2 Mg(s) + O2(g)  2 MgO(s)
206005
Exactly 3.5653g of MgO will be made. Ignore the other guys' answers; they're retards.
374337
Cl2 + 2 KI → I2 + 2 KCl
453465
Water vapor.\n2 H2 + O2 = 2 H2O
512544
2C18H18 + 45 O2 --->  36 CO2 + 18 H2O\n3Cu + 8HNO3 ----> 3Cu(NO3)2 + 2NO + 4H2O
531671
C3H8 + 5O2 --> 3CO2 + 4H2O
547667
BALANCED . . . \n\n2Sr + O2 ---> 2SrO\n\n. . . and solved . . .\n\nGet an "A".
375486
HClO2 + Ba(OH)2 -> BaClO2 + H2O\n\n2(NH4)3PO4 + 3Ca(NO3)2 -> 6(NH4)(NO3) + Ca3(PO4)2\n\nFinished and balanced.
288883
Cu(s) + 4HNO3 (aq)--> Cu(NO3)2(aq) + 2H2O(l) +2NO2(g)
474542
The method is very simple.  I can do the first and you can try the others.\n\n1.  First write the reaction and balance it.\n\n2HgO ---> 2Hg + O2.\n\n2. Convert grams to moles of whatever mass you have.  In this case you have O2 as 96 grams.  You convert to moles by dividing the mass by the molecular weight.  In this case, for O2 will be 32 g/mol\n\n96 grams / 32 g/mol = 3 mol.\n\n3. Now you look back to the equation.  In the equation for producing 1 mol O2 you need 2 moles of HgO.  If now have 3 moles O2, then you will need 2 x 3 moles of HgO, 6 moles.\n\n4. Now you need to convert the moles of HgO to grams.  To do this calculate the molecular weight of HgO.  It is 216.6 g/mol\n\n6 moles * 216.6 g/mol = 1299.6 g of HgO.
139991
decomposition reaction\n\n2H2O2 -------- O2   +  2H20
414375
I just added 2 everywhere:\n2KMnO4  K2O  2MnO O2\n\nThen took  care of Oxygen like this\n8=1+2+2x, x=5/2\n2KMnO4  == K2O 2MnO 5/2 O2\n\nThen made it whole number all.\n4 KMnO4  ==  2K2O  4MnO  5O2
422993
Na2C2O4\n Na +1, C +3, O -2
28854
the earlier equation is not balanced.\nCaO + 2HCl --------> CaCl2 + H2O
428206
C6 H12 O6 (arrow) 3CO2 + 6H2O
397846
CH4 + 2 O2 ---> CO2 + 2 H2O
368037
Na+ Cl-\nC +4 O-2 each\nK+ Br-\nN-3 H+1 each\nMg+2 O-2
54972
C6H12O6 +  O2 = CO2 + H2O + 38 ATP