Fundamental H5 D

[Michelle Shin 4B]

To balance Fe2P (s) + S(s) -> P4S10 (s) + FeS(s), how do you know which element to start balancing first?

[Tai Metzger 3K]

Generally, it is easiest to start with the element that appears only once on each side of the equation and then move on to the more complex elements. In this case, I recommend starting with Fe.

[MinuChoi]

You can save balancing S for last, since it appears several times on one half of the equation.
And since S is its own particle on the reactants side, balancing S will be really easy once the Fe and P are balanced out.

[Aadil Rehan 1D]

I usually start by looking for the minimum coefficient that something has to be multiplied by - for example, since there's 4 phosphorus atoms on the right side, I know that Fe₂P has to have a coefficient of at least 4. It can be reverse-solved from there, usually.