3 Chemistry

8/13/2019 3 Chemistry

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CHEM ISTRY FOR MUD ENGINEERS


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WHO NEEDS TO KNOW

ABOUT CHEMISTRY?


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Chemistry

Chemistry is the branch of science whichseeks to answer the questions:

1. What are substances composed of ?

2. How are their properties related to

their composition ?

3. How does one substance interact with

another and with energy ?


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Matter

Matter is anything that occupies space andhas mass. Matter may exist in any one of

three states - solid, liquid or gas.

Ice - Solid

Water - LiquidSteam - Gas


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Classification of Matter

Homogeneous Heterogeneous

A Pure

Substance

A Mixture of

Pure Substances


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Pure Substance

Matter which cannot be separated intoother substances by physical means; any

part of a pure substance has the same color,melting point, specific gravity, etc.

- Table salt is a pure substance- Butter is a mixture


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Compound

A substance which can be resolved into twoor more simpler substances.

Examples:

Silver Nitrate Sulfuric Acid

Barium Sulfate Hydrogen Sulfide

Calcium Hydroxide Sodium Hydroxide

Hydrogen Oxide Sodium Carbonate


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Decomposition

In chemical decomposition asubstance is broken down into two or

more simpler substances.

EXAMPLE

2KClO3 + Heat 2KCl + 3O2

Potassium + Heat Potassium + Oxygen

Chlorate Chloride


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Elements

Some substances cannot be decomposed bymethods to decompose compounds, and they

cannot be produced by combinations ofother substances in ordinary chemicalchanges.

These substances are called elements.


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Atom

The smallest unit

into which anelement can be

divided and still

retain its identityas that element.

..............


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Atomic Number

Thenumber of

protons in

an atoms

nucleus

.............. N

PP


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Atomic Weight

The relative weight of an element ascompared with one atom of carbon using

12.0000 as the weight of one atom of carbon- 12.

EXAMPLE:Atomic weight of sodium is 22.990


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Elements of Interest to theMud Engineer

Name Symbol Valence Atomic N Atomic Wt

Aluminum Al 3 13 26.982

Barium Ba 2 56 137.33

Calcium Ca 2 20 40.08

Carbon C 2, 4 6 12.011Chromium Cr 3, 6 24 51.996

Chlorine Cl 1, 3, 5, 7 17 35.453

Hydrogen H 1 1 1.0079

Magnesium Mg 2 12 24.305

Nitrogen N 3, 5 7 14.007

Oxygen O 2 8 15.999

Potassium K 1 19 39.098

Silicon Si 4 14 28.0855

Silver Ag 1 47 107.868

Sodium Na 1 11 22.990

Sulphur S 2, 4, 6 16 32.06


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Atoms Have Valence

Valence is defined as a number whichrepresents the number of atoms of

hydrogen or its equivalent that willcombine with, or be replaced by, the atomin question.

The outer ring of planetary electrons arecalled the valence electrons because theytake part in chemical change.


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Atoms have either positive (+) or negative (-) valence.

When the outermost orbit contains a small amount of

electrons, they tend to give up electrons (positivevalence).

When the outer orbit is nearly full of electrons, they

tend to want to fill the orbit or receive electrons(negative valence).

Depending on the amount of electron transfer, the bondis ionic or covalent.

Atoms Have Valence


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11P

SODIUM (Na )+

17P

CHLORI(l

Sodium has a single electron in the outer shell.

This electron can be lost or shared in chemical reaction.

Thus, sodium has a positive valence of 1.

Chlorine needs a single electron to complete the outer shell.

Thus, it needs to gain one electron for stability and therefore has a negative valenceof 1.

It is easy to see that one atom of sodium will combine with only one atom of chlorine

to form one molecule of sodium chloride. The chemical formula for salt (NaCl)

describes the molecule and defines the number and kinds of atoms in the atomic

structure.


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20P

17P17P

Take calcium and chlorine. Combined, 1 calcium

reacts with 2 chlorine atoms to form CaCl2.

Calcium, Ca, Atomic No. 20

Chlorine, Cl, Atomic No. 17


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Ions

+

CATIONS

Positivelycharged ions

Completelygives away

electrons

-

ANIONS

Negativelycharged ions

Completelytakes

electrons


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Covalent Bond

When electrons are shared between atoms toform a bond.

Each hydrogen has equal affinity for electrons, so

one cannot take an electron from the other.However, they can share electrons.

++

H+H

+

:


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Molecule

The smallest unit in

which a compound can

exist and still retain theproperties of that

compound.

Molecules are held

together with covalent

bonds.

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Solubility

The measurement of the

quantity of solute that

will dissolve in a

quantity of solvent togive a saturated

solution.

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Solvent

The substance that does the dissolving.

Example:

Water (H2

O)

Water


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Solute

The substance that is dissolved.

Example:

Salt (NaCl)Salt


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Solution

A true solution

cannot be

filtered out.

Examples:

NaCl + HOH

NaOH + HOH

Na

Na

Cl

Cl

+

--

+

Na

Cl-

+


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Solubility is a Function of:

Temperature

pH

Pressure

Other ions present


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Solubility of Compounds as aFunction of Temperature

Compound 0C 20C 40C 60C 80C 100C

Ca(OH)2 0.185 0.165 0.141 0.116 0.094 0.077

KCl 27.6 34.0 40.0 45.5 51.1 56.7

NaCl 35.7 36.0 36.6 37.3 38.4 39.8

CaSO42H2O 0.176 0.202 0.210 0.197 0.182 0.162

CaCl2 59.5 74.5 115.3 136.8 147.0 159.0

CaCO3 -- 0.0012 -- -- -- 0.002

(Grams of compound per 100 grams of water)


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pH

Measurement of the hydrogen ion

concentration.

pH = log1

[H+]


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In one liter of pure water the H+and OH-

ion concentrations are the same.

1 x 10-7 = H+ions

1 x 10-7 = OH-ionsOH-

OH-

OH-

H+

H+

H+


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The product of the H+ion and OH-ion

concentrations in pure water or any

water solution is always 1 x 10-14.

10-7 x 10-7 = 10-14


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pH / Pf - Alkalinity

The effect of using caustic soda alone to increase the pH(with no alkalinity due to carbonates or bicarbonates):

pH NaOH, ppb Pf OH, ppm

9 0.00014 0.0005 0.17

10 0.0014 0.005 1.7

11 0.014 0.05 17.0

12 0.14 0.5 170.013 1.4 5.0 1,700.0

14 14.0 50.0 17,000.0

NOTE: Each time the concentration of NaOH goes upby a factor of 10, the pH goes up one unit.


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Acids and Bases

Strength of an acid is simply a measure of

its ability to liberate hydrogen ions

Strength of a base depends on its

generation of hydroxyl ions


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Acid

Substance which furnishes H+ions.

Examples:

HCl

H2SO4

H+

H+

H+

H+H+

H+

H+

H+


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Strong Acids

Hydrochloric HCl

Sulfuric H2SO4

Nitric HNO3

Phosphoric H3PO4 - Moderate weak

Carbonic H2CO3 - Weak acid


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Base

Substance which furnishes OH-ions.

Examples:

NaOH

Ca(OH)2

OH-

OH

-

OH- OH-

OH-

OH-

OH-


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Strong Bases

Sodium Hydroxide NaOH

Potassium Hydroxide KOH

Calcium Hydroxide Ca(OH)2


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Salt

Product of the reaction of an acid and

a base.

Examples:

NaCl

CaCO3

OH-

OH-OH-

OH-OH-

OH-

H+

H+

H+H+

H+

H+

H+

H+


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ACID + BASE

HCl + NaOH

H2CO

3 + Ca(OH)

2

SALT + WATER

NaCl + H2O

CaCO3 + 2H

2O


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Buffer Action

The ability of the salt of a weak acid

to tie up hydrogen ions in the form ofmolecules of the weak acid and

the ability of the salt of a weak base

to tie up hydroxyl ions as molecules of

the weak base.


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Example:Carbonate / Bicarbonate Buffer

Adding acid just changes CO32-HCO3

- ;

the potential for HCO3-

to give up its proton determines pH

O

OC

O

O

HHO

H

HO

OC

OH

CO32- HCO3

-

Both Exist !


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When an ionicsubstance goes into

solution, it forms an

electrolyte. Cl-

Cl-

Cl-

Na+

Na+

Na+

S l bili


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Solubility as aFunction of pH

For most M-I products, as the pHincreases, the solubility increases.

Two exceptions are Ca(OH)2and CaCl2

Solubility

pH


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Solubility

An increase in temperature generallyincreases the solubility of a solid-in-

liquid and also a liquid-in-liquid

Gases become less soluble at highertemperatures, but more soluble athigher pressures


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Titrating

Using a standard solution of known

concentration and volume to determine

the concentration of an unknown

sample of known volume


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Normality

A solution that contains 1 gram equivalent ofa substance per liter of solution

Example:

One normal HCl is 36.5 grams per liter of solution.One normal H2SO4is 49 grams per liter of solution,

because H2SO4has TWO protons


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Indicator

A substance having the unique

property of changing color when the

target ion concentration of the solution

reaches a certain value.


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Alkalinity

The measurement of:

Hydroxides

Carbonates Bicarbonates

Occasionally: Borates

Phosphates

Sulfides


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Pf Test for Alkalinity

2OH- + CO3= + HCO3

- + 2H+

OH- + 2HCO3- + H2O

phenolphthalein


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Mf Test for Alkalinity

HCO3- + 2H+ H2CO3 + H2Omethyl orange


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Pm Test for Alkalinity

OH- + CO3= + Ca(OH)2 + 2H+

H2O + 2HCO3- + 2OH- + Ca++

phenolphthalein(a solid)


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Double Displacement

These are reactions where the metal atoms

exchange places.

Example:

NaCl + AgNO3

AgCl + NaNO3

Sodium + Silver Silver + SodiumChloride Nitrate Chloride Nitrate

Chl id D t i ti


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Chloride Determination(mg/l Cl-)

Cl- + AgNO3 AgCl + NO3-potassium

chromate


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Total Hardness

2(X)H2 + Ca++ + Mg++

(X) Ca + (X) Mg + 4H+

bufferCal Magite

St d d V t ( )


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Standard Versenate (EDTA)C10H14N2O8Na2

For simplicity,

EDTA will be referred to as (X) H2


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Titration for Calcium

Ca++ + Mg++ + OH- + Calcon + EDTA

Mg(OH)2 + EDTA (Ca)


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Other Available Titrations

K+ SO3= CrO4

=

Ca++ SO4= PO4

=

NO2

- S= ZnCO3

NO3- CO3

=


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SUMMARY:

Products

Cations

Ions

Solubility

Reactions

Alkalinity Vs pH

Hydroxyls Carbonates

Bicarbonates

Documents

3 Chemistry