In the reaction h2 + n2 2 nh3, what coefficient should be placed in front of o2 to balance the reaction

In order to balance this equation you need to count each element and how many of the individual elements are in the equation. _H2+N2=2 NH3 You multiply the 2 (Which is the coefficient) by the 3 (which is the subscript) This would equal 6 which indicated there are 6 hydrogen atoms on the right side so the left side should also have 6 hydrogen atoms
The missing coefficient on the left side must multiple the 2 to become 6 hydrogen Answer=3
 

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