# Chemistry

posted by on .

Calcium reacts with nitrogen to form calcium nitride. Indicate which reactant is limiting, calculate the mass of calcium nitride formed when 50.0g of calcium reacts with 50.0g of Nitrogen. How much excess reactant do you have?

• Chemistry - ,

3Ca + N2 ==> Ca3N2
mols Ca = grams/atomic mass
mols N2 = grams/molar mass

Using the coefficients in the balanced equation, convert mols Ca to mols product.
Do the same for mols N2 to mols product.
It is likely that these two values for mols product will not agree which mans one of them is wrong. The correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that number is the limiting reagent.
g Ca3N2 = mols Ca3N2 x molar mass Ca3N2.

How much of the excess reagent is left?
Using the coefficients in the balanced equation (just as you did in converting to mols product), convert mols of the limiting reagent to mols of the non-limiting reagent. This tells you how much of that reagent was used. Subtract amount used from initial amount to find amount not reacted.
Post your work if you get stuck.

• Chemistry - ,

13