Reactivity of Periodic Elements - Lab Report Example

• Introduction

This study involves a series of experimental procedures to investigate the reactivity of elements with one another. The principle of reactivity is that when a compound reacts with an element that is more reactive, the reactive element displaces the less reactive element from the compound, by either losing electrons or gaining more electrons. The reactivity is studied in relation to the group and the period of the elements. When the element in the compound is more reactive than the independent element, there is no reaction. For metallic elements, their reactivity reduces across the periodic table as one move from left to right (Briggs, 2005). The elements in the periodic table shift from metallic to metalloids, then to non-metallic elements. The metallic properties increase in the elements as we move from one period to the next one. For example, period three elements include sodium (metal),  silicon (metalloid)  chlorine (nonmetal).

Reactivity is the likelihood of an atom of an element reacting with other elements, depending on the ease with which electrons are removedusing the ionization energy and the affinity they have towards the electrons of other atoms (electronegativity). Essentially, chemical reaction involves the transfer of electrons and interaction between electrons of various elements. For metals, reactivity decreases from the left to the right across the period. In a group trend, reactivity increases down the group. In the periods, reactivity increases from the left to the right across the periods. In the groups, reactivity reduces as we move downwards in the group.

This study consists of two experiments for part 1 and part 2. Part 1 deals with the Relative Solubility of Alkaline Earth Compounds. Part 2 deals with the Metal Activity Series, specifically Metal Displacement Reactions. The trend of alkaline earths metals losing their two outermost electrons is exhibited in the reactivity of Magnesium towards halogens and oxygen.

• Objective of the Experiment

The objectives of the experiments are:

• To investigate the reactivity trend if the alkali earth metals
• To investigate the solubility of the compounds of alkali earth metals
• Part 1
  • Experimental Procedure

In this experiment, we begin by preparing two sets of solutions. The first set is a combination of solutions of nitrates of group 2 metals such as barium nitrate Ba (NO3)2, calcium nitrate Ca(NO3)2, magnesium nitrate Mg(NO3)2, and strontium nitrate Sr(No3)2. The second set is a combination of solutions of sulphates (SO42-), carbonate (CO32-), oxalate (C2O42-), and iodate (IO3-) of group 2 metals, which are polyatomic anions. The next step is to mix the solutions in the first set with the solutions in the second set, noting the possible changes that may indicate a chemical reaction such as persistent color changes and the appearance of precipitate, or production of gas bubbles. Table 1 below is used to record the mixture that had reaction take place.

In test 1, we test and observe the reaction between the Group 2 Nitrates and H2SO4.

In test 2, we test and observe the reaction between the Group 2 Nitrates and Na2CO3.

In test 3, we test and observe the reaction between the Group 2 Nitrates and (NH4)2C2O4.

In test 4, we test and observe the reaction between the Group 2 Nitrates and KIO3.

• • Results

Table 1: Relative Solubility of Alkali Earth Metal

Test Reagents

Group 2

Nitrates

H2SO4

Na2CO3

(NH4)2C2O4

KIO3

Ba (NO3)2

√

√

√

√

Ca(NO3)2

√

√

√

√

Mg(NO3)2

No Reaction

No Reaction

√

√

Sr(No3)2

No Reaction

√

√

√

Only three tests were found not to yield as shown below.

Mg (NO3)2 +H2SO4

Mg (NO3)2 +Na2CO3

Sr (No3)2 +H2SO4

• • Discussion and Analysis

The experiments that had reactions taking place were as ticked in table 1 above. The equations of reaction are as shown below.

Equations of the Reactions

H2SO4 + Ba (NO3)2  BaSO4 + 2HNO3

Na2CO3 + Ba (NO3)2  2 Na (NO3) + BaCO3

Ba (NO3)2(aq) + (NH4)2C2O4 (aq)  BaC2O4(s) + 2NH4NO3 (aq)

• Ba (NO3)2 + 2KIO3  Ba (IO3)2 + 2K (NO3)
• Ca (NO3)2 + H2SO4  CaSO4 + HNO3

Na2 CO3 + Ca (NO3)2  2 NaNO3 + CaCO3 (s)

(NH4)2C2O4 (aq) + Ca (NO3)2(aq) → CaC2O4(s) + 2 NH4NO3 (aq)

Ca (NO3)2 + 2KIO3  2KNO3 + Ca (IO3)2

Mg (NO3)2 + 2 KIO3  Mg (IO3)2 + 2 K (NO3)

Mg (NO3)2 + (NH4)2C2O4  MgC2O4(s) + 2 NH4NO3

KIO3 + Sr (NO3)2  Sr (IO3)2 + KNO3

Sr (NO3)2 (aq) + Na2CO3 (aq)  SrCO3 (s) + 2NaNO3 (aq)

From the observation, the set of alkaline earth ions and solution anions which showed precipitate. Predict the chemical formulas of the observed precipitates. There was a periodical recurrence trend of the relative solubility’s in Na2CO3, (NH4)2C2O4 and KIO3. There was no recurring trend with H2SO4 acid. The observable trend of solubility varied rather smoothly in the sets of alkaline earth elements. This is to mean, the reactivity decrease gradually down the group. By this observation on the trends of solubility, the order solubility was descending across the period.

In the solubility test:

Ba (NO3)2 was able to dissolve in H2SO4, Na2CO3, (NH4)2C2O4 and KIO3.

Ca (NO3)2 was able to dissolve in H2SO4, Na2CO3, (NH4)2C2O4 and KIO3.

Mg (NO3)2 only dissolved in (NH4)2C2O4 and KIO3.

Sr (No3)2 only dissolved in (NH4)2C2O4 and KIO3.

The right order of solubility among the group 2 nitrates in the list is shown below, in the descending order.

Ca (NO3)2  Mg (NO3)2Ba (NO3)2 Sr (No3)2

• Part 2
  • Experimental Procedure

In this experiment, we investigate the reactivity Series Metal in metals. We begin by the preparation of the six group 2 metals such as Calcium Ca, Copper Cu, Iron Fe, Magnesium Mg, strontium Sn, and Zinc Zn. In test 1, we add a small piece of each of the group 2 metals into separate test tubes having hydrochloric acid HCl. In test 2, we add a small piece of each of the group 2 metals into separate test tubes having Calcium Nitrate Ca(NO3)2. This is repeated with solutions of Cu (NO3)2, FeSO4, Fe (NO3)3, Mg (NO3)2, SnCl4 and Zn (NO3)2,while noting the presence or otherwise, absence of any evidence of reaction. In this regard, there is no test on the reaction between an element and a solution containing its own ions. Table 2 below shows the results of reactive series of Alkali Earth Metals.

During the reaction, we record the changes and any sign of reaction, such as the color change, production of gas.

• • Results

Table 2: Reactivity Series of Alkali Earth Metal

Solution

Metal

HCl

Ca (NO3)2

Cu (NO3)2

FeSO4

Fe (NO3)3

Mg (NO3)2

SnCl4

Zn (NO3)2

Ca

√

-

√

√

√

√

√

√

Cu

√

X

-

X

X

X

√

√

Fe

√

X

√

-

-

X

√

√

Mg

√

X

√

√

√

-

√

√

Sn

√

X

X

X

X

X

-

√

Zn

√

X

X

X

X

X

X

-

The results in table 1 above show the displacement of the less reactive elements from their aqueous solutions. The reactivity of the alkali earth metals Ca, Cu, Fe, Mg, Sn and Zn is shown to reduce down the group, even though they possess the same number of electrons in the outer energy levels. The boxes with √ show combinations that caused reaction. On the other hand, the boxes with X show combinations that had no chemical reaction.

• • Equations of Reaction

The equations of reaction in the group 2 elements (alkali earth metals) are shown below.

Calcium Ca

2 Ca + Cu (NO3)2  2 Ca (NO3) + Cu

Ca + FeSO4  CaSO4 + Fe

Ca + Fe (NO3) Ca (NO3)2 + Fe

2 Ca + Mg (NO3)2  Mg + 2 Ca (NO3)

Ca + SnCl4  CaCl + Sn

2 Ca + Zn (No3)2 2 Ca (No3) + Zn

Ca (s) + 2HCl (aq)  CaCl2 (aq) + H2 (g)

Copper Cu

Cu + SnCl4  CuCl4 + Sn

Cu(s) + Zn (NO3)2(s)  Cu (NO3)2(s) + Zn(s)

Cu (s) + 2HCl (aq)  CuCl2 (aq) + H2 (g)

Iron Fe

2 CuNO3 + Fe  Fe (NO3)2 + 2 Cu

Fe + SnCl4  FeCl4 + Sn

Fe + Zn (NO3)2  Fe (NO3)3 + Zn

Fe (s) + 2HCl (aq)  FeCl2 (aq) + H2 (g)

Magnesium Mg

2 Mg + Cu (No3)2  2 Mg (No3) + Cu

3 Mg + 3 FeSO4  3 MgSO4 + Fe3

4 Mg + SnCl4  4 MgCl + Sn

Mg (s) + Zn (NO3)2(aq) → Mg (NO3)2(aq) + Zn (s)

Mg (s) + 2HCl (aq)  MgCl2 (aq) + H2 (g)

Tin Sn

Sn + Zn (NO3)2  Sn (NO3)2 + Zn

Sn (s) + 2HCl (aq)  SnCl2 (aq) + H2 (g)

• • Discussion and Analysis

In the reactivity series, Ca was able to displace all the metallic ions such as Cu, Fe, Mg, Sn and Zn from their solutions. At the same time, it is evident that calcium was not displaced from its compounds, by any metal. In the same way, Mg was able to displace Cu in Cu (NO3)2, Fe in FeSO4, Fe in Fe (NO3)3, Sn in SnCl4 and Zn in Zn (NO3)2. Cu was able to displace Sn in SnCl4 and Zn in Zn (NO3)2. Fe was able to displace Cu in Cu (NO3)2, Sn in SnCl4 and Zn in Zn (NO3)2. Zn was not able to displace any ion of any other element, because it was the least reactive in the series. The right order of reactivity in the group 2 elements (alkali earth metals) is Ca Mg  Fe  Cu Sn  Zn, in descending order (Lim, 2005).

• Conclusion

The trend of reactivity of alkali earth metals reveals that reactivity decreases from the left to the right across the period, and reduces the group. From the two experiments, the common finding was that the elements high in the groups displace then elements in the lower group in the periodic table. The observation of the solubility varies rather smoothly in the set of alkaline earth elements. The trends of solubility confirm that the reactivity of the metals decrease as one moves down the group.