Presented by Niamat Ullah

Life Saving son

Solutions are homogeneous mixtures of two or more pure substances.

In a solution, the solute is dispersed uniformly throughout the solvent.

The clinical lab almost always uses solutions. A solution means that something has been dissolved in a liquid. In the clinical laboratory the solvent we measure most of the time is human plasma. The solute is whatever the substance is we want to measure.

Mixtures of substances – the substances in a solution are not in chemical combination with one another.

Dispersed phase - the substance is dissolved (the solute)

The substance in which the solute is dissolved is the solvent.

Solute + Solvent = Solution

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The intermolecular forces between solute and solvent particles must be strong enough to compete with those between solute particles and those between solvent particles.

As a solution forms, the solvent pulls solute particles apart and surrounds, or solvates, them.

If an ionic salt is soluble in water, it is because the ion-dipole interactions are strong enough to overcome the lattice energy of the salt crystal.

UnsaturatedLess than the

maximum amount of solute for that temperature is dissolved in the solvent.

SaturatedSolvent holds as

much solute as is possible at that temperature.

Dissolved solute is in dynamic equilibrium with solid solute particles.

A supersaturated solution is one in which the solution has had different forces applied to it, allowing for a higher concentration of solute in the liquid than would be possible if no forces were applied. The solubility of a solution increases as the temperature is increased. This means that as the temperature rises, more solute can be dissolved. However, as the temperature of the supersaturated solution decreases, maximum saturation decreases again meaning sedimentation and settling will occur. Increased pressure also increases maximum possible saturation and allows for a supersaturated solution.

Chemists use the axiom “like dissolves like”:Polar substances tend to

dissolve in polar solvents.

Nonpolar substances tend to dissolve in nonpolar solvents.

The more similar the intermolecular attractions, the more likely one substance is to be soluble in another.

Glucose (which has hydrogen bonding) is very soluble in water, while cyclohexane (which only has dispersion forces) is not.

Vitamin A is soluble in nonpolar compounds (like fats).

Vitamin C is soluble in water.

In general, the solubility of gases in water increases with increasing mass.

Larger molecules have stronger dispersion forces.

The solubility of liquids and solids does not change appreciably with pressure.

The solubility of a gas in a liquid is directly proportional to its pressure.

In chemistry, the equivalent concentration or normality of a solution is defined as the molar concentration divided by an equivalence factor :

mEq

n chemistry, the molar concentration, is defined as the amount of a constituent (usually measured in moles – hence the name) divided by the volume of the mixture : It is also called molarity, amount-of-substance concentration, amount concentration, substance concentration, or simply concentration.

Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L).

Common prefixes and abbreviations that are added to units of measure:

deci (d) 10-1

centi (c) 10-2

milli (m) 10-3

micro ( μ) 10-6

nano (n) 10-9

pico (p) 10-12

femto (f) 10-15

Example: A common unit of liquid measurement is a deciliter( dl ), or one – tenth of a liter

Combine a prefix with a basic unit results in a statement of a specific length, weight or volume Reporting clinical chemistry results may be in units such as :

mg / dL g / dL mEq / L

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Atomic mass, Molecular weight, and Formula Weights

Moles: 1mole = 6.022 x 1023 (atoms, molecules or formula units)

Equivalents Weights / Liter Equivalent weight is equal to the gram molecular

weight of a substance divided by its valence Valence = the electrical charge of an ion, or the

number of moles that react with 1 Mole H+

Example The MW of calcium = 40 grams Calcium ions carry a +2 electrical charge

( valence = 2 ) Equivalent Weight of calcium = 40 / 2 = 20 gram

equivalent weight

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N= number of grams of soluteGram equivalent weight of solute

1.00 L of solution

Normality (N) N = Molarity (M) x valence Molarity = N / valence M is always < N

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% w/w – percentage weight per weight Most accurate method of expressing concentration

% w/w = gram of solute OR gram of solute per 100.0 g of solution 100.0 g of solution

How many grams of NaOH are needed to make a 25.0% w/w solution using deionized water as the solvent?

25.0% w/w = X g of solute in 100 g of solutionX= 25.0 g NaOH

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% w/v – percentage weight per volume Easiest & most commonly used, very accurate if temperature

controlled.

%w/v= g of solute OR g of solute per 100.0 mL of solution 100 mL of solution

What is the %w/v of a solution that has 15.0 g of NaCl dissolved into a total volume of 100 mL deionized water?

X% w/v = 15.0 g NaCl 100 mL of solution

X= 15.0 %

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% v/v –percentage volume per volume Least accurate, but used when both

substances are liquids Note: volumes of liquids are not necessarily

additive

%v/v= mL of solute OR milliliter of solute per 100 mL of solution

100 mL of solution

How many milliliters of ethanol are needed to make a 75.0% v/v solution using deionized water as the solvent?

75.0% v/v EtOH = X mL EtOH in 100 mL of solution

= 75.0 mL EtOH

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Molarity (M)= moles/liter or mmoles/mL Normality(N) = equivalence/liter or meq/mL Molality(m) = moles/1000g solvent

Density = mass solute /unit volume Specific Gravity = Dsolute/DH20

DH2O = 1.00000 g/mL @ 4oC DH2O = 0.99821 g/mL @ 20oC

Mass % of A = mass of A in solutiontotal mass of solution

100

moles of Atotal moles in solution

XA =

In some applications, one needs the mole fraction of solvent, not solute—make sure you find the quantity you need!

mol of soluteL of solution

M =

volume is temperature dependent, molarity can change with temperature.

mol of solutekg of solvent

m =

Because both moles and mass do not change with temperature, molality (unlike molarity) is not temperature dependent.

Some substances form semi permeable membranes, allowing some smaller particles to pass through, but blocking other larger particles.

In biological systems, most semi permeable membranes allow water to pass through, but solutes are not free to do so.

In osmosis, there is net movement of solvent from the area of higher solvent concentration (lower solute concentration) to the are of lower solvent concentration (higher solute concentration).

If the solute concentration outside the cell is greater than that inside the cell, the solution is hypertonic.

Water will flow out of the cell.

If the solute concentration outside the cell is less than that inside the cell, the solution is hypotonic.

Water will flow into the cell, and hemolysis results.

Suspensions of particles larger than individual ions or molecules, but too small to be settled out by gravity.

Colloidal suspensions can scatter rays of light.

This phenomenon is known as the Tyndall effect.

Some molecules have a polar, hydrophilic (water-loving) end and a nonpolar, hydrophobic (water-hating) end.

A suspension of liquid droplets or fine solid particles in a gas is called an aerosol. In the atmosphere these consist of fine dust and soot particles, and cloud droplets.

suspension: system does not stays stable and settle Examples of Suspensions

Mud or muddy water, is where soil, clay, or silt particles are suspended in water.

Paint Chalk powder suspended in water. Dust particles suspended in air. Algae in water Milk of Magnesia Flour suspended in water, as pictured to the right.

MATTER

Heterogeneous mixture

Is it uniform throughout?

No

Homogeneous

Yes

Can it be separated by physical means?

Pure Substance Homogeneous Mixture (solution)

Can it be decomposed into other substance by a chemical process?

Element Compound

No yes

No yes