7/30/2019 Topic 8 Salts
1/29
X INTRODUCTION
Hello and welcome to the final topic of this module! Well, first of all, I am sureyou are aware that chemical salts are part of our daily life. We use sodiumchloride and monosodium glutamate or MSG in food preparation, ammoniumnitrate and urea as fertilisers, mercury (II) chloride and copper(II) sulphates inpesticides, sodium benzoate and sodium nitrate as preservatives in our food andso on.
In addition, most of the medications we take are salts in tablet form. As anexample, for gastric pain due to digestive acids, we take antacids such as natriumhydrogen carbonate, which is a base to neutralise the digestive acids. Anotherfamiliar and popular example is Panadol or paracetamol which we use to relieveheadaches and fever. For indigestion and bloatedness, we use ENO salt.
LEARNING OUTCOMES
By the end of this topic, you should be able to:1. Explain how soluble salts and insoluble salts can be prepared;
2. Explain how cations and anions in salts can be identified;
3. Conduct tests to identify gases;
4. Describe how salt can be prepared by crystallisation; and
5. Identify the ions present in an unknown salt using qualitativeanalysis.
TTooppiicc
88X Salts
7/30/2019 Topic 8 Salts
2/29
TOPIC 8 SALTS W 191
Epsom salts or magnesium sulphate crystals are used for relaxing muscles, as asedative and to draw toxins from our body. The examples can go on and on
because there are so many uses of salts in our daily lives; it is just a matter of
whether we realise it or not.
So, in this topic, we will learn more about salts, how they are prepared, howcations and anions in salts can be identified, how cations and anions in salts can
be analysed through qualitative analysis as well as how salts can be obtained intheir crystalline form through the process of crystallisation. Are you ready tostart now? Let this exciting lesson begin and enjoy this final topic!
PREPARATION OF SALTS
We begin this topic by discussing salt. Before we proceed further, what can yousay to define salt?
There are many different types of salts which exist in nature. The earth crustcontains different types of salt such as calcium chloride, magnesium sulphateand calcium carbonate. There are also salts such as potassium chloride,magnesium chloride and potassium bromide. Keep in mind that not all salts aresoluble in water. There are soluble salts and insoluble salts. In Topic 7, we learntthat the solubility of a substance is the amount of that substance (solute) that can
be dissolved in a given quantity of solvent. Can you still recall? What does itmean by soluble salts?
8.1
are salts that d while s are called i .
A s is an i that contains a c
and an a .
7/30/2019 Topic 8 Salts
3/29
X TOPIC 8 SALTS192
However, some salts that do not dissolve in water at room temperature dodissolve in hot water such as lead(II) chloride. You can refer to Table 8.1, whichgives you a summary of soluble and insoluble salts.
Soluble and Insoluble Salts
x Nitrate Salts
x Sodium
x Potassium
x Ammonium Salts
x Ethanoate Salts
x Chloride salts: All are soluble except s ,(soluble in hot water) and m
x Sulphate salts: All are soluble except l ,, and c (dissolves a little
bit in water)
x
Carbonate salts: All are insoluble except sodium carbonate,potassium carbonate and ammonium carbonate
We can prepare both soluble and insoluble salts using various methods. Themethods used depend on the salts solubility in water. These methods will bediscussed in the following sections.
8.1.1 Preparation of Soluble Salts
Do you know that there are three methods to prepare soluble salts? These
methods are a , d , and. Then, the salt solutions formed are e ,
, f , and d to obtain dry salt crystals. Figure 8.1 shows thepreparation of soluble salts.
7/30/2019 Topic 8 Salts
4/29
TOPIC 8 SALTS W 193
Preparation of soluble salts
http://wiki.one-school.net
7/30/2019 Topic 8 Salts
5/29
X TOPIC 8 SALTS194
Now, let us study these three methods further, starting with neutalisationreactions.
(a) NFirstly, let us learn the definition of neutralisation reaction. What does itstand for?
Do you know which salts can be prepared this way? Salts of s ,, and a can be prepared by neutralisation reactions.
How does this method work? This method works by neutralising the acidby a base/alkali, thus producing the end products which are salt and water.This process can be simplified as follows
Acid + Base/Alkali Salt + Water(Neutralisation)
One typical example for this particular method is the reaction betweenhydrochloric acid (acid) and sodium hydroxide (base) to form sodiumchloride (salt) and water.
HCl(aq) + NaOH (aq) NaCl(aq) + H2O (l)
From this example, we can also define salt as a compound that is formed
when the hydrogen ion, H+
, from an acid is replaced by a metal ion orammonium ion from the base/alkali.
A salt is also an i which consists of a cation such as a metalion or an ammonium ion from a base and anion from an acid. For example,in the salt sodium chloride, the cation is sodium ion, Na+, and the anion isthe chloride ion, Cl.
are processes in which an ato form s and w .
7/30/2019 Topic 8 Salts
6/29
TOPIC 8 SALTS W 195
Other soluble salts can also be prepared through neutralisation by havingan acid react with a metal oxide, just as shown in the following:
Acid + Metal Oxide Salt + Water(neutralisation)
An example for this method is when you have hydrochloric acid (acid) reactwith magnesium oxide (base) to form magnesium chloride (salt) and water.
HCl(aq) + MgO (aq) MgCl2(aq) + H2O (l)
Table 8.2 shows some examples of salts from different acids.
Examples of Salts from Different Acids
Sulphuric acid Magnesium sulphateAmmonium sulphate
MgSO4(NH4)2 SO4
Nitric acid Potassium nitrateAluminium nitrate
KNO3Al (NO3) 3
Carbonic acid Iron(II) carbonate
Calcium carbonate
FeCO3
CaCO3
Phosphoric acid Iron(III) phosphateAmmonium phosphate
FePO4(NH4) 3PO4
Ethanoic acid Lead(II) ethanoateCopper(II) ethanoate
Pb (CH3COO) 2Cu (CH3COO) 2
Hydrochloric acid Sodium chlorideAmmonium chloride
NaClNH4Cl
(b)
Now, let us move on to the second method of preparing soluble salt displacement reactions. How does this method work? In this method, saltsare prepared by reacting non-oxidising acids such as hydrochloric acid andsulphuric acid with active metals, just as shown in the following:
Acid + Metal Salt + Hydrogen gas
7/30/2019 Topic 8 Salts
7/29
X TOPIC 8 SALTS196
For example, when zinc is dissolved in sulphuric acid, the reactionproduces zinc sulphate; hydrogen is displaced from the acid and it bubblesoff as gaseous H2, just like the following equation:
H2SO4(aq) + Zn (s) ZnSO4(aq) + H2 (g)
Zinc sulphate solution is then evaporated, cooled and filtered to get solidcrystals. The reaction is an example of a displacement reaction in which oneelement displaces another from a compound. The more active the metal(Zn) displaces, the less active it is for hydrogen from its compound inaqueous solution to form zinc sulphate and hydrogen gas.
(c) RLastly, let us look at the third method, which is reaction of acids withcarbonates. What does reaction of acids with carbonates yield? Reaction ofacids with carbonates yields salt, water and carbon dioxide gas as shown inthe following:
Acid + Carbonates Salt + Water + Carbon dioxide gas
For example, calcium chloride salt is prepared by the reaction betweenhydrochloric acid and calcium carbonate. Carbon dioxide gas bubbles off andthe salt solution is then evaporated, cooled and filtered to obtain calciumchloride crystals.
2HCl(aq) + CaCO3 (aq) CaCl2(aq + H2O (l) + CO2(g)
Let us now learn how to prepare ammonium sulphate salt in Activity 8.1.
7/30/2019 Topic 8 Salts
8/29
TOPIC 8 SALTS W 197
You will need: ammonia solution (2M), dilute sulphuric acid (1M),beaker, glass rod, bunsen burner, tripod stand, wire gauze, filter funnel,and filter paper.
Step:
1. Heat 30 cm3 of dilute sulphuric acid into a beaker.
2. Add ammonia solution little by little into the beaker, stirring thesolution.
3. Do not add any ammonia solution when the solution smellsamniotic.
4. Heat the solution until it becomes one-third of its original volume.
5. Cool the hot saturated solution in a mixture of ice and water.
6. Filter the salt crystals produced.
7. Dry the crystals using filter paper.
Questions:
(a) Which method is used to prepare the salt?
(b) How does the addition of ammonium sulphate affect the pH of thesoil?
ACTIVITY 8.1
7/30/2019 Topic 8 Salts
9/29
X TOPIC 8 SALTS198
8.1.2 Preparation of Insoluble Salts
Let us move on to insoluble salts. How do we prepare it?
What are the steps involved for this method? Figure 8.2 shows the steps involved
in the preparation of insoluble salts.
Preparation of insoluble salts by precipitationhttp://www.docbrown.info/page03/AcidsBasesSalts06.htm
are prepared by p ,which are processes in which t are m to form a soluble salt and an insolublesalt as a precipitate that can be obtained by filtration.
7/30/2019 Topic 8 Salts
10/29
TOPIC 8 SALTS W 199
A typical example of precipitation is the preparation of the insoluble salt, bariumsulphate. This is shown in Figure 8.3.
Preparation of barium sulphatehttp://wiki.one-school.net
You may notice that both starting solutions of barium chloride and magnesiumsulphate are soluble in water. The reaction between the two solutions yields aprecipitate, barium sulphate, and a soluble salt, magnesium chloride, as shown inthe following:
BaCl2 (aq) + MgSO4(aq) BaSO4(s) + MgCl2(aq)
7/30/2019 Topic 8 Salts
11/29
X TOPIC 8 SALTS200
How do we predict whether a precipitation reaction will occur or not? In order topredict whether a precipitation reaction will occur on mixing solutions of twosubstances, you must know the solubilities of the potential products. This can be
done by using the solubility guidelines in Table 8.1 shown earlier. Can you stillrecall?
Based on Table 8.1, we can conclude that if a substance has a low solubility inwater, it is likely to precipitate from an aqueous solution. If a substance has ahigh solubility in water, no precipitate will form from this reaction.
IDENTIFICATION OF CATIONS ANDANIONS
Thus far, we have learnt about the formation of ions in Topic 5. An ion is an atomor group of atoms that carries an electric charge. Ions that possess a positivecharge, such as sodium ion, Na+, are called cations. Those carrying a negativecharge, such as chloride ion, Cl, are called anions. Ions also exist as polyatomicions or groups of atoms that bear an electric charge.
The first atom in the formula is usually the central atom to which the other atomsare bonded to make a stable unit. Examples include the ammonium ion, NH4+,the sulphate ion, SO42 and the nitrate ion, NO3.
8.2
Search in the Internet and find out the uses of salt in:
(a) Agriculture;
(b) Medical field; and
(c) Food industries.
ACTIVITY 8.2
7/30/2019 Topic 8 Salts
12/29
TOPIC 8 SALTS W 201
Table 8.3 shows the formula, ionic charges and names of some common ions.
Some Common Cations and Anions
Li+ 1+ Lithium F 1 Flouride
Na+ 1+ Sodium Cl 1 Chloride
K+ 1+ Potassium Br 1 Bromide
Ag+ 1+ Silver/argentum I 1 Iodide
NH4+ 1+ Ammonium OH 1 Hydroxide
Cu+ 1+ Copper(I) MnO4 1 Permanganate
Cu2+ 2+ Copper(II) CH3COO 1 Ethanoate/acetate
Mg2+ 2+ Magnesium NO3 1 Nitrate
Ca2+ 2+ Calcium O2 2 Oxide
Zn2+ 2+ Zinc O22 2 Peroxide
Hg22+ 2+ Mercury(I)/mercurous CO32 2 Carbonate
Hg2+ 2+ Mercury(II) ofmercuric
CrO42 2 Chromate
Fe2+ 2+ Iron(II) Cr2O72 2 Dichromate
Pb2+ 2+ Plumbum(II) S2 2 Sulphide
Sn2+ 2+ Tin(II)/stannous SO42 2 Sulphate
Fe3+ 3+ Iron(III) SO32 2 Sulphite
Al3+ 3+ Aluminium CO32 2 Carbonate
Cr3+ 3+ Chromium PO43 3 Phosphate
In the following sections, we will learn how to identify anions and cations.
7/30/2019 Topic 8 Salts
13/29
X TOPIC 8 SALTS202
8.2.1 Identification of Anions
Do you know that anions are identified by the reaction of the salt or salt solution
with silver nitrate solution or barium chloride solution? These are shown inTable 8.4.
Reactions of Anions
Bromide, Br Pale yellow precipitate No reaction No reaction
Chloride, Cl White precipitatesoluble in ammonia
No reaction No reaction
Iodide, I
Yellow precipitate Red colouration No reactionNitrite, NO2 White precipitate Reddish brown
precipitate on heatingNo reaction
Sulphate, SO42 White precipitate ifsolution isconcentrated
No reaction White precipitateinsoluble in diluteHCl
Sulphide, S2 Black precipitate Black precipitate inalkaline solution
No reaction
Sulphite, SO32 White precipitate
soluble in excesssulphite solution
Red colouration or
brown precipitate
White precipitate
soluble in diluteHCl
8.2.2 Identification of Cations
How about cations? How do we identify them? Cations are identified by reactionof the salt or salt solution with sodium hydroxide or ammonia solution as shownin Figure 8.4.
7/30/2019 Topic 8 Salts
14/29
TOPIC 8 SALTS W 203
Test for cationshttp://wiki.one-school.net
7/30/2019 Topic 8 Salts
15/29
X TOPIC 8 SALTS204
In addition, cations can be identified by a flame test where a small amount ofthe salt is heated on a nichrome wire moisten with concentrated sulphuric acidto produce a flame characteristic of the cations. The characteristic is shown in
Table 8.5.
Flame Test of Some Cations
Green Barium ion, Ba2+
Red Calcium ion, Ca2+
Blue Copper(II) ion, Cu2+
Yellow Sodium ion, Na+
Violet Potassium ion, K+
IDENTIFICATION OF GASES
We turn our attention now to gases. How do we identify gases? First of all,you have to understand that many important chemical substances are gasesat ambient conditions. The earths atmosphere is a mixture of gases such asnitrogen and oxygen with smaller concentration of other gases. When somechemical compounds are heated, gases are also evolved.
For example, when a carbonate salt is heated, carbon dioxide gas is evolved. Eachof these gases has characteristic physical properties and can be identified by itscolour, smell, and test with damp litmus paper as shown in Figure 8.5.
8.3
7/30/2019 Topic 8 Salts
16/29
TOPIC 8 SALTS W 205
Identification of gaseshttp://wiki.one-school.net
7/30/2019 Topic 8 Salts
17/29
X TOPIC 8 SALTS206
The gases that are evolved can be further identified by carrying out confirmatorytests as shown in Table 8.6.
Confirmatory Test for Gases
Carbon dioxide Turns lime water or calcium hydroxide milky due to theformation of calcium carbonate.
Ca(OH)2(aq) + CO2 (g) CaCO3(s) + H2O(l)
Sulphur dioxide Decolourises acidified potassium permanganate solution.
Hydrogen sulphide Decolourises acidified potassium permanganate solution,smells like rotten eggs.
Chlorine Bleaches wet litmus paper.Ammonia Thick, white fumes of ammonium chloride when in contact
with concentrated hydrochloric acid.
NH3(g) + HCl(g) NH4Cl(g)
Oxygen Burns when a lighted splinter is placed inside a gas jar ofoxygen.
CRYSTALLISATION
Let us start this subtopic by defining crystallisation. Do you know what it standsfor?
8.4
is the formation of s from a.
7/30/2019 Topic 8 Salts
18/29
7/30/2019 Topic 8 Salts
19/29
7/30/2019 Topic 8 Salts
20/29
TOPIC 8 SALTS W 209
Do you know that there are three steps of doing qualitative analysis of anunknown salt? These steps are shown in Figure 8.7.
Three steps of qualitative analysis
8.5.1 Preliminary Examination of the Salt
What can we do to preliminary examine the salt? Preliminary examination of thesalt involves these five following tests as listed in Figure 8.8.
Five tests of preliminary examination of salt
7/30/2019 Topic 8 Salts
21/29
X TOPIC 8 SALTS210
Now, we are going to look at these steps further, starting with the first step physical examination of the salt.
(a) We can do preliminary examination by looking, touching and smelling. Bydoing so, we can determine the physical properties of the salt such as itsphysical state, colour and smell. We can always check our observationsagainst Figure 8.9 to infer the salt.
Colour of saltshttp://wiki.one-school.net
7/30/2019 Topic 8 Salts
22/29
TOPIC 8 SALTS W 211
(b) SWe can check the solubility of the salt by dissolving it in water. This can bedone by putting a small amount of the salt in a test tube. Then, we can refer
to Table 8.1 to check the solubility of the salt in water.
(c)This can be done by heating the salt and then observing the colour changeof the salt and the gases that are evolved. These observations can infer thetype of that salt as shown in Table 8.7 and Table 8.8 respectively.
Action of Heat on Salts and Colour Change
Greenish blue Brown Copper(II) chloride
Blue White Copper(II) sulphate
Violet Green Chromium(III) salts
Green White Iron(II) salts
Bright yellow Iron black Iron(III) chloride
Bright green Yellow Nickel(II) salts
White Yellow when hot, white when cold Zinc salt or zinc oxide
Yellow Yellow when cold, brownish-redwhen hot
Lead(II) oxide
White White sublimate Ammonium salts
Yellow Yellow sublimate Sulphur or sulphurcompounds such asthiosulphates, sulphites
7/30/2019 Topic 8 Salts
23/29
X TOPIC 8 SALTS212
Action of Heat on Salts and Gases Evolved
Water vapour Hydrated salt, hydrogencarbonate, hydroxideViolet vapour Iodine or iodine compounds
Oxygen Oxides, peroxides, nitrates, chlorates and others
Carbon dioxide Carbonates, bicarbonates, oxalates and organiccompounds
Ammonia Ammonium salts
Sulphur dioxide Sulphites, sulphates, thiosulphates
Hydrogen sulphide Hydrated sulphides, acid sulphides
Chlorine Hypochlorites, some chlorides
Dark brown or reddish fumes Nitrogen dioxide gas from nitrates, bromine fromcertain bromides
Confirmatory tests are then conducted for specific gases as shown in Table8.6 (Subtopic 8.3).
(d)Now, let us move on to see the reaction of the salt with dilute hydrochcloric
acid. We can do this by adding dilute hydrochloric acid to a small amountof the salt in a test tube. If there is no reaction, then we need to heat themixture slowly. Identify any gases that are evolved to infer the type of saltas shown in Table 8.9.
Action of Dilute Hydrochloric Acid
Reddish brown fumes Nitrogen dioxide from nitrites
Odour of vinegar Acetic acid from acetates
Yellowish green gas which bleaches wet litmus paper Chlorine from hypochlorites
Colourless gas which discolourises acidifiedpotassium permanganate solution (no rotten smell)
Sulphur dioxide from sulphites
Colourless gas which discolourises acidifiedpotassium permanganate solution
(rotten smell)
Hydrogen sulphide gas fromsulphides
Colourless gas which turns lime water milky Carbon dioxide fromcarbonates or bicarbonates
7/30/2019 Topic 8 Salts
24/29
TOPIC 8 SALTS W 213
(e) RLastly, let us look at the reaction of the salt with concentrated sulphuricacid. This can be done by adding concentrated sulphuric acid to a small
amount of the salt in a test tube. If there is no reaction, heat the mixtureslowly. Identify any gases that are evolved to infer the type of salt as shownin Table 8.10.
Action of Concentrated Sulphuric Acid
White precipitate Insoluble sulphates from barium, calciumand lead(II) salts
Colourless gas which fumes in air or
when in contact with ammonia solution
Hydrogen chloride from chlorides
Violet vapour Iodine from iodides
Colourless gas burns with blue flame Carbon monoxide from formates oroxalates
Colourless gas which burns when alighted wooden splinter is placed
Oxygen from peroxides, permangantes,chromates and dichromates
Colourless gas which discolourisesacidified potassium permanganatesolution (no rotten smell)
Sulphur dioxide from sulphites
Colourless gas which discolourisesacidified potassium permanganatesolution
(rotten smell)
Hydrogen sulphide gas from sulphides
Colourless gas which turns lime watermilky
Carbon dioxide from carbonates orbicarbonates
7/30/2019 Topic 8 Salts
25/29
X TOPIC 8 SALTS214
8.5.2 Identification of Anions and Cations in the Salt
How do we identify anions and cations in the salt? Well, this can be done by
preparing an aqueous solution of the salt and do testing for anions and cationspresent in the salt as discussed in Subtopic 8.3.
8.5.3 Confirmatory Tests for Specific Anions andCations
How about confirmatory tests for specific anions and cations? Confirmatory testsfor specific anions and cations can be conducted as described in Table 8.11 andFigure 8.10 respectively.
Confirmatory Tests for Anions
Nitrate ion,NO3
Brown ring test. Put an amount of a solution in a test tube; then,slowly pour concentrated sulphuric acid down the side of the testtube. If the solution is a nitrate, a brown ring is obtained where theacid meets the nitrate solution.
Bromide ion, Br With chlorine water or bleaching powder, a brown colouration isobtained.
Chloride ion, Cl A mixture of solid chloride and solid dichromate on heating withconcentrated sulphuric acid. It liberates reddish-brown fumes ofchromyl chloride.
Iodide ion, I Same method as bromide ion but the organic layer is violet.
Nitrite, NO2 With dilute hydrochloric acid or dilute sulphuric acid, it evolvesbrown fumes of nitrogen dioxide.
How about cations? Cations in the salt solution are confirmed by reacting itwith potassium iodide (KI), potassium thiocyanate (K4Fe(CN)6), and potassium
hexacyanoferrate(III) solution (K3Fe(CN)6) as shown in Figure 8.10.
7/30/2019 Topic 8 Salts
26/29
TOPIC 8 SALTS W 215
Confirmatory tests for cationshttp://wiki.one-school.net
You are given a magnesium sulphate solution.
1. Carry out a qualitative analysis on the magnesium sulphatesolution; and
2. Describe briefly the chemical tests done to identify and confirmthe presence of anions and cations in the solution.
ACTIVITY 8.4
7/30/2019 Topic 8 Salts
27/29
X TOPIC 8 SALTS216
x A salt is an ionic compound that contains a cation other than H+ and an anionother than OH or O2. It is formed when the hydrogen ion, H+, from an acidis replaced by a metal ion or ammonium ion from the base/alkali.
x Soluble salts include nitrate salts, salts of sodium, potassium, and ammonium,
and ethanoate salts.
x All chloride salts are soluble except silver chloride, lead(II) chloride (solublein hot water) and mercury(II) chloride.
x All sulphate salts are soluble except lead(II) sulphate, barium sulphate andcalcium sulphate (dissolves a little bit in water).
Answer the questions below:
1. Ammonia gas is bubbled into a test tube filled with a copper(II)sulphate solution. A blue precipitate is formed. What willhappen to the blue precipitate when ammonia gas iscontinuously bubbled into the test tube?
2. How would you differentiate a barium chloride and a bariumnitrate solution?
3. Salt X is soluble in water. The solution is divided into two
portions:
(a) The first portion produces a white precipitate with asodium hydroxide solution. The precipitate will dissolvewhen placed in excess sodium hydroxide solution; and
(b) The second portion gives a yellow precipitate withpotassium iodide.
Based on the above description, name salt X.
SELF-CHECK 8.1
7/30/2019 Topic 8 Salts
28/29
TOPIC 8 SALTS W 217
x All carbonate salts are insoluble except sodium carbonate, potassium carbonateand ammonium carbonate.
x
Soluble salts can be prepared by acid-base neutralisation reactions,displacement reactions, and reaction of acids with carbonates.
x Insoluble salts are prepared by precipitation reactions.
x Anions are identified by the reaction of the salt or salt solution with silvernitrate solution or barium chloride solution.
x Cations are identified by reaction of the salt or salt solution with sodiumhydroxide or ammonia solution.
x Gases can be identified by their colour, smell and a test with damp litmuspaper.
x Crystallisation is the formation of solid crystals from a homogenous solution.
x Qualitative analysis is a procedure for identifying the ions present in anunknown salt.
x Qualitative analysis of an unknown salt involves the following steps:preliminary examination of the salt, identification of anions and cations in the
salt, and confirmatory tests for specific anions and cations.
Anions
Carbonates
Cations
Chloride saltsCrystallisation
Displacement reaction
Gases
Insoluble salts
Nitrates
Neutralisation reaction
Precipitation reaction
Qualitative analysisSalt
Soluble salts
Solubility of salts
Sulphates
7/30/2019 Topic 8 Salts
29/29
X TOPIC 8 SALTS218
Briggs, J. G. R. (1992). Science in focus chemistry for GCE O Level. Singapore:Pearson Education.
Brown, T. L., Lemay, H. E., & Bursten, B. E. (2000). Chemistry: The central science(8th ed.). New Jersey: Prentice Hall.
McMurray, J., & Fay, R. C. (2001). Chemistry(3rd ed.). New Jersey: Prentice Hall.
Ralph, A. B. (2003). Fundamentals of chemistry. New Jersey: Prentice Hall.
Whitten, K. W., Davis, R. E., Peck, M. L., & Stanley, G. G. (2010). Chemistry(9th ed.). Belmont: Brooks/Cole.