Question

Based upon the following equation: 3 Mg + N2 --> Mg3N2 How many moles of N2 are needed to react with 0.75 moles of Mg? *

a) 0.25
b) 2.25
c) 0.75
d) 0.375

Answer 1

This is a super duper simple moles to moles conversion! :)

Lets start with our given That is the 0.75 moles of magnesium. This always goes over 1.

0.75mol Mg
----------------
1

Then, we need to cancel out the moles of Mg to get to moles of Nitrogen. So, Moles of Mg would go on the bottom of the second step. Our BCE tells us we have 3 moles of it. Our BCE tells us we have 1 mole of N2. So our second step would look like this:

1mol N2
-----------
3mol Mg

When we put it together, it looks like this:

0.75mol Mg 1mol N2
---------------- x ---------------
1 3mol Mg

To get our answer, we can multiply all of the top numbers together, which gives us 0.75

Then, we can multiply all of our bottom numbers togther, which gives us 3

Then, we can divide our top answer by our bottom answer.

0.75/3 equals 0.25.

So, from 0.75 moles of magnesium, 0.25 moles of Nitrogen are produced.

So A would be your answer!!
Feel free to ask any more questions you may have.