So to balance an equation, you need to get the same amount of each type of element on either side of the --> . So you pretty much are given the subscripts in the equations and you need to add coefficients (just normal numbers) in front of any formula that needs it, keeping anything balance.

turns into

These coefficient numbers are the molar ratios, so 2 moles of KCl3 for every 3 moles of O2 so 1. 3:2
Then you can use these ratios of find out how many moles of one thing are needed if you are given the amount of another.

and use cross multiplication to solve for whatever you don't know
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Atoms must gain or lose electrons in order to become ions if they are to form ionic bonds.
Answer:
26.95 %
Explanation:
Air contains the highest percentage of oxygen and nitrogen gases. Magnesium then combines with both of the gases:


Firstly, find the total number of moles of magnesium metal:

Let's say that x mol react in the first reaction and y mol react in the second reaction. This means:

According to stoichiometry, we form:

Multiplying moles by the molar mass of each substance will yield mass. This means we form a total of:

The total mass is given, so we have our second equation to solve:

We have two unknowns and two equations, we may then solve:


Express y from the first equation:

Substitute into the second equation:





Moles of nitride formed:

Convert this to mass:

Find the percentage:
