Report: Class and element identification
Title : Class and element identification
Day,
date : Monday, February 13, 2017
Purpose :
1. Assess the
similarity of the properties of the elements in the table.
2. Observe flame test and reaction of some alkaline and alkaline earth elements.
2. Observe flame test and reaction of some alkaline and alkaline earth elements.
Theoretical
basis :
Element of group one, alkali metal is relatively
abundant. Some of its compounds have been known
and exploited since prehistoric times. However, these
elements remained unspoken about two hundred years ago. Alkali metal compounds
are difficult to decompose by the usual chemical means, so the discovery of
these elements must wait for new scientific development. Sodium (1807) and
Potassium (1807) were discovered by electrolysis. Cesium (1860) and Rubidium
(1861) were identified as new elements through the emission spectrum. Fransium
(1939) was isolated from the radioactive decay product of Aktinium.
Since most of the compounds are water-soluble, a number
of Li, Na, and K compounds, including chlorides, carbonates and sulfates can be
obtained from natural brines. Some alkali metal compounds such as NaCl, KCl,
and Na2CO3 can be mined as solid deposits. Sodium chloride is also
obtained from seawater (Petrucci, 2011: 89).
The alkaline earth metal of class two is as common as
elements of group one. Calcium and magnesium are the most abundant. Even
beryllium, a member of the second group of the least abundance, can be reached
because it is deposited in the beryl mineral, Be3Al2Si6O18. The major forms in which the other two classic elements
are found are carbonates, sulfates, and silicates (Sunarya, 2010:
334-335).
The group according to the IUPAC rule is made up of 18
classes, whereas according to American rules it consists of two classes, namely
class A (main group: IA-VIIIA) and class B (transition group: IB-VIIIB). The
position of elements (classes and periods) in the periodic system can be
determined by their electron configuration. The class number indicates the
number of valence electrons, the period number indicates the number of skin
(Untoro, 2010: 121)
Most of the alkaline compounds are soluble in water so
that the precipitation test is not possible to be used for identification.
Fortunately, each alkali metal produces a characteristic flame color if the
alkali compound is burned in a flame. The visible colors of each metal are dark
red (lithium), yellow (sodium), lilac (potassium), red violet (rubidium), and
blue (cesium) (Kristian H.S. and Retno D.S., 2010: 109).
The alkaline earth group is silvery white and has a
relatively low density (density) and increases with the number of atoms except
calcium. The alkaline earth metal is less reactive or less electropositive than
the alkali metal but more reactive than the other metals. Such as Ca, Sr, and
Ba samples react with cold water (Kristian H.S. and Retno D.S., 2010: 130).
The elements in one group have many chemical properties,
the chemical properties are determined by the valence electrons, the electrons
in the outer shell of the skin. Because the valence electrons of the same group
of elements are themselves the same (Sukardjo, 1985: 150) .
The most striking feature of alkali and alkaline earth
metals is
Its activity is enormous. Because these metals are so active that they do not exist as an element, when in contact with air or water. None of the IA and IIA elements exist in nature in its elemental state. All elements of alkali are present in the natural compounds As a unipositive ion (positive-one), all the alkaline earth elements are present as positive (positive-two) ions (Keenan, 1980: 89).
Its activity is enormous. Because these metals are so active that they do not exist as an element, when in contact with air or water. None of the IA and IIA elements exist in nature in its elemental state. All elements of alkali are present in the natural compounds As a unipositive ion (positive-one), all the alkaline earth elements are present as positive (positive-two) ions (Keenan, 1980: 89).
Tools and materials:
Tools to be used:
1.
Test tube
2.
Reaction tube
shelf
3.
Nichrome wine
4.
Drop pipette
5.
Bunsen
6.
Woop clamp
7.
Napkin
Materials to be used:
1.
BaCl2 solution
2.
CaCl2 solution
3.
KCl solution
4.
SrCl solution
5.
NaCl solution
6.
Dense HCl solution
7.
NaBr solution
8.
Distilled water
9.
Ammonium carbonate solution
10.
Ammonium sulfate solution
11.
Nitric acid
12.
Tetrachloride solution
Work steps:
Results and
Discussion:
Discussion:
The flame color of each element has distinct characteristics. This is
consistent with the experimental results with the literature.
In the class IIA occurs sediment and in group IA does not occur sediment. Ammonium sulfate, ammonium carbonate, and ammonium phosphate have their own characteristics or characteristics. In ammonium sulfate is soluble in water and causes precipitation. Ammonium carbonate is a colorless and water-soluble crystal. Whereas ammonium phosphate is colorless and also readily soluble in water. The presence or absence of sediment due to class IA is easy to laryt and is strong base, while group IIA is weak base and difficult to dissolve. This is in accordance with Petrucci's opinion (2011: 89).
Conclusion:
1.
In the periodic
table, each element lies in a certain class and period so that there are groups
that have the same properties as elements located in one group have the same
properties.
2.
Color test flame tested various and each element has a
distinctive color.
3.
In addition to the flame test, the precipitation test is
also carried out to identify whether the element is considered alkaline or
alkaline earth.
Literature:
Keenan.dkk.(1984).Kimia untuk Universitas. Jakatra :
Erlangga.
Petrucci.2011.Kimia
Dasar. Jakarta: PT.Gelora Aksara Pratama.
S, Kristian H. Dan Retno
D. S.2010.Kimia Anorganik Logam. Yogyakarta: Graha Ilmu.
Sukardjo. 1998.Kimia
anorganik. Jakarta : Erlangga.
Sunaryan, Yayan.2010.Kimia
Dasar 1. Bandung: Yrama Widya.
Untoro, Joko.2010.Kimia Dasar. Yogyakarta: Paradigma.
Attacment:
In your flame experiment, I see you using a red flame. If using a blue or green flame does the result remain the same?
BalasHapusThe results remain the same, because each element has a distinctive color.
HapusWhy we must take a nichrome wire in the fire until brown before we used again to another solution?
BalasHapusSo that in the next flame test is not disturbed by the presence of substances attached to the previous nikrom wire
HapusHow to identification radioactive?
BalasHapus@hudiahudhud
Can use its properties:
Hapus1. Can penetrate paper or thin metal slabs.
2. Can ionize the illuminated gas.
3. Can blacken the film plate.
4. Causing ZnS-coated substances to fluoresce (fluorescence).
5. Can be described by the magnetic field into three beams of light, ie rays α, β,
And γ.
What is the difference between alkali and alkaline soils based on your experiment?
BalasHapusThe flame color of each element has distinct characteristics. This is consistent with the experimental results with the literature. The presence or absence of sediment due to class IA is easy to laryt and is strong base, while group IIA is weak base and difficult to dissolve.
HapusWhat are the benefits of this experiment?
BalasHapusCan know the similarities and differences of alkaline and alkaline earth elements, can prove in practice, more familiar with the properties of elements in the periodic, and help to better recognize the reaction that occurred.
HapusAmmonium sulfate, ammonium carbonate, and ammonium phosphate have their own characteristics or characteristics. What are the characteristics?
BalasHapusIn ammonium sulfate is soluble in water and causes precipitation. Ammonium carbonate is a colorless and water-soluble crystal. Whereas ammonium phosphate is colorless and also readily soluble in water.
HapusWrite an example of the reaction equation of alkali and alkaline earth?
BalasHapusFor example alkali reaction: Na (s) + NH3 (l) -> NaNH2 (s) + ½ H2 (g)
HapusExamples of alkaline earth reactions: 6CaO + 2Al 3 Ca + Ca3Al2O6
What is the tendency of the reactivity of alkali metals from Li to Fr?
BalasHapusAll alkali metals from Li to Fr have the same valence electrons, ie 1. However, the size of the alkali metal positive ions increases from Li to Fr. Therefore the possibility for valence electrons to collide with positive ions is increasing. In other words, electrical and heat conductivity tend to decrease from Li to Fr.
HapusWhat is the difference of class and elments of the results obtained?
BalasHapusGroups are vertical columns in the periodic system. That is, the periodic system is distinguished by horizontal on the periodic table. Take a look at the periodic table. Different groups have different properties, but the same group has the same properties. Thus, in chemistry the determination of properties by group. When examined, all substances are formed from the simplest parts called elements. In general, groups have the same number of elements because in the periodic table has a number of 7 periods. But for the class of transition elements it has a lot of elements such as lanthanides and actinides.
HapusAs we know class IA is an alkali metal group. So why is hydrogen included in group IA, whereas hydrogen is not metal?
BalasHapusHydrogen is a water-forming element in which if hydrogen is solidified in a certain concentration they will form a water point. Alkali metals are characteristic if they are reacted with water they will form alkaline hydroxide ions with a pH of more than 7. While hydrogen is the water itself and if reacted with water will not cause any change.
Hapus