A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass was red

Question

A 15.67 g sample of a hydrate of magnesium carbonate was heated, without decomposing the carbonate, to drive off the water. The mass was reduced to 7.58 g. What is the name of the hydrate

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Bơ 5 years 2021-07-28T23:13:25+00:00 1 Answers 1232 views 1

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  1. Giakhanh
    2
    2021-07-28T23:14:43+00:00
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    Answer:

    The correct answer is MgCO₃.5H₂O.

    Explanation:

    Based on the given information,

    The mass of hydrate of magnesium carbonate given is 15.67 grams, and the mass of anhydrous magnesium carbonate given is 7.58 grams.

    Now the mass of water will be,

    = 15.67 grams – 7.58 grams

    = 8.09 grams

    The molecular mass of magnesium carbonate is 84.32 grams, the moles of MgCO₃ can be determined by using the formula,

    Number of moles = Mass/Molecular mass

    Moles of MgCO₃ = 7.58/84.32

    = 0.0898 moles

    Similarly, the number of moles of water will be,

    Moles of H₂O = 8.099/18.02

    = 0.4489 moles

    After getting the values, there is a need to choose the smaller value and use it to divide both the values to get the ratio,

    MgCO₃ = 0.0898/0.0898 = 1

    H₂O = 0.4489/0.0898 = 4.9 or 5

    Thus, the molecular formula for the hydrate will be MgCO₃.5H₂O.

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