Review about Analytical Chem.

Solutions

Concentration, calculation , Clinical Applications

Asst.Prof.Dr.Alaa J.Mahrath

Medicinal Chemistry

Biochemistry

College of Medicine Babylon University

Defining a Solution and it’s derivatives

• Solutions: are homogeneous mixtures of substances

composed of at least one solute and one solvent.

• homogeneous mixture: a uniform mixture of only one

phase

• solute: a substance that is dissolved in a solvent (e.g.,

salt, NaCl)

• Solvent: the medium in which a solute is dissolved;

often the liquid component of a solution (e.g., water)

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• The chemical formula

For example,

• NH3(aq) : ammonia gas (solute) dissolved in water (solvent)

• NaCl(aq) : solid sodium chloride (solute) dissolved in water (solvent)

• I2(al) : solid iodine (solute) dissolved in alcohol (solvent)

• C2H5OH(aq) : liquid ethanol (solute) dissolved in water (solvent)

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Properties of Aqueous Solutions

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Compounds can be classified as either electrolytes or nonelectrolytes.

Electrolytes are solutes that form solutions that conduct electricity. At this point we will restrict ourselves to compounds in Aqueous solutions. Compounds are electrolytes if their aqueous

solutions conduct electricity. Compounds are nonelectrolytes if their

aqueous solutions do not conduct electricity.

Question : How to test a solution if Electrolyte or Not?

• Most household aqueous

solutions, such as fruit juices

and cleaning solutions, contain electrolytes. The

conductivity of a solution is

easily tested with a simple

conductivity apparatus (Figure

4) or an ohmmeter. This

evidence also provides a

diagnostic test to determine

the class of a solute

electrolyte or nonelectrolyte. This very broad classification

of compounds into electrolyte

and nonelectrolyte categories .

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• electrolyte: a compound that, in an aqueous solution, conducts electricity.

• nonelectrolyte: a compound that, in an aqueous solution, does not conduct electricity.

• Electrolytes are mostly highly soluble ionic compounds (e.g.,KBr(aq) ),including bases such as ionic hydroxides (e.g., sodium hydroxide, NaOH(aq) ).

• Most molecular compounds (e.g., ethanol, C2H5OH(aq) ) are nonelectrolytes, with the exception of acids. Acids (e.g., nitric acid, HNO3(aq) ) are molecular compounds that, in aqueous solution, conduct electricity.

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Question : Which of the white solids labelled 1, 2, 3, and 4 is calcium chloride,

citric acid, glucose, and calcium hydroxide? Give me your explaination

Question: Which of the solutions labelled 1, 2, 3, and 4 is hydrobromic

acid, which is ammonium sulfate, which is lithium hydroxide, and which is methanol?

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Solution Concentration

• concentration: the quantity of a given solute in a

solution

• dilute: having a relatively small

quantity of solute per unit volume of solution

• concentrated: having a

relatively large quantity of solute per unit volume of solution

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• In General, the concentration, c,

of any solution is expressed by the

ratio :

• concentration = (quantity of

solute/quantity of solution)

• Percentage Concentration :

Many consumer products, such as

vinegar (acetic acid),are conveniently

labeled with their concentration ratios

expressed as percentages (Figure 2).

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Read sample problem 1 in textbook

• A vinegar label listing “5% acetic acid (by volume)”

means that there are 5 mL of pure acetic acid

dissolved in every 100 mL of the vinegar solution.

• This type of concentration is often designated as %

V/V, percentage volume by volume, or percentage

by volume.

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• Another common concentration ratio used for consumer products is “percentage weight by volume” or % W/V.

• For example, a hydrogen peroxide topical solution used as an antiseptic is 3% W/V figure 2.

• This means that 3 g of hydrogen peroxide is in every 100 mL of solution.

• A third concentration ratio is the “percentage weight by weight,”or % W/W:

You have the Solution ….

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Very Low Concentrations

• For very small quantities of solute we choose a concentration unit to give reasonable numbers.

• For example, the concentration of toxic substances in the

environment or of chlorine in a swimming pool is usually

expressed as parts per million ( ppm, 1:106)

• or even smaller ratios, such as parts per billion (ppb, 1:109) or

parts per trillion (ppt, 1:1012).

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Sample Problem 2 : A sterling silver ring has a mass of 12.0 g and contains 11.1 g of pure silver.What is the percentage weight by weight concentration of silver in the metal?

• We can express the parts per million (ppm)

concentration using a variety of units. Choose the one that matches the information given in

the example you are calculating. For aqueous

solutions .

• 1 ppm = 1 g/106 mL

• = 1 g/1000 L

• = 1 mg/L

• = 1 mg/kg

• = 1 µg/g

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• Dissolved oxygen in natural waters is an important

measure of the health of the ecosystem. In a

chemical analysis of 250 mL of water at SATP, 2.2

mg of oxygen was measured.

What is the concentration of oxygen in parts per

million?

• Solved ….

The oxygen concentration is 8.8 ppm.

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Mass Percent (m/m) Concentration • Mass percent (m/m) describes the mass of the

solute in grams for exactly 100 g of solution.

• In the calculation of mass percent (m/m), the

units of mass of the solute and solution must be

the same.

• If the mass of the solute is given as grams, then

the mass of the solution must also be grams.

• The mass of the solution is the sum of the mass of the solute and the mass of the solvent.

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• Example : What is the mass percent of NaOH in a

solution prepared by dissolving 30.0 g of NaOH in

120.0 g of H2O?

• Answer:

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• Volume Percent (v/v)

• Concentration Because the volumes of liquids or gases are easily measured, the concentrations of their solutions are often expressed as volume percent (v/v).

• The units of volume used in the ratio must be the same, for example, both in milliliters or both in liters.

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• A bottle contains 59 mL of lemon extract solution. If

the extract contains 49 mL of alcohol, what is the

volume percent (v/v) of the alcohol in the solution?

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Mass,Volume Percent (m/v) Concentration

• Mass, volume percent (m/v): describes the

mass of the solute in grams for exactly

• 100 mL of solution. In the calculation of

mass/volume percent, the unit of mass of

the solute is grams and the unit of the

solution volume is milliliters.

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• A potassium iodide solution may be used in a diet

that is low in iodine. A KI solution is prepared by

dissolving 5.0 g of KI in enough water to give a final

volume of 250 mL. What is the mass/volume percent

(m/v) of the KI solution?

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Molarity (M) Concentration

• When chemists work with

solutions, they often use molarity

(M), a concentration that states

the number of moles of solute in

exactly 1 L of solution.

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• A topical antibiotic is 1.0% (m/v) clindamycin. How

many grams of clindamycin are in 60. mL of the

1.0% (m/v) solution?

• Solution:

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• Zinc reacts with HCl to produce hydrogen

gas, H2, and ZnCl2. How many liters of a 1.50

M HCl solution completely react with 5.32 g

of zinc?

• Answer :

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Clinical Applications • A patient receives 100. mL of 20.% (m/v) mannitol

solution every hour. a. How many grams of mannitol are

given in 1 h? b. How many grams of mannitol does the

patient receive in 12 h?

• A patient receives 250 mL of a 4.0% (m/v) amino acid

solution twice a day. a. How many grams of amino acids

are in 250 mL of solution? b. How many grams of amino

acids does the patient receive in 1 day?

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Dilution Solution • In chemistry and biology, we often prepare diluted

solutions from more concentrated solutions.

• In a process called dilution, a solvent, usually water,

is added to a solution, which increases the volume.

As a result, the concentration of the solution

decreases.

• In an everyday example, you are making a dilution

when you add three cans of water to a can of

concentrated orange juice.

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• We can write this equality in terms of the

concentration, C, and the volume, V.

• The concentration, C, may be percent

concentration or molarity.

C1V1 = C2V2

Concentrated Diluted solution

solution

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• A doctor orders 1000 mL of a 35.0% (m/v) dextrose

solution. If you have a 50.0% (m/v) dextrose solution,

how many milliliters would you use to prepare 1000.

mL of 35.0% (m/v) dextrose solution?

• Solution :

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Although the addition of solvent increases the volume, the amount of solute does not change; it is the same in the concentrated solution and the diluted solution .

Grams or moles of solute = grams or moles of solute Concentrated solution Diluted solution

Measuring Temperature

• Temperature, the measure of how hot or cold an

object is, is commonly reported either in Fahrenheit

(°F) or Celsius (°C) units .

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converting between the Fahrenheit and Celsius scales is similar to converting between different units of length or volume, but is a bit more complex because two corrections need to be made one to adjust for the difference in degree size and one to adjust for the different zero points. The size correction is made by using the relationship 1 °C = (9/5) °F and 1 °F = (5/9) °C

Temperature Sensitive Materials

• A class of materials called

thermochromic materials change color as their temperature increases and they change from the liquid phase to a semicrystalline ordered state. These liquid crystals can be incorporated into plastics or paints, and can be used to monitor the temperature of the products or packages in which they are incorporated.

• For example, some meat packaging now includes a temperature strip that darkens when the meat is stored above a certain temperature, making the meat unsafe to eat. Hospitals and other medical facilities now routinely use temperature strips that, when placed under the tongue or applied to the forehead, change color to indicate the patients body temperature. There are even clothes that change color based on the air temperature.

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Applications of Solutions

• OUR KIDNEYS PRODUCE URINE, WHICH CARRIES WASTE

products and excess fluid from the body.

• they also reabsorb electrolytes such as potassium

and produce hormones that regulate blood

pressure and calcium blood levels.

• diseases such as diabetes and high blood pressure

can cause a decrease in kidney function.

• Symptoms of kidney malfunction include protein in

the urine, an abnormal level of urea nitrogen in the

blood, frequent urination, and swollen feet.

• if kidney failure occurs, it may be treated with

dialysis or transplantation.

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• Michelle has been suffering from kidney disease because of severe strep throat as a child. When her kidneys stopped functioning, Michelle was placed on dialysis three times a week. as she enters the dialysis unit, her dialysis nurse, amanda, asks Michelle how she is feeling.

• Michelle indicates that she feels tired today and has considerable swelling around her ankles. the dialysis nurse informs her that these side effects occur because of her body’s inability to regulate the amount of water in her cells.

• Amanda explains that the amount of water is regulated by the concentration of electrolytes in her body fluids and the rate at which waste products are removed from her body.

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• Amanda explains that although water is essential for the many chemical reactions that occur in the body, the amount of water can become too high or too low because of various diseases and conditions.

• Because Michelle's kidneys no longer perform dialysis, she cannot regulate the amount of electrolytes or waste in her body fluids. as a result, she has an electrolyte imbalance and a buildup of waste products, so her body is retaining water. Amanda then explains that the dialysis machine does the work of her kidneys to reduce the high levels of electrolytes and waste products.

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• Solutions are everywhere around us. Most of the gases,

liquids, and solids we see are mixtures of at least one

substance dissolved in another. There are different types

of solutions. The air we breathe is a solution that is

primarily oxygen and nitrogen gases. Carbon dioxide

gas dissolved in water makes carbonated drinks. When

we make solutions of coffee or tea, we use hot water to

dissolve substances from coffee beans or tea leaves. The

ocean is also a solution, consisting of many ionic

compounds such as sodium chloride dissolved in water.

In your medicine cabinet, the antiseptic tincture of

iodine is a solution of iodine dissolved in ethanol.

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• Our body fluids contain water and dissolved

substances such as glucose and urea and

electrolytes such as K+, Na+, Cl-, Mg2+, HCO3-, and

HPO42-. Proper amounts of each of these dissolved

substances and water must be maintained in the

body fluids.

• Small changes in electrolyte levels can seriously

disrupt cellular processes and endanger our health.

Solutions can be described by their concentration,

which is the amount of solute in a specific amount

of that solution.

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• These relationships, which include mass % (m/m),

volume % (v/v), mass /volume % (m/v), and molarity

(M), can be used to convert between the amount

of a solute and the quantity of its solution.

• Solutions are also diluted by adding a specific

amount of solvent to a solution. In the processes of

osmosis and dialysis, water, essential nutrients, and

waste products enter and leave the cells of the

body. The kidneys utilize osmosis and dialysis to

regulate the amount of water and electrolytes that

are excreted.

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