General Introduction The chemical solutions are homogeneous mixtures of substances in the same or different states of aggregation. The concentration of a solution is one of its main features. Quite a few properties of solutions depend only on the concentration. Their study is of interest to physics to chemistry. Examples of solutions include: salt water, oxygen and nitrogen from the air, carbon dioxide in soft drinks and all properties: color, flavor, density, melting point and boiling depend on the quantities of different substances put.
The substance present in greater quantity is often called solvent, and the lowest amount is called the solute and the dissolved substance.
The solute can be a gas, liquid or solid, and the solvent may also be a gas, liquid or solid. The sparkling water is an example of a gas (carbon dioxide) dissolved in a liquid (water).
gas mixtures are solutions. True solutions differ from colloidal solutions and suspensions in which the solute particles are molecular size and are scattered among the solvent molecules. Some metals are
others when they are soluble in the liquid state and solidify maintaining the mixture of atoms. If that mix the two metals can solidify, then be a solid solution.
The study of the different aggregation states of matter usually refers, for simplicity, to a laboratory situation, admitting that the substances in question are pure, ie, consist of a single type of elemental constituents, whether atoms molecules, or ion pairs. State changes when they occur, only affect your ordination or aggregation.
However, in nature, matter occurs most often in a mixture of pure substances. The solutions are a particular type of mixtures. The air in the atmosphere or sea water are examples of solutions. The fact that most of the chemical processes taking place in solution makes the study of solutions an important section of physical chemistry.
This paper offers a general introduction it talks a bit about the basics you need to know in order to delve into the topic of the solutions, this talk about what are the solutions, which is a solvent and a solute, it also explains about what makes it different from a colloid solution or suspension.
This work has several issues which are solubility properties physical solutions, solution concentration, solid solutions, liquid and gas, the effect of temperature and pressure on solubility of solids and gases.
Solubility Solubility is the ability of a substance dissolved in another, the solubility of a solute is the amount of this.
Some liquids, like water and alcohol, can dissolve each other in any proportion. In a sugar solution in water, it can happen that, if he continues to add more sugar, they reach a point where no more will dissolve, then the solution is saturated.
The solubility of a compound in a solvent and a specific given temperature and pressure is defined as the maximum amount of the compound can be dissolved in the solution. In most substances, solubility increases with increasing temperature of the solvent. In the case of substances such as gases or organic salts of calcium, the solubility in a liquid increases as temperature decreases.
In general, the higher solubility occurs in solutions that molecules have a structure similar to the solvent.
The solubility of various substances, some of which are poorly soluble or insoluble. Table salt, sugar and vinegar are highly soluble in water, but almost no sodium bicarbonate dissolves.
physical properties of the solutions
When you add a solute to a solvent, altered physical properties of the solvent. By increasing the amount of solute raises the boiling point and lower the freezing point. Thus, to prevent freezing of water used in cooling of automobile engines, add antifreeze (solute). But when adding a solute lowers the vapor pressure of the solvent.
Another remarkable property of a solution is its ability to exert osmotic pressure. If we separate two solutions of different concentrations in a semipermeable membrane (a membrane that allows passage of solvent molecules, but prevents the passage of solute), solvent molecules will move from the less concentrated solution to the solution of higher concentration, making the latter more dilute. These are some of the features of the solutions:
• The solute particles are smaller than in other kinds of mixtures.
• Present a single phase, ie homogeneous.
• If left to stand for a while, the phases are not separated or observed sedimentation, ie the particles settle to the bottom of the container.
• They are completely transparent, ie, allow the passage of light.
• All components or phases can not be separated Concentration by filtration
solution concentration of a solution gives the number of molecules have to have the solute of a substance and the number of molecules that have the rest of the substance.
There are different ways to say the concentration of a solution, but the two most used are: grams per liter (g / l) and molarity (M). Grams per liter
indicate the mass of solute, in grams, contained in a given volume of solution in liters. Thus, a solution of sodium chloride at a concentration of 40 g / l containing 40 g sodium chloride per liter of solution.
The molarity is defined as the amount of substance of solute, in moles, contained in a certain volume of solution in liters, ie M = n / V.
The number of moles of solute is equal to the ratio between the mass of solute and the mass of one mole (molar mass) of solute.
For example, to find the molarity of a solution prepared by dissolving 70 g sodium chloride (NaCl) up to 2 liters of solution, calculate the number of moles of NaCl, as the molar mass of sodium chloride is the sum of the atomic masses of its components, ie, 23 + 35.5 = 58.5 g / mol, the number of moles will be 70/58, 5 = 1.2 and therefore M = 1, 2 / 2 = 0.6 M (0.6 molar).
Milliosmoles per liter concentration
The phenomenon of osmosis occurs when a solution is separated from its solvent by a semipermeable membrane. Osmosis is the diffusion of solvent through the membrane from the lowest to the highest concentration. The osmotic pressure is the pressure to be applied on the solution of higher concentration to prevent the passage of the solvent (osmosis) through the membrane.
Biological membranes have different permeabilities and are said to be semipermeable, that is permeable to solvent molecules or small molecules, but do not allow free passage of all molecules in solution.
The osmol is a biological unit that is used for solutions having osmotic activity. The osmol turns out to be a very large unit for biological phenomena, most commonly used milliosmole subunit (mosmol) that is more representative; To calculate mosmol need to know if the solute ionized or not, the ionization increases the number of particles in solution, when dissolved 180 mg of glucose to one liter have 1 mmol of glucose, as this substance does not ionize also have 1 mosmol of glucose, when dissolved 58.5 mg Sodium chloride, salt that ionizes giving two ions ( Na + and Cl-), then 58.5mg equals 1 mmol of salt but equal 2 mosmol. The osmotic pressure depends on the number of particles rather than its charge or its mass, the same osmotic force exerted by a large molecule like a protein with a molecular weight of many thousands and thousands of loads as the hemoglobin molecule or an ion of sodium or chlorine.
Most body fluids has an osmotic pressure that is consistent with a solution of sodium chloride 0.9% and it is said that a solution is isosmotic with physiological fluids.
The isotonic solutions with respect to each other exert the same osmotic pressure, or containing the same concentration of osmotically active particles. When speaking of isotonic solutions in the laboratory typically involve solutions having the same osmotic pressure of blood plasma, which is approximately 300 milliosmoles / liter. Physiological solutions of concentration less than 300 hypotonic and if their concentration is higher are called hypertonic. A solution is isotonic with respect to a living cell when it happens gain or net loss of water in the cell, nor is no change of the cell when in contact with the solution.
If we consider that the osmolar concentration of a solution containing a mixture of electrolytes and neutral molecules is equal to the sum of the individual osmolar concentrations of all components, making the concentration of solutes found in serum osmolarity. A simple formula that offers a good clinical utility is:
Osmolarity = 2 (Na + mmol / l) + glucose mmol / l + NUS mmol / L also
Osmolarity = 2 (Na + meq / l) + Glucose mg / dl / 18 + NUS mgl / dll / 2.8
where the factor 2 is due to consider the ions associated with Na + (Cl-and HCO3-), 1 mosmol of glucose equivalent to 180 mg / l = 18 mg / dl, 1 mosmol of urea nitrogen (BUN) is equivalent to 28 mg / l = 2.8 mg / dl, corresponding to the molecular mass of two atoms of nitrogen in urea.
electrolytes Na +, HCO3-and Cl-contribute more than 92% of the osmolarity serum, the remaining 8% is glucose, proteins and urea. Classification
solutions
their condition ITS SOLID SOLUTION CONCENTRATION
unsaturated, is one in which the dispersed phase and dispersing are not in equilibrium at a given temperature, ie, they can support more solute to reach degree of saturation.
eg, at 0 ° C 100 g of water dissolve 37.5 NaCl, ie at the given temperature, a solution containing 20g NaCl in 100g of water is not saturated.
SATURATED LIQUID SOLUTION: in these solutions there is a balance between the dispersed phase and dispersing medium, since the temperature is taken into account, the solvent can not dissolve more solute. Eg a saturated NaCl aqueous solution is one that contains 37.5 dissolved in 100 g of water 0 ° C. SATURATED SOLUTION ON SOFT
: represent a class of unstable solution, because it has more solute dissolved than is permitted for the given temperature.
To prepare this type of solute solutions were added in excess, high temperature and then cooling the system slowly. These solutions are unstable, and that adding a very small crystal of the solute, the existing excess rainfall, the same happens with a sudden change in temperature.
Effect of temperature and pressure on solubility of solids and gases
For a drink lost faster when hot gas when it is cold, or chocolate powder that dissolves easily in hot milk, several factors influence these phenomena, among them the temperature and pressure.
Usually the solubility varies with temperature. In most substances, an increase in temperature causes an increase in solubility. Why sugar dissolves better in hot coffee, and milk should be at the boiling point.
pressure changes do not alter the solubility of a solid into a liquid. If a water insoluble solid is not dissolved although the pressure rise sharply exerted on it.
The solubility of gases dissolved in liquids is different from that held by solids. The solubility of a gas in water increases with gas pressure on the solvent, if the pressure decreases, the solubility decreases as well. It is said that the solubility of gases is directly proportional to pressure.
When uncovers a soda bottle, the pressure on the surface of the liquid is reduced and a certain amount of carbon dioxide bubbles rise to the surface. The decrease in pressure allows the CO2 out of solution.
In relation to temperature, dissolved gases in liquids behave as they do the reverse solids. The solubility of a gas in water decreases as temperature increases, which means that the solubility and temperature are inversely proportional.
The gases dissolved in water (oxygen, chlorine and nitrogen) are small bubble that appears when the liquid is heated and has not yet reached the boiling point. When boiling water is fully aerated, so it tastes different from what has unboiled water, therefore it is recommended to aerate the water before drinking. Aqueous solutions
Water is the most abundant biomolecule human being constitutes 65-70% of total body weight. This ratio must be kept very close to these values to maintain water homeostasis, for otherwise the body is faced with pathological conditions due to dehydration or fluid retention. The importance of studying the biomolecule water lies in the fact that all biochemical reactions take place within the water, all nutrients are transported within the water.
molecular structure of water. Is a tetrahedral molecule with the oxygen atom in the center and the two hydrogen atoms at the vertices of the tetrahedron being the other two vertices occupied by the unshared electrons
oxygen Oxygen is an atom has more electronegativity than hydrogen, this makes the water molecule is an electric dipole. This structure explains many of the physical and chemical properties of water either by the hydrogen bond formation or solvation of other molecules.
Physical and chemical properties of water. The properties of water are the basis of a number of functions essential to the integrity of the organism.
biochemical and physiological functions of the water.
It follows that the biochemical and physiological functions of water are consistent with the physicochemical properties have been studied. The water can act as a component of macromolecular proteins, nucleic acids, polysaccharides, can stabilize structure through hydrogen bond formation. That
be considered as universal solvent ionic substance, polar and non-ionic amphipathic facilitates within it can perform all the biochemical reactions and the proper transport of substances in the body.
The water can act as substrate or product of many reactions such as hydrolysis or ester formation. Thermoregulatory
The nature of water, helps keep your balance throughout the body temperature and metabolic heat dissipation we observe in the exercise extensive. Conclusion
This report concluded that the solubility is not only dilute a substance into another, as this is a chemical-physical process which is subject to different factors predominate, such as pressure and temperature.
Finally, it is good to indicate two very important with respect to solubility:
If two solutes are soluble in one solvent, depending on the quantities (small) can dissolve both without any difficulty, but in general the more soluble substance solution moves to the lowest solubility, eg by adding sugar or salt to a drink, immediately there is the escape of gas dissolved in it.
If a solute is soluble in two immiscible solvents (not mixed) with each other, the solute is dissolved in both solvents distributed proportionally according to their solubility in both solvents.
In this work we have seen several aspects of the subject of solutions, which is a very extensive and very important for the life of all human beings on this planet. This issue is very important because without the knowledge to be about solutions, you could not do more with the raw material, or other materials, could not be done for our lives essential materials such as plastic, there are many types This material is used for almost everything, good and as this material there are many others.
Additionally, this paper has attempted to summary information useful and concrete, which is very important because if a reader who does not have much knowledge of the subject not to be confused with both definitions and words that may be strange. In addition it is much more comfortable to read a job well summarized and specific information than any other job that has a lot of information that is not necessary, this often proves to be uncomfortable
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