Reactivity of Halides
Reactivity of Halogens
Introduction:
During the first reactivity of metals lab, you learned that reactivity increases as you move down Group I of the periodic table. In the second lab, you generalized this observation to include Group 2 metals and you learned that reactivity decreases as you move from left to right on the periodic table. In addition, you used your observations of reactivity and atomic size to figure out that metals that hold onto their electrons with less force are more reactive, leading you to the conclusion that metals must be losing electrons during a chemical reaction.
Today you will be designing an investigation to determine the trend in reactivity for the halogens (Group 7 elements). To do this you will be observing a single replacement reaction. A single replacement reaction is one where an element replaces a different element in a compound. For example, the general formula for a single replacement reaction is:
A
BC
AC
B
Notice that element A replaced B in the compound. An example of a single replacement reaction is the possible reaction between the element aluminum and the compound copper(II) chloride.
2Al
(s)
3CuCl
2
(aq)
t
3Cu
(s)
2AlCl
3
(aq)
This reaction will only take place if the aluminum (the lone element) is more reactive than the copper (the element it is trying to replace). If the copper is more reactive than the aluminum, it will hold onto the chlorine and no reaction will take place. The nice thing about this reaction is that copper(II)
chloride solution is a light blue color and aluminum chloride is a clear
solution. If the reaction takes place the blue will color will disappear. If cooper is more reactive the solution will remain blue.
Pre Lab Questions:
1.
What is the purpose of today’s lab activity?
2.
Make a prediction about the reactivity of Group 7 elements as you move down the periodic table. Be sure to explain your reasoning.
Reactivity of Halogens
Introduction:
During the first reactivity of metals lab, you learned that reactivity increases as you move down Group I of the periodic table. In the second lab, you generalized this observation to include Group 2 metals and you learned that reactivity decreases as you move from left to right on the periodic table. In addition, you used your observations of reactivity and atomic size to figure out that metals that hold onto their electrons with less force are more reactive, leading you to the conclusion that metals must be losing electrons during a chemical reaction.
Today you will be designing an investigation to determine the trend in reactivity for the halogens (Group 7 elements). To do this you will be observing a single replacement reaction. A single replacement reaction is one where an element replaces a different element in a compound. For example, the general formula for a single replacement reaction is:
A
BC
AC
B
Notice that element A replaced B in the compound. An example of a single replacement reaction is the possible reaction between the element aluminum and the compound copper(II) chloride.
2Al
(s)
3CuCl
2
(aq)
t
3Cu
(s)
2AlCl
3
(aq)
This reaction will only take place if the aluminum (the lone element) is more reactive than the copper (the element it is trying to replace). If the copper is more reactive than the aluminum, it will hold onto the chlorine and no reaction will take place. The nice thing about this reaction is that copper(II)
chloride solution is a light blue color and aluminum chloride is a clear
solution. If the reaction takes place the blue will color will disappear. If cooper is more reactive the solution will remain blue.
Pre Lab Questions:
1.
What is the purpose of today’s lab activity?
2.
Make a prediction about the reactivity of Group 7 elements as you move down the periodic table. Be sure to explain your reasoning.
3.
Watch the reaction demonstration of Al and CuCl
2
. Record your observations in the table below.
Pre-Reaction Observations Post Reaction Observations
4.
What element are copper and aluminum atoms fighting over? a.
Should the element that ends up with the chlorine be considered more or less reactive? Explain your reasoning.
5.
Which is more reactive, aluminum or copper? How do you know this?
(Discuss two pieces of evidence from your observations) a.
What is the reddish-brown solid in the beaker? How do you know this? b.
If copper was more reactive, what would have happened when the aluminum was dropped into the copper(II) chloride solution. Explain your reasoning.
3.
Watch the reaction demonstration of Al and CuCl
2
. Record your observations in the table below.
Pre-Reaction Observations Post Reaction Observations
4.
What element are copper and aluminum atoms fighting over? a.
Should the element that ends up with the chlorine be considered more or less reactive? Explain your reasoning.
5.
Which is more reactive, aluminum or copper? How do you know this?
(Discuss two pieces of evidence from your observations) a.
What is the reddish-brown solid in the beaker? How do you know this? b.
If copper was more reactive, what would have happened when the aluminum was dropped into the copper(II) chloride solution. Explain your reasoning.
