Question #4cdbc

Jun 12, 2016

There are indeed 7 oxygen atoms in this equation.

Explanation:

I edited your question to make it more understandable. Maybe now you can see that there are indeed 7 oxygen atoms?

Lets first see how much of each element is in $2 C {O}_{2}$ :
you should read this as: $2 \cdot \left(C + {O}_{2}\right)$
which is similar to: $2 \cdot C + 2 \cdot \left(O + O\right)$
so there are $2$ carbon atoms ($C$) and $2 \cdot 2 = 4$ oxygen ($O$) atoms.

Than the elements in the second part $3 {H}_{2} O$ :
this you should read as: $3 \cdot \left({H}_{2} + O\right)$
which is similar to: $3 \cdot \left(H + H\right) + 3 \cdot O$
so there are $6$ hydrogen ($H$) atoms and $3$ oxygen ($O$) atoms

In total: $4 \cdot O$ in $2 C {O}_{2}$ and $3 \cdot O$ in $3 {H}_{2} O$ = $7$ oxygen atoms

Jun 12, 2016

There are seven Oxygen atoms in the reaction.

Explanation:

The numbers in front of the chemical formula indicate how many lots of that compund you have. The numbers apply to each element in the compound.

The example states:
$2 C {O}_{2} + 3 {H}_{2} O$

If the numbers apply to each element, and there is a small subscript number next to it, then you multiply them together.

For example, $2 C {O}_{2}$. Here there are 2 carbon atoms, as there is no number, which means that you only have one, and since there are 2 lots of $C {O}_{2}$, then you will have 2 carbon atoms and 4 oxygen atoms.

If we then apply this to the water molecules, we find that there are a total of 2 carbon atoms, 7 oxygen atoms, and 6 hydrogen atoms.