LECTURE 1 COLLOIDS AND COLLOIDAL DISPERSION
COLLOIDS AND COLLOIDAL DISPERSIONColloids Molecules can cluster together to form particles of mater whose over all size is larger than the size of atom or molecules in aqueous solution. In general the normal solution are homogenous mixture of solute and solvent molecule. The size range of atoms or molecules is ordinary solution is 0.05-0.25 nanometer. Some time attraction between molecules forms cluster their size rang (1-100nm.). So matter containing particles of this size called (colloid). A uniform dispersion of a colloid in water called (a colloidal dispersion) which appear cloudily.
The colloid in acolloidal dispersion called dispered substance, the matter in which the colloid dispersed called dispersing substance). The dispersed and dispersing substance can in (9) nine different way to form colloidal dispersion, only 8 of these 9 combination are known because A mixture of 2 gases can't be colloidal dispersion because the particles of agas are individual molecules and when the molecules form cluster, the gas changed to a liquid. Many compounds of high m.wt is living system form colloidal dispersion rather than the solution in water like starch and protein.
Question If colloidals are clusters of molecules why don't the clusters increase in size until they get large enough to settle out.? Answer All particles have most stable colloidal dispersion have the same electrical charge, these charge can be caused by adsorption of ions to the surface of the particles so the particle's repel each other and can't form particles large enough to settle out.
Other colloids are stabilized in water by the a ction of a third substance called amulsifying agent (e.g) (mixture of oil+water), oil is immisible with water, if we added emulsifying agent) (soap) to the mixture, the oil is emulsified by the soap. The soap break up the oil into small drops, the soap molecule form anegativly charge layer on the surface of each oil drop, this cause the oil's drop to repel each other, and they disperse through out the water. (Bile salt) another example of emulsifying agent in living system. These salts break up the Fat's we eat in to small globules that can be more effectively digested. The fluid of living system are a complex mixture of colloids & dissolved and molecules the behaviour of these fluid in the body is vital to life. Apparticlary important property of these fluids is dialysis which is similar to osmosis.
DILYSIS IN LIVING SYSTEM
Osmotic membrain allow water molecules, to pass through it but not solute particles membrances that allow small molecules & ions to pass while holding backs large moledes and colloidal particles called (dialyzing membrain). Plasma membraine are example of such membrain. The selective passage of small molecules and ions in either direction by dialyzing membrane called dialysis. The kidney is an example in living system that use dialysis to maintain the solute of electrolyte balance of blood, dialysis differs from osmosis in that osmotic membraines allow only solvent molecules to pass. The main purpose of the kidney is to cleans the blood by removing the waste product of metabdisim and control the conc of electrolyte. The kidney does this job very efficiently aproximatly 180L of blLECTURE 2 BUFFERS
BUFFER CAPACITYA buffer solution has limited ability to react with acids and bases without changing it is pH, a solution acts as a buffer because it contains both members of conjugate acid-base pair Removal at one of these two by either chemical or physical process destroy the buffer action of the solution example: if enough strong acid is added to an acetic buffer solution all at once or little by little to react with all the acetate ion, the solution losses it is ability to act as a buffer thus continued addition of strong a cads or bases to a buffer solution losing it is ability to act as a buffer blood has a wide capacity as a buffer, that is why it's consider a best Buffer.
ACID-BASE BALANCE IN THE BLOOD
The reaction of bicarbonate & carbonate salt with an acids and Bases are important for controlling:The amount of CO2 in the bodyThe acidity of the blood. Bicarbonate & Carbonate salt are derived from H2CO3 as H2CO3 + NaOH NaHCO3 + H2ONaHCO3 + NaOH Na2CO3 + H2O excessThese two reactions are the way that excess base is neutralized in the body.Carbonic acid is unstable in water as in equationH2CO3 H2O + CO2H2CO3 and H2O & CO2 an in equilibrium in water.Carbonic acid and Bicarbonate (H2CO3 and HCO3-) is a conjugate acid base pair act as a buffer. H2CO3 + H2O H3O+ + HCO3- A conjugate acid-Base-pair A carbonic acid H2CO3 is formed by dissolving CO2 in aqueous body fluids, it is a weak acid that ionized to HCO3- as in equation CO2 + H2O H2CO3 HCO3- + H+ 1.2meq/l 24meq/l Normally in the body fluid such as blood, the a mount of bicarbonate is 24meq./l and the amount of carbonic acid is 1.2meq/l. HCO3-If the ratio of ــــــــــــــــــــ is 20 ( the pH of blood will be (7.3 – 7.4)) H2CO3 HCO3- If the ratio of ـــــــــــــــــــــــــــــless than 20 say 16 (the pH of blood become more acidic say (7.0) ) H2CO3
This phenomenon called acidemia & the physiological process called acidosis. HCO3-If the ratio of ـــــــــــــــــــــmore than 20 say 26 the (pH of blood become H2CO3more alkali more than 7.4 say 7.8), this phenomenon called alkalemia & the physiological process called Alkalosis, death some time occurs if the pH of a blood is more acidic than 6.8 or more basic than 7.8.Previously we say that all buffer solution have limited ability to with stand any addition strong acid or base with out changing their pH.(buffer capacity)
The buffer in the body differs from those in the laboratory. The body can replenish components of buffer solution as they are used up or can remove from the body any excess component. Consider a patient who has an illness that causes an increase in conc. Of acidic product acidosis the amount of carbonic acid increase & the amount of CO2 formed from decomposion of H2CO3 increase also this causes decrease in the ratio (HCO3-/H2CO3), to loss the excess of CO2 deeper and faster berthing called hyperventilation occur, this causes decreases in the acidity of blood because CO2 formed is lost through the lung. If this process is not enough to return the pH of blood to the normal value, the kidney can help by releasing more carbonate ion in blood and removing hydrogen ions. In this way the body tries to return the ratio HCO3-/H2CO3 to 20 and maintain the acid base balance in body, but if the patient have decrease in H2CO3 & in crease in concentration of basic ion, (Alkalosis) the lung and kidney work quickly to remove any excess of basic product. To prevent this state the CO2 conserve & product more carbonic acid, loss of CO2 through the lung is minimize by slower and shallow breathing called (hypoventilation) at this time bicarbonate ion are removed & H+ is added to blood so the body return to the ratio 20 & the pH value at blood remain constant (7.3-7.4).
Lecture 3 Radio activity and nuclear chemistry
RADIO ACTIVITY AND NUCLEAR CHEMISTRYRadio activity: is a term given to describe the emission of radiation from samples (atoms) of certain elements. The elements which have isotopes some are stable and others unstable, the nuclei of unstable isotopes undergo nuclear reaction (decay) which cause new nucleus and energy. The new nucleus either stable or unstable, the unstable decay and give a stable nucleus.
Types of Radiation: Rutherford discovered three different types of radiation, when he put a piece of radio active substance in electric field:1- α-ray (heavy particles) +ve (proton).2- β-ray (light particles) –ve (electron).3- γ-ray (not affected) not charged.
- Alpha emission (α-ray particle): It consist of a stream of positively charged nuclei of He++ atoms called alpha particles.Its common for atoms have atomic mass more than 209, and atomic no. greater than 82 - it reduced the no. of {p} by – 2- and the no. of {n} by – 2 – {24He}. This type of radiation travel with a speed about one-tenth the speed of light and have very slight penetrating power as a result do little damage to internal organs, because they can not penetrating the skin but if substance that emit α – ray gets inside the body by swallowed or inhaled, the α-par. Can then damage internal organs.
Ex.:- 23892U 23490Th +42He 21084Po 20682Pb +42He- β –emission (β –ray particles):- It consist of a stream of electron or β-particles.The no. of neutrons (n) is decreased by – 1 – and the no. of protons (p) is increased by – 1 - , so the ratio of n/p is decreased, but the mass no. is not changed β-emission travel much faster than (α) can penetrate the skin and causes the skin to appear burned.
This type of rad. traveled as fast as light and have intermediate penetrating power. During β-decay one of neutron changed into proton (stay in nuclei) and electron (emitted) which lead to increase in atomic no. but mass no. not change. Ex.:- 8235Br β-decay 8236Kr + 0-1e 146C β-decay 147N + 0-1e 2712Mg β-decay 2713Al + 0-1e
- γ–emission:- Its not a particle but a form of energy similar to light waves or x-ray. This rad. Has high energy and occurs along with α & β emission and can penetrate deep in the body and cause serious damage to the cells. This kind has a higher penetrating power, it can be stopped by block of lead, Ex.:- 24094Pu 23692U + 42He + γ 22688Ra 22286Rn + 42He + γ There are two types of radiation less common but still important. 1- neutron 2-positron emission (+ve electron) 0+1e.
Positron emission: means ejection of +ve electron from the nucleus, it has the same mass as an electron with opposite charge (01e). It arises from the conversion of a nuclear proton into neutron, as a result a decrease by – 1 – in no. of proton and increase by one in no. of neutron, but no change in mass no. occur Ex.:- 3819K 3818Ar + 01e 158O 157N + 01e 2312Mg 2311Na + 01e
EFFECT OF RADIATION ON THE LIVING SYSTEM
Ionizing radiation: Radiation from radio active isotop which can ionize the matter. The effect of radiation on living system causes damage to the cells. When the living molecules are affected such as RNA or DNA, this damage will happen by two ways 1-direct effect. when the radiation changes the structure or break down the living macromolecules which will cause a damage of the living cells: x+ + y – (Two ionic parts) DNA or RNA hט radiation x . + y . ( Two or more free radicals )2- Indirect effect:- When the radiation break down the non living molecules which can be replaced or substituted or reformed again. In this case no damage will happen for ex: H2O hט OH - + H+ or: H2O hט H. +OH.But if these ions or free radicals hits the living molecules, living cell will be affected or damaged. By the high energy ions or free radicals or others. if the DNA destroyed, the cell will not divide and it will be die. But if DNA is damage it will cause abnormal division to produce new cells with altered DNA
Such cells will not be under control of the body called cancer cells which grow and divide under fission and destroying the normal cells. Its clear that exposure to radiation is dangerous? According to one theory called 1) Threshold theory no damage occurs below a certain level of radiation. Opposed to this is the 2) Linear theory according to this the risk of damage is proportional to exposure even down to very low levels of radiation. The radiation can not be detected by human body because we can not feel, smell or see ionized radiation but we have methods to detect this radiation. 1- Geiger counter. 2- Scintillation counter. 3- Photographic method. Each person wears a badge containing a piece of film.
LECTURE 4 NUCLEAR REACTION ( TRANSMUTATION)
Nuclear reaction: (Nuclear transmutation) The theory is that atoms change from one kind to another wither in nature or lab. by means of bombardment reaction, when this change occur the nucleus of an isotopes emits α or β particles. So the nucleus gain or loss positive charge and its atomic no. is changed.Ex.:- C14 can be produced in lab. By bombarding nitrogen with neutron 10n + 147N 146C + 11HC14 is a good β emitter, it can be placed in biological organism and can be traced in lab. as it travels in living system. 146C 147N + 0-1e
Bombardment reaction:- A reaction occurs when particles of atomic or subatomic size strike atoms of an element and change them into another:Ex.: α –particle and Beryllium 94Be + 42He 126C + 10n bombardment particle Nuclear transmutation produced in lab. by bombarding nitrogen gas (N2)with 42He nucleus. As 147N+ 42He 189FHighly unstable nucleus is R- a atom and rapidly decay to form 17O 189F 178O + 11H
1- It tells us how long a sample of isotopes will exist: Ex.:- 137N (t1/2) = 10min if we have 1gm of 137N how long will be after 50min. 1gm 10min 0.5gm 10min 0.25gm 10min 0.125gm 10min 0.0625 10min 0.03105 10min - - - - - 137N t1/2 10min 136C + 01e
2- Half life tells us about the stability of the isotopes if t1/2 large (high) isotopes is stability but if t1/2 low (small) isotopes is unstable. 3- Half life of R. a isotopes is independent on the sample size or the amount of material if we have 1kg, 10gm, 1gm it has the same t1/2, so t1/2 are useful in discovery the age of argiological object. Most of the artificially produced radio active isotopes are unstable and have very short t1/2 but natural once have height t1/2 (stable).
Radiation dosage: radiation causes damage to all living system, the degree of damage is related directly to the dose of radiation received.There are different basic units used to describe the activity of radio active material.1. Curie and Becquerel: (symbol ci) This unit is a measure of a no. of nuclei that decay per sec. its independent on the size of radio active material one curic represent a large amount of radio activity so use. Pci = 10-12 ci, μci=10-6, mci=10-3 The SI unit of radio activity is the Becqueral βq 1 curie = 3.7 x 1010 Becquerel
Equal no. of ci of radiation given of by different isotopes do not produce the same biological effect so we use another unit to assess biological damage like (Rad). 2. Rad {Radiation absorbed dose} (D) it’s a unit that express the amount of energy absorbed by irradiated tissue.One rad = 2.4x10-3 cal of energy absorbed by 1kg of tissue. Its very small unit converted to heat, this energy would raise the temp of tissue.
The SI unit of absorbed dose is the gray (Gy) defined as: one joule of energy absorbed per 1 kg of tissue. 100 rad = one gray The energy absorbed by living tissue is not the only factor that contributes to the biological effects (hazards) of radiation. For this reason a dose of 1 rad from one source is not necessary equal to a dose of one rad from another. So we use another unit which takes all these differences like (Rem).
3. Rem= 1 Rad x RBE RBE: factor (relative biological equivalent) no. of Rem= no. of rad x RBE. The factor RBE takes into account the differences in biological damage caused by different kind of ionizing radiation of the same energy. For ex:- RBE of an alpha particle is 10 times that of beta particle. This mean that α-par released in tissue caused damage 10 times that of β-particles of the same energy.The rem is the more accurate measure of biological damage caused by different ionizing radiation.
So its used to describe doses of radio activity.To determine how much radiation is dangerous to human by using LD50 values:-LD50 : Lethal dose valueLD50 value: Ionizing radiation dose at which injury to human begins is unknown. Its better to express the short term exposure to radiation that is fatal to various form life this is expressed as 30 days LD50 value which is defined as the dose in rem that is fatal to 50% of population within 30 days. LD50 value for human is 500 rem LD50 value for mammals is between 250 – 1000 rem
Lecture 5 Medical uses of Radio active isotopes
Medical uses of Radio active isotopes: Radiation from radio active isotopes is used in medicine to treat cancer, some of radio active isotopes are:1. Cobalt – 60 – its symbol 6027C, its β&γ emission, its widely used as external source of radiation for cancer therapy with t1/2 5.3 years. 2. Iodine – 131 – 13153I, its β & γ emission, its used in treatment of thyroid gland cancer with ty2:8 days.3. Iodine – 123 – 12353I: its symbol, its β – emission, its used in treatment of thyroid cancer with ty2 13.3hr.
4. Phosphorous – 32 – 3215P, its β emission, with ty2 143days used in treatment of leukemia, also in detection of skin cancer and the brain surgery. 5. Sodium 24: 2411Na, its β & γ emission with ty2: 15.0 hr, its used in checking the proper function of circulating system. 6. Iron – 59 – 5926Fe, its β & γ emission with ty2: 45.6 days. Its used in determination of red blood cell formation and life time.7. Technetium – 99 - 9943 Tc, its β-emission with ty2: 6.1 hr. Its used in scanning of brain, kidney and lungs.
Radio active isotopes used in human must be chosen carefully:- First: the half life must be long enough to do its job (to destroy the abnormal cells).Second: no isotopes that emits α- particles are used because α-particle are large and cause damage to all tissues and organs. Nuclear reaction and energy:1/ Nuclear fission: when nuclei of several isotops like 235u, 236u, 244Pu are bombarded with neutrons, they undergo nuclear fission to form smaller, more stable nucleus,
Example:
10n + 23592u 23692u 9436Kr + 13956Ba+310n + energy unstable stable nucleus+
9436Kr
energy
13956Ba
10n
10n
10n
unstable nucleus
This n.f produce great amount of energy E.x: when one Kg of 235u is fissional, it produce amount of energy equals 20,000 tons of T.N.T. 2/ Nuclear fusion reaction:- This reaction allows us to obtain energy without forming dangerous radioactive products involve fusing two or more nuclei to make a heavier nucleus:- Ex.:- Deuterium 21H + 21H 42H In this reaction two nuclei of deuterium (stable isotopes of Hydrogen) are forced together to form a helium nucleus, which is also stable.
This reaction needed temp at least 10,000,000ْC to provide the energy to force the two positive nuclei close enough to fuse. This fusion reaction occurs in two places 1- The sun, whose heat and light are produced by fusion reaction. 2- Hydrogen bomb.
LECTURE 6 ENVIRONMENT POLLUTION
ENVIROMENT POLLUTIONEnvironment pollution:-May be defined as the contamination of air, water, food in such manner as to cause real or potential harm to human health or well-being or to damage the non-human nature. Basically pollution can be classified to: Air pollution Water pollution Noise pollution Solid waste Radio active waste
AIR POLLUTION
Comes from increase the population in the world increase the amount of power power plant (factories) automobiles (trucks, Buses, Personal car, aircraft) The major source of air pollutant comes from the non stoichiometric combustion, dissociation of Nitrogen oxides and impurities in the fuel of air.The emission of concern are: carbon monoxide CO oxides of Nitrogen NO hydro carbon HC photo chemical smag sulfur oxides SO lead and phosphorous solids particles
1- Carbon Monoxides CO:- is a product of in complete combustion of hydrocarbon fuel (CnHn). Most of CO comes from the exhaust of vehicles, CO is colorless, odorless.O2 + HB HBO2 + CO HBCO Stable
2- Hydro Carbon H-C Comes from exhuse gases, and will be different for each gasoline depend on the original fuel. HC emission act as irritants and odorant, all H-C except CH4 it may reach with atmosphere to form photochemical smog some of H-C when get into atmosphere act as carcinogenic
3-Oxides of Nitrogen (NO):- Exhaust gases contion NO in most ofit's constituent and trace amount of NO2 and other nitrogen-oxygen combination NO2 is a very undesirable emission, especially released of NO react with atmosphere to form (ozone,O3)and is one of the major causes of photochemical smog, high temp produce (NO) which is then oxidized further to form NO2 N2 + O2 2NONO + H2 O NO2 + H2
4-Phatochemical smogis one of the primary causes of photochemical reaction of automobile exhaust and atmosphere air in the presence of sunlight NO2 + Energy of sunlight NO + O + Smog O + O2 O3 (ozone)Ground level ozone is harmful to lung and biological tissue, also it's harm tress and harm full to tress & other vegetable plant.
5- Sulfur oxides Many fuel used in engine contain sulfure in it's exhaust which contribute in acid rain formation, at high temp, sulfur combines with hydrogen to form H2S and with oxygen to form SO2H2 + S H2SO2 + S SO2Then 2SO2 + O2 2SO3SO3 combine with water vapour in the atmosphere to form sulfuric acid (H2SO4)and sulfurous acid (H2SO4) and sulfurous acid (H2SO3 ) which are ingredients in acid rain SO3 + H2O H2SO4SO2 + H2O H2SO3
6-Lead and phosphorans: Lead was a major gasoline additive (tetraethyl lead) was effectively used to increase the gasoline, octane number which allowed higher compression ratio and more efficient engine. However the resulting lead engine exhaust was highly poisonous pollutant, small amount of phosphorous are emitted also, these comes from impurities in the air and small amount found in some fuel blends and lubrication oil.
7-Solid particles (Particulates) Small solid particles and liquid droplets collectively called (Particulates) are present in air in great number, and at times constitute a serious pollution problem, particulates are some times classified as viable (capable of living), or non viable. Some examples of viable particulates are bacteria, fungi, and spores. Non viable particulates, include such substances as organic compounds, metals, dust, and sea salt. Particulate air pollution warrant serious attention for several reasons: Many particulates affect respiratory system, more effectively than air pollutant. Particulates increase atmospheric turbidity and reduce visibility. Particulates are formed within the atmosphere from some gaseous pollutant. Some particulates behave as synergistic and enhance the toxic effects of other pollutants.
HEALTH EFFECTS
The respiratory system The major target of air pollutants is the respiratory system. Air and entrained pollutants enter the body through the throat and nasal cavities and pass to the lungs through the trachea and bronchia. Entrained pollutant particles can be prevented from entering the lung by the action of ting hairs called (cilia) that sweep mucus out through the throat and nose. The bronchial cilia can be paralyzed by inhaled smoke enhancing the synergistic effect between smoking and air pollution. In the lungs, the air movies through bronchial tubes to the alveoli, small air sacka in which oxygen from the lungs is transferred to the blood.EFFECT OF CARBON MONOXIDE
The effect of CO inhalation on human health is directly proportional to the quantity of CO bound to hemoglobin. Oxygen is transported in the blood as oxyhemoglubin (HbO2 ), it is semi stable compound in which O2 is weakly bound to Fe+2 in hemoglobin in red blood cells. The O2 is removed for cell respiration and the regenerated hemoglobin is available for more oxygen transport. CO reduces the oxygen-carring capacity of the blood by combining with hemoglobin and forming carboxyhemoglubin (HbCO) which is stable.Hemoglobin that is tied up as (HbCO) can be regenerated and is not available for oxygen transport for the life of that particular red blood cell. In this way (CO) effectively poisens the hemoglobin oxygen transport system. Hemoglobin has a greater affinity for (CO) than for molecular oxygen.
EFFECT OF SULFER OXIDE
The cilia that protect the respiratory system by sweeping out particles are effected by gaseous air contamination. The predominant effect on the cilia of smokers is paralysis from the constituents of tobacco smoke. Sulfur dioxide also affect ciliar behaviour. Thus SO2 affects the protection mechanism of the respiratory tract in addition to contracting the bronchia.EFFECT OF NO
NO2 is a pulmonary irritant. High concentration of NO2 can produce pulmonary edema; an abnormally high accumulation of fluid in the lung tissue
EFFECT OF OZONE
Ozone and photo chemical oxidants are highly irritating, oxidizing gases, concentration of few parts million can produce pulmonary congestion, edema, and pulmonary heamorrage. A one hour exposure of human subject to 25g/m3 can decrease effective lung volume and decrease maxium breathing capacity. Symptoms of ozone and oxidixant exposure are a dry throat followed by headache, disorientation and altered breathing patterns.lab 1 aldehyde and ketone
Ex:- acetone also call carbonyl group test used to distinguish ald. and ketone Tollen,s test is used to identify the aldehyde . tollen,s reagent 1-(( silver nitrate AgNO3 )) 2-sodium hydroxide (( NaOH )) 3-ammonia NH3silver nitrate sodium hydroxide
Black ppt. silveroxidesodium nitrate
Silver ammonia complex Tollen ,s reagentprocedure In two clean test tube put 1- 10 drop of tollen reagent 2-then added to the first one 5 drops of acetaldehyde then added to the second one 5 drops of acetone wait 1 min , silver mirror deposited on the side the test tube in aldehyde (because aldehyde contain H atom ) and no reaction in the 2nd tube because ketone is not contain H atom Fehling test:Fehling solution consist of :- 1- fehling solution one : CuSO4 cupper sulfate-blue colour 2- fehling solution two : sodium –pottasium tartarate principle of fehling test aldehyde act as reducing agent it can reduce the deep blue colour of fehling solution in to red ppt. of cuprous oxide
Ald.
Cupric ionCarboxyl ion
red ppt.. of cuprous oxide
acetone
Cupric ion
procedure in two clean test tube put 1- 5 drop of fehling 2- 15 drop of fehling mixed very well then added to the first one 10 drops acetaldehyde and to the second 3 drops acetone mixed very well , then put the tubes in a boiling water bath for 3-5 min, red ppt. appears in the first tube indicate the presence at aldehyde (because it contain H atom ) , In the 2nd no change in colour (remain blue colour ) because it contain ketone (absence of H atom )
Conclusion
Observationtest
Tollen,s test
Silver mirror
aldehyde acetaldehyde
No reaction
ketone acetone
Fehling test
Red ppt.
aldehyde acetaldehyde
blue colour (no reaction )
ketone acetone
lab 2 Analysis of group and test of the ions within the group
Soluble complex
filtrated ppt Ag+1 black ppt. to identify Ag indicate the added 1 drop of phenonaphthalene solution presence Hg2+2 then added (4M)HCl drop by drop until white ppt. appear indicate the presence for Ag+1
Test
ObservationConclusion
Silver
White ppt.
Indicate the presence of Ag+ ion
Lead
Yellow ppt
Indicate the presence of Pb+2 ion
Mercurous
Black ppt
Indicate the presence of Hg2+2 ion
lab 3 Determination of PH
Determination of PhDetermination of pH = means determination the power of H+ in the solution pH define as = the negative Log of hydrogen ion conc. pH = - Log(H+) Table -1-pH of some fluid .1- blood plasma = 7.42-pancreatic juice = 83-gastric juice = 1.2 – 34-urine = 5 – 85-pepsine = 2 The fluid of all living organism contain conjugated acid or base which act as buffer In determination of pH we should know the following . 1- indicator .means an organic dyes which change their colour with change of the pH
pH of some indicators
pH1
phenolphthalein
8.8-10
2
Methyl orange
2.9-4.6
3
Thymol blue. (acid)
1.2-2.8
4
Thymol blue. (base)
8-8.4
5
Phenol red
6.8-8.4
6
Bromophenol blue .
2.8-4.4
7
Bromothymol blue
6-7.6
1-universal indicator paper2-universal indicator solution method used for determination for determined pH value .1-by litmus paper . only for acid solution or basic solution .2-by universal indicator . ( paper solution )3-colorimetric method by ( Lovibond method ) .4-Electro metric method by ( pH – meter ) **By universal indicator paper and solution procedure ;1-clean 5 test tube put 10 drops solution 1,2,3,4,5 2-cut small piece of universal indicator paper then put one of solution to the end of the paper and allow to the dry for 1min ,then compare the color on the chart . record the result .3-add to each tube 1 drop of universal indicator mixed and compare colour with the colour on the chart then record the result .
No. of solution
pH univ. (paper colour )pH univ. solution
1
2
3
4
5
** Electrometric method.Is the best method for determine pH . It depend upon the tension set between two electrode . positive and negative or depend upon the measurement of electrometric force between H+ and OH- in the solution . PH meter consist of :-1-the + ve electrode called (calomel electrode ) is made by .( Hg / HgCl and saturated solution of KCl ) It is called (reference electrode )2-the –ve electrode is glass electrode . which filled with 0.1 N HCl . when there two electrode . placed in the solution a different of potential . develops between the solution inside the electrode and that outside. The value depend upon the conc. of H+ outside the electode because the conc. of H+ inside the electrode remane constant
lab 4 Titrimetric analysis
Titrimetric analysis : Means to find the quantity of substance by using titration Titration : is the process of addition of standard solution of known concentration to another unknown substance until the reaction complete , this can be obtained by using indicator . Standard solution : The reagent exact known concentration used in titration Equivalent point (end point): the point at which amount of the standard solution equivalent to the substance that react during titration . Indicator :- Chemical compound that charge their colour with change the PH Primary standard solution :- High purified chemical compound and stable . Normality : Is the unit to measure the concentration . Of the solution .No. of equivalent of solute N = ……(1) Volume of solution (liter) Or No. of miliequivalent of dissolved solute N = ..…(2) Volume of solution (liter) weight No. of equivalent = ……(3) Equivalent wt weight Ч 1000 No. of miliequivalent = …..(4) Equivalent wt Molecular wt Equivalent wt = No of charge wt wt Ч 1000 N = or N = equivalent Ч V (liter) equivalent Ч V (ml)
Procedure : fill the burette with HCl solution. Measure (5 ml) of unknown solution Na2CO3 . by pipette and put in conical flask. Add one drop of methyl orange indicator yellow colour appear Titrate HCl aqunist Na2CO3 by adding drop by drop till the pink colour appear stopped the titration and calculation .