Question

Which of the following equations is balanced?
H2+ O2arrowH2O

H2 + O2arrowH2O + O2

2H2 + O2arrow2H2O

4H2 + O2arrowH2O + O

Answer 1

Count the number of each type of atom showing on both sides. If the number of each atom is the same the equation is balanced.

Answer 2

So is it b?

Answer 3

In b you have two oxygen atoms on the left but three on the right, so it is not balanced.

Answer 4

thank you for helping me but i honestly don't have a clue what the answer is

Answer 5

okay look in first one its
H2 + O2 --> H2O
lets count how many H and O are on left and right side
there are 2 H atoms on the left side (H2)
there are 2 O atoms on the left side (O2)
now lets see right side
there are 2 H atoms and 1 O atom right?
the reaction is balanced ONLY when H atoms and O atom in the left side are equal to number of H and O atoms on the right side
as you see on the right side there is only 1 O atom while on the left side there are 2 atoms of O
that means this one is NOT balanced

Answer 6

now i'll take another example
the last reaction
4H2 + O2 ---> H2O + O
okay left side
no. of H atoms = 4*2= 8 [ 4 is coefficient of H atom and since we have H2 that means 2 H atoms so 4 will be multiplied by 2 atoms and we'll get 8 atoms ]
no. of O atoms = 2


now lets go to right side
H atoms = 2
O atoms = 2

now look, no. of H atoms on the left side is 8 while on right side its only 2

so this reaction is also not balanced :)
now try the other 2 reactions on your own
i hope you get it :D

Answer 7

The answer would be 2H2 + O2 arrow 2H2O. Because there is a coefficient in front of the H2, that indicates that there are two H2 molecules, meaning that there would be a total of 4 hydrogen atoms. There isn't a coefficient in front of the O2 so that means there is only two oxygen atoms. To balance the equation you need to make sure that you have the same number of "stuff" on the products side as there is on the reactants side. You have four hydrogen atoms and two oxygen atoms so you need to make sure that there is the same on the reactants side. The coefficient in front of the H2O means there is two H2 molecules and 2 O molecules. So you will have a total of four hydrogen atoms and two oxygen atoms.