Access Millions of academic & study documents

Prelaboratory Periodic Table

Content type
User Generated
Subject
Chemistry
Type
Homework
Showing Page:
1/10
Name of student
Date that lab occurred
Title of the experiment: Two Groups on the Periodic Table
Purpose of the experiment
Evaluate the reactions of alkaline earth metal cations and the reactions between halogen and halide
to determine the identity of an unknown solution containing alkaline earth metal cations and
halides using periodic relationship.
Underlying theory of the experiment
Precipitation Reactions
One common type of reaction that occurs in aqueous solution is the precipitation reaction, which
results in the formation of an insoluble product, or precipitate. A precipitate is an insoluble solid
that separates from the solution. Group IIA, called the alkaline earths, comprises beryllium,
magnesium, calcium, strontium, barium and radium. These are moderately reactive metals. The
atoms of the alkaline earth elements lose two electrons to from cations with a charge of +2.
Compounds of the alkaline earth metal are ionic. Precipitation reactions usually involve ionic
compounds. For example, when an aqueous solution of Barium nitrate [Ba(NO
3
)
2
] is added to an
aqueous solution of potassium chromate (K
2
CrO
4
), a precipitate of Barium chromate (BaCrO
4
) is
formed:
Ba(NO
3
)
2 (aq)
+ K
2
CrO
4 (aq)
BaCrO
4 (s)
+ 2KNO
3(aq)
and potassium nitrate remains in solution. The preceding reaction is an example of a metathesis
reaction also called a double-displacement reaction, a reaction that involves the exchange of parts
between the two compounds. In this case, the cations in the two compounds exchange anions, so
Pb
2+
ends up with I
-
as PbI
2
and K
+
ends up with NO
3
-
as KNO
3
.
To predict whether a precipitate will form when a compound is added to a solution or when two
solutions are mixed, it depends on the solubility of the solute, which is defined as the maximum
amount of solute that will dissolve in a given quantity of solvent at a specific temperature.
Chemists refer to substances as soluble, slightly soluble, or insoluble in a qualitative sense. A
substance is said to be soluble if a fair amount of it visibly dissolves when added to water. If not,
the substance is described as slightly soluble or insoluble. All ionic compounds are strong
electrolytes, but they are not equally soluble. The table in the next page classifies a number of
common ionic compounds as soluble or insoluble.

Sign up to view the full document!

lock_open Sign Up
Showing Page:
2/10
Oxidizing Ability of Halogens
The halogens are located in Group VIIA on the periodic table. They are fluorine, chlorine, bromine,
iodine, and astatine. A distinction between the halogens and halides is that halogens are the free
elements such as Cl
2
, Br
2
and I
2
. Meanwhile, halides are combined forms, the anions, examples
are chloride ion (I
-
), bromide ion (Br
-
), and iodide ion (I
-
). In each case, a halogen higher in the
Group can oxidize the ions of one lower down. For example, chlorine can oxidize the bromide ions
to bromine:
Cl
2
+ 2Br
-
2Cl
-
+ Br
2
The bromine appears as an orange solution. As observe above, chlorine can also oxidize iodide
ions to iodine:
Cl
2
+ 2I
-
2Cl
-
+ I
2
The iodine appears either as a red solution if you are mean with the amount of chlorine you use,
or as a dark grey precipitate if the chlorine is in excess.
Bromine can only oxidize iodide ions to iodine. It isn't a strong enough oxidizing agent to convert
chloride ions into chlorine. A red solution of iodine is formed (see the note above) until the bromine
is in excess. Then you get a dark grey precipitate.
Br
2
+ 2I
-
2Br
-
+ I
2

Sign up to view the full document!

lock_open Sign Up
Showing Page:
3/10

Sign up to view the full document!

lock_open Sign Up
End of Preview - Want to read all 10 pages?
Access Now
Unformatted Attachment Preview
Name of student Date that lab occurred Title of the experiment: Two Groups on the Periodic Table Purpose of the experiment Evaluate the reactions of alkaline earth metal cations and the reactions between halogen and halide to determine the identity of an unknown solution containing alkaline earth metal cations and halides using periodic relationship. Underlying theory of the experiment Precipitation Reactions One common type of reaction that occurs in aqueous solution is the precipitation reaction, which results in the formation of an insoluble product, or precipitate. A precipitate is an insoluble solid that separates from the solution. Group IIA, called the alkaline earths, comprises beryllium, magnesium, calcium, strontium, barium and radium. These are moderately reactive metals. The atoms of the alkaline earth elements lose two electrons to from cations with a charge of +2. Compounds of the alkaline earth metal are ionic. Precipitation reactions usually involve ionic compounds. For example, when an aqueous solution of Barium nitrate [Ba(NO3)2] is added to an aqueous solution of potassium chromate (K2CrO4), a precipitate of Barium chromate (BaCrO4) is formed: Ba(NO3)2 (aq) + K2CrO4 (aq) → BaCrO4 (s) + 2KNO3(aq) and potassium nitrate remains in solution. The preceding reaction is an example of a metathesis reaction also called a double-displacement reaction, a reaction that involves the exchange of parts between the two compounds. In this case, the cations in the two co ...
Purchase document to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.
Studypool
4.7
Indeed
4.5
Sitejabber
4.4