Chem Post Lab Discussion

8/13/2019 Chem Post Lab Discussion

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EXPERIMENT 6CLASSIFICATION OF COMPOUNDSClassifications of compounds according

to the kind of element present1.Acids -

compounds containing H

+

ions in solution which whenionized break up into H+ and anion.

2.Bases-compounds containing OH-in solution which when ionized

break up into a cation and OH-.

3.Salts- compounds containing a cation except H+ and anion

except OH-. Salts are formed from the reaction of a base with an

acid (neutralization reaction). They are usually ionic or

electrovalent compounds and are strong electrolytes.

Objective: To differentiate solutions of acid bases and salts by

color reaction to indicators


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Acid Base

Taste sour Bitter taste

pH less than 7 pH greater than 7

Turns blue litmus paper to red Turns red litmus paper to

blueNeutralize bases producing salt

and water

neutralize acid producing salt

and water

Acids are electrolytes Bases are electrolytesAcid reacts with active metals to

Produce hydrogen

Bases are slippery

Properties of Acids and Bases


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Substances

tested

Red

Litmus

Paper

Blue

Litmus

paper

phenolphthalein classification

1M aceticacid

1M NaOH

Soap solution

Dilute pineapple

juice

Liquid soza

sprite

Diet cola

Would you classify vinegar as an acid?

Yes vinegar is an acid. It is 3 to 6 % acetic acid(CH3COOH)

and is classified as a weak acid.


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Neutralization- It is a chemical reactionin which an acidand abasereact to form a saltA neutralization reaction is a type of

double replacement reaction. Typically, the resulting solution

produced by the reaction consists of a salt and water. The generalformula for acidbase neutralization reactions can be written as

acid + base salt + water

HA + BOH BA + H2O

where HA represents the Arrhenius acid, BOH represents the

Arrhenius base, and BA is the salt produced. Notice how, typical

of a double replacement reaction, the cationsand anionsof the

substances merely switch places.

An example reaction of this form is the reaction between

hydrochloric acid(HCl) and sodium hydroxide(NaOH):

NaOH + HCl NaCl + H2O

Water and sodium chloride, or common table saltare produced.
http://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Salt_(chemistry)http://en.wikipedia.org/wiki/Salt_metathesis_reactionhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Sodium_hydroxidehttp://en.wikipedia.org/wiki/Sodium_chloridehttp://en.wikipedia.org/wiki/Table_salthttp://en.wikipedia.org/wiki/Table_salthttp://en.wikipedia.org/wiki/Sodium_chloridehttp://en.wikipedia.org/wiki/Sodium_hydroxidehttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Salt_metathesis_reactionhttp://en.wikipedia.org/wiki/Salt_(chemistry)http://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Chemical_reaction


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EXPERIMENT 7TYPES OF CHEMICAL REACTIONSOBJECTIVE: To be able to explain the different types of chemical reaction.

A chemical react ionis the change of a substance into a new one

that has a different chemical identity.

A chemical reaction is usually accompanied by easily observed

physical effects, such as the emission of heat and light, the

formation of a precipitate, the evolution of gas, or a color change.

Absolute confirmation of a chemical change can only be validated

by chemical analysis of the products!


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Four introductory types of chemical reaction:Combination/direct union- two or more substances being

combined into a single compound. These reactions come in the

general form of: A + B ---> AB

a) 2Cu + O2---> 2CuO

b) 2Mg + O2---> 2MgO

Decompositiona compound is broken into two or more

substances

Heat or light is usually applied in order to decompose the

Compound. These reactions come in the general form of:

AB ---> A + B

KClO3---> KCl O2


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Single replacement occurs when one element displaces

another from a compound or aqueous solution. These

reactions come in the general form of:

A + BC ---> AC + Ba.) Zn + HCl---> ZnCl

2+ H

2

b.) CuSO4+ Fe---> FeSO

4+ Cu

Double replacement/methathesis

two compounds exchangeanions.These reactions come in the general form of:

AB + CD ---> AD + CB

Copper cannot replace hydrogen inHCl because copper is

listed below H2in the activity series of metal, meaning no

reaction because Cu is considered a less active metal and it

cannot displace hydrogen from any source

a.) AgNO3+ NH4Cl---> AgCl + NH4NO3b.) CaCl2 + Na2CO3---> CaCO3+ 2NaCl


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EXPERIMENT 8OXIDATION REDUCTION REACTIONOBJECTIVE: a.) To study some of the oxidation-reduction reactions.

Redox reactions, or oxidation-reductionreactions, have a

number of similarities to acidbase reactions. Like acidbase

reactions, redox reactions are a matched set, that is, there

cannot be an oxidation reaction without a reduction reaction .Reduction and oxidation happen together.

b. To show how oxidation-reduction take place when twotypes of substances is mixed to form another compound.
http://en.wikipedia.org/wiki/Acid%E2%80%93base_reactionhttp://en.wikipedia.org/wiki/Acid%E2%80%93base_reactionhttp://en.wikipedia.org/wiki/Acid%E2%80%93base_reactionhttp://en.wikipedia.org/wiki/Acid%E2%80%93base_reactionhttp://en.wikipedia.org/wiki/Acid%E2%80%93base_reactionhttp://en.wikipedia.org/wiki/Acid%E2%80%93base_reaction


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Oxidation refers to the loss of electrons, while reduction

refers to the gain of electrons. The number of electrons gained

always equal to the number of electron lost.

The losing of electrons by a reactant is called oxidation.

The gaining of electrons by a reactant is called reduction.

Oxidation number is a number that tells how many electronsare lost or gained by an atom. It is either positive(+)or

negative(-).

If a neutral atom loses electrons it then becomes positively

charged, it has a positive oxidation number.If a neutral atoms gains electrons, it becomes negatively

charged, it has a negative oxidation number.

Uncombined elements has an oxidation number of zero.
http://www.shodor.org/UNChem/glossary.htmlhttp://www.shodor.org/UNChem/glossary.html


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EXPERIMENT 9PREPARATION AND PROPERTIESOF OXYGENOBJECTIVE: To be able to observe properties of oxygen.

Density : 1.429

OXYGEN

Is the most abundant element on earth

Is the most reactive of the commonly known nonmetalsIt forms compounds with all metal and nonmetalsIt is essential to most combustion, corrosion and life processesOxygen, O2, is a colourless odourless gaseous main group

element which belong to Group VIbof the periodic table.

Atomic Number : 8

Atomic Mass : 15.9994

Melting Point : -214 degC

Boiling Point : -183 degC
http://www.ucc.ie/academic/chem/dolchem/elem/group.htmlhttp://www.ucc.ie/academic/chem/dolchem/elem/group.html


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Potassium chlorate decomposes at a low temperature if

previously mixed with manganese dioxide which is a catalyst

for the decomposition. :

2 KClO3 ==> 2 KCl + 3 O2

Preparation of oxygen Using potassium chlorate
http://www.ucc.ie/academic/chem/dolchem/dict/000c1.htmlhttp://www.ucc.ie/academic/chem/dolchem/dict/000c1.html


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EXPERIMENT 10PREPARATION AND PROPERTIES OFHYDROGEN

OBJECTIVE:To demonstrate various methods by which hydrogen gas may beproduced and to learn some of the chemical and physical properties of hydrogen

gas.

The element hydrogen (H) has the lowest atomic weight

(1.008 amu), and is the least dense of any known substance.Because of hydrogen's low density (1/14 the density of air),

balloons filled with hydrogen will float. Because of the

hydrogen molecule's small size, it will diffuse through many

substances.

Hydrogen (H2) is a diatomic gas (two atoms) that is tasteless,

colourless, and odourless and is the lightest element.

Hydrogen


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Hydrogen gas can be generated in the laboratory by various

chemical means

Hydrogen gas is extremely flammable and will react with

oxygen to form water with a release of a great deal of heat.

The element hydrogen is the ninth most abundant element on

earth, but is the third most common element found in all known

compounds.

The sun is made up almost entirely of hydrogen gas, which

is continually undergoing fusion.


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EXPERIMENT 10RELATIVE ACTIVITIES OFSOME ELEMENTSOBJECTIVES: To be able to study the relative activity of elements by

observing the relative rate of release of hydrogen.

The Activity Series of the metals is an invaluable aid to

predicting the products of replacement reactions. It also

can be used as an aid in predicting products of some other

reactions.

Activity Series of Metals


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The notes below will help you make better use of the activity

series than just the list of metals by themselves.

Each element on the list replaces from a compound any of

the elements below it. The larger the interval between

elements, the more vigorous the reaction.

The first five elements (lithium - sodium) are known as very

active metals and they react with cold water to produce thehydroxide and hydrogen gas.

The next four metals (magnesium - chromium) are considered

active metals and they will react with very hot water or steam

to form the oxide and hydrogen gas.

The oxides of all of these first metals resist reduction by H2.


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The last five metals (mercury - gold) are often found free in

nature, their oxides decompose with mild heating, and they

form oxides only indirectly.

The next six metals (iron - lead) replace hydrogen from HCl

and dil. sulfuric and nitric acids. Their oxides undergo

reduction by heating with H2, carbon, and carbon monoxide.

The metals lithium - copper, can combine directly with

oxygen to form the oxide.


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EXPERIMENT 2AWATER AND ITS PROPERTIES

c. To be able to learn the different techniques in waterpurification.

OBJECTIVES: a. To be able to know the importance of water.b. To be able to know the different physical andchemical properties of water.


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DISTILLATION SET-UP

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Chem Post Lab Discussion