7.8 - Single Replacement Reactions

Brianna L., Skylar K., Kristen H.

What are Single replacement reactions?

When replacing a possession, it’s often for a better model or for something else. Normally, these objects are being replaced by something similar, but better. In Chemistry, it works the same way. The difference is that possessions that are replaced turn into elements being replaced by other elements. This is how single replacement reactions work.

What are single replacement reactions? (cont.) Single replacement reactions occur when atoms of an

element switch places with another element in a compound. It can be followed like this:

Metal replacing metal/Nonmetal replacing nonmetal:

Requirements for a single replacement reaction to happen

Only elements can replace another if the element taking the place is MORE REACTIVE than the element being replaced.

* Metals above Hydrogen will replace it in acids.Metals above Sodium will replace Hydrogen in both acids and water.

Completing a single replacement reaction

Step 1. Determine if the reaction will occur In this instance, you would need to check the reactivity table to see if Zinc

can replace Hydrogen. According to the table, Zinc can replace Hydrogen.

Example: Zn + HCl

Step 2. Determine the productsSince Zinc replaces Hydrogen, it would leave the Hydrogen by itself,

resulting in H2.Zinc and Chlorine would form an ionic compound.

Step 3. Balance the equationH2 is already handled, however ZnCl is unbalanced. Zn has a +2 charge while Cl has -1. Add a subscript of 2 to Cl to balance the

compound to make the charges neutralAnswer: ZnCl 2+ H2

Question Time If a single replacement reaction happens in Zn + 2 HCl, what will the products be?

A. No reactionB. 2 Zn + H2C. ZnCl2 + H

2D. 2 ZnH + Cl2

Replacing nonmetals Single replacement reactions are not limited to just metals. This can

also occur with nonmetals. However, replacement of nonmetals is usually limited to the halogens of the periodic table.

The activity of the halogens decreases as it goes down the periodic table

Question Time Again Br22 + FeF3 will have which of these products?

D. No reaction

A. Br2Fe + F2

B. Br2 + FeCl3C. Br2Cl3 + Fe

Here’s your homework Reference the activity table, determining whether

or not a single replacement reaction occurs. If there is none, write “no reaction.” If there is a reaction, complete and balance the equation

1. Cl22 + NaF 2. NaI + Br2 3. Fe + HCl

4. Al + CuCl2