Calculate mass percentage?!?

laracroftlaracroft
in Science & Mathematics

When heated @ 500degreesC, a 2.00g sample of limestone from a local quarry loses 0.273g. Calculate th mass percent of MgCO3 present in limstone.

MgCO3--> MgO + CO2

Calculate the mass loss on hearing 1.200g of a NaHCO3-NaCl mixture containing 65& NaCl.

Comments

  • anonymousanonymous

    Basic stoichiometry.

    The limestone lost CO2 in the reaction. (It can't lose MgO since magnesium oxide is a solid.)

    So, calculate the moles of CO2 produced.

    (0.273 g) / (44 g/mol) = 0.0062 mol CO2

    Look at the balanced equation. The moles of magnesium carbonate going in ought to be the same number as the moles of carbon dioxide produced. It's a 1 to 1 ratio.

    So...

    0.0062 mol CO2 = 0.0062 mol MgCO3

    (0.0062 mol) * (84.3 g/mol) = 0.52 g MgCO3

    (0.52 g MgCO3) / (2.00 g limestone) = 0.26

    Limestone is 26% magnesium carbonate.

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