chemistry
posted by john .
for each of the following synthesis reaction indentify the missing reactant(s) or product(s) and then balance the resulting equation
a) Mg +__________ > MgO
b) _________ + O2> Fe2O3
c) Li + Cl2 > _________
d) Ca + __________> CaI2

Tell me what you don't understand about these problems. It appears obvious to me that the first one must have O2 added to it to obtain MgO.
Mg + O2 ==> MgO, then balance by
2Mg + O2 ==> 2MgO
The others are done the same way. 
so for B) would it be 2Fe2O3?
c) 1LiCl2
d) 2Cal2 
B is Fe + O2 ==> Fe2O3. then balance to give
4Fe + 3O2 ==> 2Fe2O3
C is Li + Cl2==> LiCl (the valence of Li is 1 and Cl is 1; therefore, the formula is LiCl. Then balance.
d. Ca + I2 ==> CaI2, then balance. 
so C is 1Li1Cl
d is Ca2l2? 
C is
Li + Cl2 ==> LiCl, then if you want to balance it it is
2Li + Cl2 ==> 2LiCl (Placing a 1, as in Li1Cl, is not wrong BUT no one does it BECAUSE if we write Li we imply there is one of Li; therefore, we don't write the 1s, only numbers that are not 1. )
I don't know where you get Ca2I2?
Ca + I2 ==> CaI2 and it is balanced as is.