Question

What Will Run Out First?

Learning Goal:

To identify the limiting reactant and use it to calculate the amount of product.

As you begin to work limiting reactant problems, let us first consider an example that you might encounter at home.

Imagine that it is lunch time and you need to make a total of four turkey sandwiches for you and your friends. The "formula" for making a turkey sandwich calls for two slices of bread, two slices of turkey, and one slice of cheese. To make the four sandwiches, you will need eight slices of bread, eight slices of turkey, and four slices of cheese.

When you go to the refrigerator and gather all of the ingredients, you discover that you only have seven slices of bread instead of the eight that you need. You have plenty of the rest of the ingredients. Since you don't have enough bread to make all four sandwiches, the bread is considered to be the limiting reactant. A limiting reactant will determine how much product, in this case the sandwich, you can make. It is the reactant, or ingredient, that is present in the smallest amount when you take into consideration the ratio of reactants. The rest of the ingredients are considered to be excess reactants, meaning you have more than is necessary. Based on the amount of ingredients you have and the "formula", you will be able to make three and one-half sandwiches. You will use all of the bread and will have leftover turkey and cheese.

Balance the chemical reaction equation

P4(s)+Cl2(g)→PCl5(g)

Enter the coefficients in order, separated by commas (e.g., 1,2,3).