February 27, 2017

Homework Help: Chemistry. Please help!

Posted by Jordan on Wednesday, December 3, 2008 at 5:58pm.

A 20.29 g sample of impure MgCO3 is completely decomposed at 1000oC in previously evacuated 2.0 L reaction vessel. After the reaction was complete the solid residue had a mass of 15.9 g. Assume that only MgCO3 could produce gas CO2 what percent of original sample was magnesium carbonate? What was the pressure of the CO2 produced?

Ok, so everyone I have talked to has different ideas on how I should answer this question.

For part (A) the ideas have been.

(1) 15.9/20.29= 78.36%
(2) (20.29 - 15.9)/20.29 = 21.64%
(3) Use g of CO2 to find g of MgNO3. 4.39 g CO2 * (1 mol/44g) * (1 mol/1 mol) * (84g / 1 mol) = 8.38g
Then, 8.38/20.29 = 41.3%

Do any of those seem right? I also have ideas for part b, but I will write them later.

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