Question

How many moles of Pb(NO3)2 are requiredif 12 moles of Al(NO3)3 are produced?3Pb(NO3)2 + 2AlCl3 + 3PbCl2 + 2A1(NO3)32-

Answer 1

Step 1 - Finding the stoichiometry of the reaction

The given reaction is:

`3Pb(NO_3)_2+2\text{AlCl}_3\to3\text{PbCl}_2+2Al(NO_3)_3`

The stoichiometry of the reaction can be found by the bigger numbers that come before the formula of the substances:

3 moles of Pb(NO3)2 react with 2 moles of AlCl3 thus producing 3 moles of PbCl2 and 2 moles of Al(NO3)3

Step 2 - Using the stoichiometry to solve the question

The stoichiometry of a reaction works like a cake recipe. It defines a fixed proportion between the reactants and the products. We can thus use it to predict how much moles of Pb(NO3)2 would be needed.

In step 1, we have stated that:

3 moles of Pb(NO3)2 produce 2 moles of Al(NO3)3

Now let's set the following proportion:

`\begin{gathered} 3\text{ moles of Pb(NO3)2 produce --- 2 moles of Al(NO3)3} \\ x\text{ moles ----------------- 12 moles of Al(NO3)3} \\ \\ x=(12*3)/(2)=18\text{ moles} \end{gathered}`

Therefore, 18 moles of Pb(NO3)2 would be required.