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 products Since Zinc replaces Hydrogen, it would leave the Hydrogen by itself, resulting in H 2. Zinc and Chlorine would form an ionic compound. Step 3. Balance the equation H2 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 neutral Answer: ZnCl 2 + H 2

Question Time  If a single replacement reaction happens in  Zn + 2 HCl, what will the products be? A. No reaction B. 2 Zn + H 2 C. ZnCl 2 + H 2 D. 2 ZnH + Cl 2

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  Br FeF 3 will have which of these products? D. No reaction A. Br 2 Fe + F 2 B. Br 2 + FeCl 3 C. Br 2 Cl 3 + 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. Cl 22 + NaF  2. NaI + Br 2  3. Fe + HCl  4. Al + CuCl 2