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26 August, 01:17

A solution containing sodium fluoride is mixed with one containing calcium nitrate to form a solution that is 0.015M in NaF and 0.010M I. Ca (NO3) 2. Calculate the reaction quotient (Q) for the possible cross product CaF2, and compare Q to the solubility product constant of CaF2 to determine if a percipitate will form.

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  1. 26 August, 02:29
    According to the reaction equation:

    CaF2 (s) ⇄ Ca2 + (aq) + 2F - (aq)

    So the Q expression will be = [Ca2+][F-]^2

    and we will neglect the [ CaF2] as it is solid

    so, by substitution:

    when we have [Ca2+] = 0.01

    and [F-] = 0.015

    Q = 0.01 * (0.015) ^2

    = 6.3 x 10^-2

    by comparing Q value which is 6.3 x 10^-2 and Ksp value which is 1.8 x 10^-5

    So, we can see that Q > Ksp

    -that means precipitation will form as ion concentration are greater than

    equilibrium concentration So, the reaction will proceed in reverse to achieve

    equilibrium. and the solution will be then supersaturated.
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