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Como preparar soluciones
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How to make a solution:

The following "how to make a solution" is from CAROLINA

Remember: Always follow appropriate lab safety procedures when mixing and storing chemicals.
When a substance, called a solute, is dissolved in another substance, called the solvent, a solution is formed. A solution is a uniform distribution of solute in solvent. For example, vinegar is a solution of acetic acid, the solute, in water, the solvent. The amount of solute in a solvent is important and can be expressed in several different ways. Some common units of concentration will be discussed in this manual.

1.
Molar solutions

Molarity (M) means the number of moles of solute per liter of solution. To prepare a 1 M solution, slowly add the molecular weight (x g/mol) of compound to 500-mL distilled or deionized water in a 1000-mL volumetric flask half filled with distilled or deionized water. Allow the compound to dissolve completely, swirling the flask gently if necessary. Once the solute is completely dissolved and the solution is at room temperature, dilute to the mark with water. Invert the flask several times to mix.

To make a 1 M solution of sodium hydroxide (40g/mol), slowly add 40 g sodium hydroxide to 500 mL distilled or deionized water in a 1000-mL volumetric flask. When all the solid is dissolved and the solution is at room temperature, dilute to the mark and invert the flask several times to mix.To make a 1 M solution of acetic acid, dissolve 60.05 g acetic acid in 500 mL distilled or deionized water in a 1000-mL volumetric flask. Since acetic acid is a liquid, it may also be measured by volume. Divide the mass of the acid by its density (1.049 g/mL) to determine the volume (57.24 mL). Use either 60.05 g or 57.24 mL acetic acid to make the solution. Swirl the flask gently to mix the solution. When the solution is at room temperature, dilute to the mark and invert the flask several times to mix. Always add acid to water

2.
Percent solutions

a.
Mass percent means the number of grams of solute per 100 g of solution. For example, 10 g sodium chloride in 90 g water is a 10% by mass solution.

mass percent = mass of solute/mass of solution= 10 g / (10 g + 90 g) x 100%= 10%

b.
Volume percent means the number of milliliters of solute per 100 mL of solution. The volume percent of a solution cannot be calculated directly from the volumes of its components because the final volume may not equal the sum of the components’ volumes. To prepare volume percent solutions, first determine the final volume and concentration of the desired solution and then determine the amount of solute. Dilute the solute in sufficient solvent to produce the final volume of desired solution. For example, to prepare 100 mL of a 10% by volume solution of acetic acid, dilute 10 mL acetic acid with distilled or deionized water to make 100 mL of solution.
Note: Solutions of concentrated reagents, such as 37% hydrochloric acid and 85% phosphoric acid, are percent solutions by mass. In general, percent solutions are by mass.

3.
Dilutions

When preparing a dilution, decide the volume and molar concentration of the resulting solution that you require. Use the following equation to determine how much of the concentrated reagent is needed to prepare the diluted solution,

M reagent x V reagent = M dilution x V dilution

where M is molarity and V is volume.

Slowly add the calculated volume of concentrated reagent to a proper-sized volumetric flask half filled with distilled or deionized water and swirl the flask to mix. Once the solution is at room temperature, dilute to the mark with water and invert the flask several times to mix.

For example, what volume of 10 M acetic acid is required to prepare 1.0 L of 0.50 M acetic acid?

10 M x V reagent = 0.50 M x 1.0 L V reagent = 0.050 L = 50 mL

A volume of 50 mL of 10 M acetic acid is required to prepare 1.0 L of 0.50 M acetic acid.

4.
Special cases

Often it is necessary to prepare solutions from chemicals that are less than 100% pure. To prepare solutions from these impure chemicals, first decide the volume and molarity of the required solution. Multiply the solution’s volume by its molarity. The product (n) is the number of moles of pure chemical needed to produce that solution.

M pure x V pure = n pure

Because the percent purity of chemicals sold commercially is measured by mass, first calculate the mass of the pure chemical needed to make the solution. Multiply the number of moles of pure chemical times the gram formula weight of the chemical.

mass of pure chemical = n pure x gram formula weight

The mass of the impure chemical times the percent purity in decimal form equals the mass of the pure chemical. Divide the mass of pure chemical by the percent purity to yield the mass of the impure chemical.
mass of pure chemical = mass of impure chemical x percent purity mass of impure chemical = mass of pure chemical / percent purity

The above equations may be combined into one equation.

mass of impure chemical = M pure x V pure x gram formula weight / percent purity

Use this equation if the chemical in question is a solid.

For example, what mass of potassium hydroxide that is 85.9% pure is needed to prepare 1.0 L of a 0.25 M solution of potassium hydroxide? The gram formula weight of potassium hydroxide is 56.11 g/mol.

mass of impure chemical = M pure x V pure x gram formula weight/percent purity
= 0.25 M × 1.0 L × 56.11 g/mol ÷ 0.859= 16 g

If the chemical in question is a liquid, then one more calculation is required. Divide the mass of the impure chemical by its density to yield the volume of chemical.

volume of impure chemical in mL = mass of impure chemical in g/density of impure chemical in grams per milliliter
Again, combine the previous equations.

volume of impure chemical = M pure x V pure x gram formula weight / (percent purity x density)
For example, what volume of hydrochloric acid that is 37.1% pure is needed to prepare 1.0 L of a 0.10 M solution of hydrochloric acid? The gram formula weight of hydrochloric acid is 36.46 g/mol, and the density of 37.1% hydrochloric acid is 1.2 g/mL.

volume of impure chemical = M pure x V pure x gram formula weight / (percent purity x density)
= 0.10 M × 1.0 L × 36.46 g/mol ÷ (0.371 x 1.2 g/mL)= 8.2 mL

5.
Normal solutions

Another concentration term sometimes used is normality. Normality (N) means the number of equivalents of solute per liter of solution. An equivalent is defined separately for acid-base and reduction-oxidation (redox) chemistry.
In acid-base chemistry, an equivalent is the mass of chemical that donates or accepts one mole of protons. For example, sulfuric acid is a diprotic acid. One-half mole of sulfuric acid therefore provides one mole of protons. To prepare a 1 N solution of sulfuric acid, slowly add 0.5 gram formula weight of sulfuric acid to a clean 1-L volumetric flask and fill to the mark with distilled or deionized water.

In redox chemistry, an equivalent is the mass of chemical that donates or accepts one mole of electrons. Determine the number of electrons a chemical donates or accepts from its half-reaction. For example, one mole of aluminum (III) reacts with 3 moles of electrons to give one mole of aluminum metal.

Al 3+ + 3e – Al

To prepare a 1 N solution of aluminum (III), slowly add 0.333 g formula weight of an aluminum (III) compound to a clean 1-L volumetric flask and fill to the mark with distilled or deionized water.

Tincion de azul coomassie para geles de poliacrilamida (PAGE)

Tincion, decoloracion y secado de geles de poliacrilamida (PAGE)


Para teñir el gel
1). Una vez que ha finalizado la corrida electroforetica, retirar el gel del casette y colocarlo en un recipiente hermetico de plastico (tuper)
2). Añadir 50 mL de la solucion de tincion
3). Incubar a 22 oC, 12 h, en agitacion continua

Para desteñir el gel
1). Incubar en 50 mL de solucion destiñidora durante una hora
2). Repetir el procedimiento dos o tres veces mas hasta que aparezcan las bandas teñidas de azul y el fondo casi transparente

Para secar el Gel
1). Incubar durante 12 h en glicerol al 20% en agua BD.
2). Fotografiar o escanear
3). Secar en el bastidor de acrilico a 22 oC durante dos o tres dias. (se puede acelerar el proceso si se le coloca un foco incandescente de 60 W lo mas cercano posible al gel, pero sin que llege a tocarlo).


Solucion de tincion
1). 2.5 g Azul Brillante Coomassie R-250
2). 450 mL metanol
3). 100 mL acido acetico glacial
4). Aforar a 1 L con agua BD
Nota: Esta solucion se puede recuperar y reusar nuevamnte si se filtra y se mezcla con la solucion de coomassie

Solucion destiñidora
1). 200 mL de metanol
2). 150 mL de acido acetico
3). 650 mL de agua BD
Nota: Esta solucion se puede recuerar y reusar si se filtra con un poco de carbon activado.

Tincion de plata para gel de poliacrilamida (PAGE)

Tincion con plata para gel de poliacrilamida (PAGE)

1). Nuca tocar el gel con los dedos desnudos, use guantes
2). Inmeditamente despues de retirar el gel (8 x 10 cm, de 1 mm de espesor) del casette donde se realizo la corrida electroforetica, coloquelo en un recipiente de vidrio con 100 mL de metanol al 40% y acido acetico al 10% durante 60 min.
3). Incubar con 100 mL de metanol al 40% por 30 min
4). Incubar con 100 mL de agua BD por 30 min
5). Incubar con 100 mL de tiosulfato de sodio al 0.01% en agua durante 1 min
6). Enjuagar con 100 mL de agua DB durante 5 min, repita este mismo paso un vez mas
7). Incubar con 100 mL de cloruro de plata al 0.1 % durante 30 min a 4 oC
8). Enjuagar con 100 mL de agua DB durante 5 min. y repita un vez mas.
9). Incubar con 100 mL de cabonato de sodio al 2% en formalina (formol al 35%) al 0.04% revelador durante 5 min y repita una vez mas
10). Incubar con 100 mL de acido acetico al 5% durante 10 min.
11). Incubar con 100 mL de acido acetico al 1% antes de fotografiar o escanear
12). Enjuagar con 100 mL de agua BD tres veces
13). Incubar en glicerol al 20% en agua BD durante 12 h.
14). Secar en marcos de acrilico y papel celofan.

Teapeutica antioxidativa (01)

Terapeutica antioxidativa (antioxidantes orales)

Ensalada de apio y naranja

Ingredientes para 4 personas (o dos tragones)

1). Una rama de apio, lavado, incubado previamente a 90oC durante 8 min, y cortado en cubitos
2). 8 nueces peladas (16 mitades), cortadas en pedacitos asi de chiquitos.
3). 4 aceitunas negras
4). 4 aceitunas verdes
5). 2 naranjas peladas y en gajos
6). Mezclar vigorosamente
7). 4 cucharadas de aceite de oliva.
8). 1 limón.
9). 1 cucharadita de mostaza.
10). Perejil
11). Sal y pimienta
12). Lechugas variadas
13). Mezclar vigorosamente
14). Disfrutar en compañia de buen@s amig@s y con alguna otra de la recetas previas.


Comentario dietetico

Las ensaladas son platos muy nutritivos y fáciles de elaborar.
Esta receta presenta una ensalada de apio y naranja, ambos alimentos de bajo contenido calórico y ricos en vitaminas, minerales y sustancias con acción antioxidante.
Se añaden también otros alimentos con propiedades atioidativas como nueces y aceitunas, fuente de grasas insaturadas que contribuyen a disminuir los niveles de colesterol en sangre.
Los vegetals son ricos en fibra, vitaminas y minerales.
La variedad de ingredientes y su colorido, los convierten en un plato muy apetecible y atractivo.

Determinacion de fosfato total

Determinacion de fosfato total

1). Pesar 0.5 mg de muestra de tejido (en un tubo Pyrex)
2). 50 uL de nitrato de magnesio al 10%
3). Evaporar hasta secar directamente sobre a llamade un mechero (no muy intensa)
4). Enfriar a temperatura ambiente
5). 300 uL de HCl 1 N
6). Inubar a 100oC, 15 min. (baño maria o seco)
7). 700 uL de Ac. ascorbico / molibdato (1 parte a 6 partes mezcladas justo antes de añadir)
8). Incubar a 45 oC, 20 min.
9). Leer la absorbancia a 820 nm contra el blanco de reactvos (la absorbanbcia cae enter 0.240 for 0.01 µmol fosfato).

Peparacion de la curva de calibracion

0.001 M de fosfato use 100, 200, 300, 400, 500 ul y afore a 500 ul de volumen final con agua BD.

Reactivos

Nitrato de magnesio al 10% disuelto en etanol
HCl 0.1 M
Acido ascorbico al 10% (1 g/10 mL)
Molbdato de amonio 0.42% en acido sulfurico 1 N (0.42 g + 2.66 mL H2SO4 y aforar a 100 mLcon agua BD)

* El acido ascorbico es estable a 2 - 4oC durante aprox. 7 semanas.

Induccion de citocromo P-450

Induccion de citocromo P-450 via oral con etanol tipo Ron

1). 40 mL de etanol bebestible (Ron Potosi Añejo [Mexico], Ron Matusalen Clasico [Rep. Dominicana], o Ron Cacique Añejo [Venezuela]).
2). 250 mL de refresco (soda) de sabor cola (xx-cola).
3). 3 a 10 mL de extracto fresco de limon
4). Mezclar con gentileza
5). Disfrutar con tranquilidad y en compañia de buena-os amiga-os
6). Repetir la dosis unas dos veces o tres veces mas (no abusar de su consumo debido a sus efectos secundarios ya que se genera estres oxidativo por exceso de aldehidos, acetonas, y oxidrihilos, ademas de otros efectos secundarios mejor conocidos y sufridos)
7). No consumir esta mezcla si se tiene que manejar, poco antes de algun examen, o de andar de galan, ya que el alcohol invita pero no ayuda.
8). No mezclar con ningun otro tipo de farmacoterapia.
9). Se puede acompañar de alimentos de buena manufactura como jamones, encurtidos y semillas variadas.
10). Una vez ingeridas las dosis arriba recomendadas es conveniente tomar un par de vasos de agua mineral, e irse a dormir.