In the photosynthesis equation: 6COX2+6HX2Osunlight→CX6HX12OX6+6OX2, the only place where we have 6 molecules of OX2 is in 6COX2. Then it reacts with 6HX2O to form CX6HX12OX6 and 6OX2 that apparently comes from COX2. So why do we say that the OX2 produced by plants comes from HX2O and not COX2? Is it the photosynthesis formula which is wrong?