Chemistry AQA GCSE Relative Formula Mass Calculations

For example, there is the equation: 6 CO2+6 H2O → 1 C6H12O6 + 6 O2
In some situations, to find the Mr of O2, you'd just do 16 x 2. In other situations, like moles calculations, you might use the Mr of 6 x (16 x 2) for oxygen. What I'd like to know is when to use the balanced aspect of the equation and when not to, if possible!!

For example, there is the equation: 6 CO2+6 H2O → 1 C6H12O6 + 6 O2
In some situations, to find the Mr of O2, you'd just do 16 x 2. In other situations, like moles calculations, you might use the Mr of 6 x (16 x 2) for oxygen. What I'd like to know is when to use the balanced aspect of the equation and when not to, if possible!!

I remember there was one situation where you do use the big numbers as multipliers, maybe for atom economy or something similar to that. However, I would not rely on my memory at all.

Hopefully I can explain it in a way that makes sense - the Mr of O2 is constant it’s always 32. When there’s a 6 in front, it is describing the ratio of oxygen produced in the equation, so for every mole of glucose produced, six moles of O2 are produced. Using the 6 should only be used once you’ve calculated moles of something at least, never 6 X Mr. For example, if you’re trying to find the mass of O2 produced from the moles of CO2 added (let’s say there’s an excess of H2O), if you have 6 moles of CO2 to react, as it’s in a 6:6 (1:1) ratio, 6 moles of oxygen are going to be produced. To find the mass of oxygen, you would then multiply the number of moles made 6, by the mr of oxygen which is 32 (it’s the AR multiplied by their subscripts) making the mass of oxygen produced 192g. The large letters in front of any molecule in an equation act purely as a ratio between the different substances in the equation. Hopefully this helps!