[sapphiregirl]

From the information below, determine the mass of substance C that will be formed if 45.0 grams of substance A reacts with 23.0 grams of substance B. (Assume that the reaction between A and B goes to completion.)
 
a.) Substance A is a gray solid that consists of an alkaline earth metal and carbon (37.5% by mass). It reacts with substance B to produce substances C and D. Forty million trillion formula units of A have a mass of 4.26 milligrams.
b.) 47.9 grams of substance B contains 5.36 grams of hydrogen and 42.5 grams of oxygen.
c.) When 10.0 grams of C is burned in excess oxygen, 33.8 grams of carbon dioxide and 6.92 grams of water aree produced. A mass spectrum of subbstance C shows a parent molecular ion with a mass-to-charge ratio of 26.
d.)Substance D is a hydroxide of the metal in substance A.
 
so for step A i assumed that that Carbon had a mass of 3/8 of the total meaning the total amu is 32, which leaves 20 amu for the metal. the only metal that fits this is Be.
 
then for step B H20 was really the only substance hydrogen and oxygen that fit these ratios:
 
2/18 = .1 and 5.36/47.9 = 1
likewise, 16/18 = .89 and 42.5/47.9 = .89
 
so now i have Be2C + H20 -> C + D
 
for step C i wrote out a whole stoich chart and when i solved it i got C2H2 or HC2H for substance C
here's my stoich chart:
 
Balanced Equation 2C2H2 + 502 -> 4CO2 + 2H20
Molar Ratio 2 5 4 2
Molar Mass 26 32 44 18
Grams 10.0 30.72 23.8 6.92
Moles .38 .96 .77 .38
 
also (2/18) = (x/6.92) yields .8 grams of Hydrogen meaning out of the water 6.12 grams are oxygen
and (16/18) = (x/33. yields 9.2 grams of Carbon meaning out of the carbon dioxide 24.6 grams are oxygen
6.12 plus 24.6 gives you 30.72 hence the 30.72 grams of oxygen in the chart
everything else was either given or solved from there
 
then for step d it says that substance d is the hydroxide of the metal in substance A so Be(OH)2
 
putting that all together gives you the equation
 
Be2C + H2O -> C2H2 + Be(OH)2
 
but i can't balance that equation

have I been doing the problem correctly? if so, how do you balance that final equation?

[nj_bartel]

http://www.chemicalforums.com/index.php?topic=28859.0;topicseen

[Borek]

alkaline earth metal and carbon (37.5% by mass)

Be2C + H2O -> C2H2 + Be(OH)2

Be₂C has 40.0% C.

Topic locked, feel free to continue in the old thread.