Computing mass of CaF₂

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Dhamnekar Winod
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Computing mass of CaF₂

Post by Dhamnekar Winod »

Calculate the mass of CaF2 produced when 5g of Ca(NO3)2 is mixed with 3g of NaF in water, with a final volume of 500 mL. Ksp is 3.5E-11 for the system.

My attempt to answer: Reaction equation is Ca(NO3)2 + 2NaF → CaF2 + 2NaNO3, we have 3.047e-2 moles of Calcium Nitrate and 7.145e-2 moles of Sodium Fluoride
How to proceed further?
Last edited by Dhamnekar Winod on Mon Jul 05, 2021 10:16 am, edited 1 time in total.
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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ChenBeier
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Re: Computing mass of CaF2

Post by ChenBeier »

Check what is limiting agent.
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Dhamnekar Winod
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Re: Computing mass of CaF₂

Post by Dhamnekar Winod »

Mass of the CaF2 is 0.0304718 moles × 78.1 g(molar mass of CaF2 = 2.38 g.

I computed the solubility of CaF2 Calcium Fluoride in grams per liter in water from the Kₛₚ 3.5e-11 = 1.6 × 10⁻² g CaF2/L.

Molar solubility of CaF2 in 0.07145 M of NaF solution is 4.89E-10 M.

Are the above answers correct?
How to proceed further?
Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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ChenBeier
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Re: Computing mass of CaF₂

Post by ChenBeier »

I think the amount is driven from the limiting agent. Ca 2+ is limited ion. Everything what is above the soloubilty will precipitate. Its about 2.38 g.
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