F24

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AnvitaaAnandkumar_1B
Posts: 56
Joined: Fri Aug 02, 2019 12:15 am

F24

Postby AnvitaaAnandkumar_1B » Thu Oct 03, 2019 6:35 pm

Dolomite is a mixed carbonate of calcium and magnesium. Calcium and magnesium carbonates both decompose upon heat- ing to produce the metal oxides (MgO and CaO) and carbon dioxide (CO2). If 5.12 g of residue consisting of MgO and CaO remains when 10.04 g of dolomite is heated until decomposition is complete, what percentage by mass of the original sample was MgCO3?

Kevin Liu 1J
Posts: 53
Joined: Thu Jul 25, 2019 12:16 am

Re: F24

Postby Kevin Liu 1J » Thu Oct 03, 2019 9:39 pm

I would balance the equation first: Ca Mg(Co3)2 --> MgO + CaO + 2 CO2

Then find the amount of moles of CO2 using the mass (10.04 g - 5.12 g = 4.92 g). Use the moles of CO2 to calculate the moles of MgCO3. Finally, use the moles of MgCO3 to calculate the mass of MgCO3 that remains after the decomposition is complete.

To find the percentage, just divide the final mass over the original mass to get the percentage by mass.


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