when you have an equation and you are doing moles.. do you add the number infront of the compund(balancing) for the rmm

Question

i just got confused when you are doing a calculation and there is the balancing do you multiply the coumpound ram by the number?

Answer 1

It depends on what question you are trying to answer.  The rmm (relative molecular mass/molar mass/molecular weight) is the mass it takes to obtain 1 mole.  In the balanced equation, the coefficient (the number in front) indicates the number of moles needed.  Thus, if you want to know the mass, then YES, you do multiply by the coefficient.

Example:

3H₂ + N₂ ==> 2NH₃

It takes 3 moles of H₂ to react with 1 mole of N₂ to make 2 moles of NH₃.

rmm H₂ is 2;  N₂ is 28 and NH₃ is 17

So, it would take 6 g H₂ + 28 g N₂ to make 34 g NH₃ (or any multiple of these values). Note the conservation of mass.