If 0.500 moles of silver nitrate were consumed, how many moles of calcium nitrate would be produced?(make sure to balance the chemical equation first)

Question

AgNO3 + CaCl2 → Ca(NO3)2 + AgCl

Please help me, I am very confused and this is due today!

Answer 1

First, balance the chemical reaction equation:

AgNO₃ + CaCl₂ → Ca(NO₃)₂ + AgCl

Notice that there are two "NO₃" molecules on the right side of the equation and only one on the left? So let's add a prefix on the left to make them match:

2AgNO₃ + CaCl₂ → Ca(NO₃)₂ + AgCl

But notice that now there are two "Ag" atoms on the left side of the equation and only one on the right. Let's add a prefix on the right to make them match:

2AgNO₃ + CaCl₂ → Ca(NO₃)₂ + 2AgCl

By doing that, you have also matched the chlorine atoms (now two on the left and two on the right). Everything now balances, two Ag atoms on both left and right; two NO₃ molecules on both left and right; one Ca atom on both left and right; and two Cl atoms on both left and right.

Now, instead of thinking about this as atoms and/or molecules, think of the chemical reaction equation in units of moles. They are in fact the same ratios. It says that 2 moles of AgNO₃ (silver nitrate) are required to produce 1 mole of Ca(NO₃)₂ (calcium nitrate). So if you only have half a mole (0.500 moles) of silver nitrate then it's clear to see that you could only produced a quarter of a mole (0.250 moles) of calcium nitrate.

The "math" way to do this is to multiply by the molar ratio like this: