We recently did two labs where we were given the task of observing single-replacement and

double-replacement reactions. This paper has background information on the different types of

chemical reactions, as well as the chemistry behind the two reactions we observed in lab.

A chemical reaction is a process that is characterized by a chemical change in which the

reactants (starting products) are different from the products. Chemical reactions involve the

breaking of old bonds and the formation of new bonds. They can result in the formation of

precipitates, changes in color, production or absorption of heat, or formation of gas bubbles.

Chemical reactions can be placed in the following five categories: (i) synthesis (ii)

decomposition …show more content…
However, not all single-replacement reactions which appear to work on paper occur in real life.

This is seen with fluorine, chlorine, bromine, and iodine. These elements are called halogens and

are found in group VII of the periodic table. Only the halogens on top of the column will replace

halogens below. This is seen in this example where chlorine which is above iodine in the

periodic table replaces it in this single replacement reaction: KI(aq) + Cl2(g) → KCl2(aq) + I(s).

Here is an example of a reaction that will not occur: CaF2(s) + Br2(l) → CaBr2(s) + F2(g). In

this reaction bromine cannot replace fluorine because bromine is below fluorine on the periodic

table. Both fluorine and bromine, when reacting with an atom, gain an electron to form a

negative ion. Fluorine is better at forming a negative ion then bromine in the reaction because

fluorine is more electronegative than bromine (fluorine is the most electronegative element).

Fluorine does a better job of attracting an incoming electron and thus becoming ionized than

bromine because of the stronger pull of electrons to its nucleus. That is the reason why …show more content…
The reactivity of some of the metals, especially in the Group I and Group II

metals, to water, acids, and oxygen can also be predicted to a certain extent. So, the reactivity of

metals and their compounds follow defined trends. By investigating the reactions of metals with

water, acids, and oxygen, we can create a reactivity series.

Here is a reactivity series chart:

(Chemical Reactions PPTX4 Mrs.McNamara’s

PowerPoint Slide 30)

According to the Reactivity Series shown above, metals can be ranked in order of increasing

reactivity going down the group in the periodic table. Metals that are higher up in the series will

displace metals that are lower in the series. So, using this information, in the reaction below, we

can predict the displacement reaction: K + NaCl → KCl + Na. In this reaction, potassium

will displace sodium (because potassium is higher up in the Reactivity Series). A similar ranking

can be done with reactions of metals and acids. According to the Reactivity Series, potassium

reacts strongly with acids while copper reacts weakly with acids. The Reactivity Series also

shows that the Group I metals react strongly with oxygen while Transition Metals like silver