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Desperate.... - Unknown metal practical help! How to find RMM of metal X watch

1. I'm really really confused about my practical, you have to find the RMM of XCO3 and from that find out which metal X is and the answer is Magnesium but I have no idea how to get to that. I know you have to subtract the RAM of C and O3 from the mass of XCO3 but I can't even get the mass of XCO3.
Thanks!
Attached Files
2. FORMULA OF COMPOUND.wps.doc (12.5 KB, 84 views)
3. Anyone??
4. 15.7 - 12.7 = mass of XCO3
14.806 - 12.7 = mass of XO
15.7 - 14.806 = mass of CO2

(15.7 - 14.806)/3.00 x 100 = 29.8% mass of CO2 in XCO3 (0.0203 moles of CO2 given off)

This means you started with 0.0203 moles of XCO3 (and 0.0203 moles of XO)

Mr = mass/moles => 3.00/0.0203 = x + (12 + (16 x 3)) => x = 87 (i.e. Sr)

I'm sorry to say the problem is really with your results rather than your analysis
5. (Original post by EierVonSatan)
15.7 - 12.7 = mass of XCO3
14.806 - 12.7 = mass of XO
15.7 - 14.806 = mass of CO2

(15.7 - 14.806)/3.00 x 100 = 29.8% mass of CO2 in XCO3 (0.0203 moles of CO2 given off)

This means you started with 0.0203 moles of XCO3 (and 0.0203 moles of XO)

Mr = mass/moles => 3.00/0.0203 = x + (12 + (16 x 3)) => x = 87 (i.e. Sr)

I'm sorry to say the problem is really with your results rather than your analysis
Thank you so much! I got that when I first did it and I deleted it thinking it was wrong (which it is really)
The whole class got weird results lol but thank you!!!!
Rep is coming!

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