). The Ksp expression is based on the concentrations of these ions raised to the power of their stoichiometric coefficients.<\/p>\n\n\n\n

    When 1 mole of CaF\u2082 dissolves, it yields 1 mole of Ca\u00b2\u207a and 2 moles of F\u207b. If the solubility (s) of CaF\u2082 is 2.15 \u00d7 10\u207b\u2074 M, this means the concentration of Ca\u00b2\u207a is also 2.15 \u00d7 10\u207b\u2074 M, while the concentration of F\u207b is twice that, or 4.30 \u00d7 10\u207b\u2074 M.<\/p>\n\n\n\n

    The Ksp is calculated using the equation:<\/p>\n\n\n\n

    Ksp = [Ca\u00b2\u207a][F\u207b]\u00b2<\/p>\n\n\n\n

    Substituting the concentrations derived from solubility gives:<\/p>\n\n\n\n

    Ksp = (2.15 \u00d7 10\u207b\u2074)(4.30 \u00d7 10\u207b\u2074)\u00b2<\/p>\n\n\n\n

    First, we square the fluoride ion concentration and then multiply by the calcium ion concentration. This gives a final Ksp value of approximately 3.98 \u00d7 10\u207b\u00b9\u00b9.<\/p>\n\n\n\n

    This calculation is important in chemistry for predicting whether a precipitate will form in a solution. A low Ksp value like this indicates that CaF\u2082 is not very soluble in water, which aligns with what is observed experimentally.<\/p>\n\n\n\n

    \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

    The solubility of calcium fluoride, CaF2, in pure water is 2.15 \u00c3\u2014 10^-4 M. What is the value of Ksp? The Correct Answer and Explanation is: To calculate the Ksp (solubility product constant) of calcium fluoride (CaF\u2082) from its solubility, we follow these steps: Step 1: Write the dissociation equation Calcium fluoride dissociates in water […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-32421","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=32421"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32421\/revisions"}],"predecessor-version":[{"id":32423,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32421\/revisions\/32423"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=32421"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=32421"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=32421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}