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Stoichiometry - Mg & Zn(NO3)2?

I've looked this over and my answer just doesn't seem right...

Here is my chemical equation:

Zn(NO3)2 (aq) + Mg (s) → Mg(NO3)2 (aq) + Zn (s)

I want to know how many mL of zinc nitrate I will need to react completely with 4g of magnesium. I keep getting around 820mL - but that seems way farfetched for a mere 4g! Any help would be appreciated. Please show your process if you can. Here is my presumably incorrect calculation:

(4.0g Mg)/1 ∙ (1 mol Mg)/(24.31g Mg) ∙ (1 mol Zn (NO3)2)/(1 mol Mg) ∙ (1 L)/(0.20 mol Zn(NO3)2 ) ∙ (1000 mL)/(1 L) ≈ 820 mL Zn(NO3)2

Thanks a lot!

1 Answer

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  • 1 decade ago
    Favorite Answer

    Your answer is correct.

    No. moles of Mg = 4/24.3 = 0.165 mol = No. moles of Zn(NO3)2 required

    Assuming the concentration of Zn(NO3)2 is 0.20M

    Volume = 0.165/0.20 = 822 mL

    It does make sense if you think about it. Magnesium is a relatively light metal and so 4g of Magnesium actually contains quite a lot of Mg atoms. Furthermore, you are using a rather dilute solution of Zn(NO3)2, and so you should need a large amount of solution.

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