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August 21, 2014

August 21, 2014

Posted by **Sue** on Sunday, October 17, 2010 at 2:39pm.

- chemistry -
**DrBob222**, Sunday, October 17, 2010 at 3:10pmTwo equations in two unknowns; solve simultaneously.

Let X = mass CaCO3

Let Y = mass MgCO3

======================

X + Y = 7.85 grams.

X(moles mass CO2/molar mass CaCO3) + Y(molar mass CO2/molar mass MgCO3) = grams CO2. [Note: YOu will need to use PV = nRT to calculate moles CO2, then convert that to grams CO2.]

Solve for X and Y then apply

%CaCO3 = (mass CaCO3/mass sample)*100 = ??

%MgCO3 = (mass MgCO3/mass sample)*100 = ??

Post your work if you get stuck.

- chemistry -
**Sue**, Sunday, October 17, 2010 at 4:52pmThank you. But could you explain how you got that equation for solving for x and y? I need to prove my answer.

- chemistry -
**Sue**, Sunday, October 17, 2010 at 5:02pm.819 mol CO2= 30604 g CO2

X= 3.604 g CO2/100.09 g/molCaCO3= .036 mol CaCO3

Y=3.604 g CO2/84.32 g/mol MgCO3= .043 mol MgCO3

I'm stuck. I don't think I did it right.

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