Solutions mass/volume percent

A To determine mass percent, we need both the mass of ethanol and the mass of solution. From volume percent, we know that 100.0 mL of solution contains 20.0 mL pure ethanol. The density of pure ethanol is 0.789 g/mL. We now can determine the mass of solute (ethanol) and solution. We perform the calculation in one set-up. 

One common way of expressing the relative amount of solute and solvent is through percentage, amount per hundred. There are three ways that we may express this percentage mass percent, mass/volume percent, and volume/volume percent. 

The mass/volume percent of a solution is the mass of the solute (typically in grams) divided by the volume (typically in mL) of the solution and then multiplied by 100% to yield percentage. 

Mg(OH)2 can mean 5 g magnesium hydroxide in 100 mL final volume. This is a mass-volume percent solution. 

Calculate the molcuity and the mass-volume percent solution obtained by dissolving 102.9 g H3PO4 into 642 mL final volume of solution. Be sure to use proper units. (Hint 642 mL = 0.642 L)... 

Next, calculate the mass-volume percent solution ... 

Chemists often express the concentration of an unsaturated solution as the mass of solute dissolved per volume of the solution. This is different from solubility. It is usually expressed as a percent relationship. A mass/volume percent gives the mass of solute dissolved in a volume of solution, expressed as a percent. The mass/volume percent is also referred to as the percent (m/v). 

Suppose that a hospital patient requires an intravenous drip to replace lost body fluids. The intravenous fluid may be a saline solution that contains 0.9 g of sodium chloride dissolved in 100 mL of solution, or 0.9% (m/v). Notice that the number of grams of solute per 100 mL of solution is numerically equal to the mass/volume percent. Explore this idea further in the following problems. 

You need to calculate the concentration of the solution, in grams of solute dissolved in 100 mL of solution. Then you need to express this concentration as a mass/volume percent. 

Three ways of quantitatively expressing the concentration of a solution will be presented here Mass/mass percent, %(m/m), mass/volume percent, %(m/v), and molarity, M. A fourth, molality, will appear later in this chapter. You should know an interesting fact about concentrations. No matter what size sample of a solution you have, be it a teaspoonful or a bucketful, the concentration is the same for both. This is because concentrations are stated in terms of the amount of solute in a fixed amount of solvent 100 g, 100 mL, or 1.00 L. It s like density. The density of mercury is 13.6 g/mL. If I have 100 mL or three drops of mercury, the density of mercury is still 13.6 g/mL. Neither density nor concentration depends on the size of the sample. 

The mass/volume percent, %(m/v), states the mass of solute dissolved in a given volume of solution. Almost always, mass is in grams and volume in milliliters. Mass/volume percent is widely used in medicine for injectable medications and IV solutions. If a solution has a concentration of 2.5%(m/v), it contains 2.5 g of solute in 100 mL of solution. The units of g and mL do not appear in the concentration term, you must remember that with %(m/v), mass is in grams and volume in milliliters. 

The mass/volume percent figure tells that 0.50 g of sugar is in 100 mL of solution. This allows two conversion factors to be written ... 

What is the mass/volume percent concentration of a solution prepared by dissolving 72.5 g of sodium hydroxide, NaOH, in enough water to produce 850.0 mL of solution ... 

The mass/volume percent indicates the solution is to contain 3.00 g of sugar in each 100. mL of solution. This provides the conversion factor to find the volume of solution that contains 1,500 g of sugar (1.500 kg x 1,000g/kg = 1,500 g). 

Determine the mass/volume percent of a solution made by... 

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 volume is milUUters. 

The mass/volume percent is widely used in hospitals and pharmacies for the preparation of intravenous solutions and medicines. For example, a 5% (m/v) glucose solution contains 5 g of glucose in exactly 100 mL of solution. The volume of solution represents the combined volumes of the glucose and H2O. 

Calculate the mass/volume percent (m/v) for the solute in each of the following solutions ... 

Because the cell membranes in biological systems are semipermeable, osmosis is an ongoing process. The solutes in body solutions such as blood, tissue fluids, lymph, and plasma all exert osmotic pressure. Most intravenous (FV) solutions used in a hospital are isotonic solutions, which exert the same osmotic pressure as body fluids such as blood. The percent concentration typically used in IV solutions is similar to the types of percent concentrations we have already discussed, except that the concentration of IV solutions is mass/volume percent m/v). The most typical isotonic solutions are 0.9% (m/v)... 

A student prepared a solution 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 ... 

Another possibility is to express the mass of solute and volume of solution. An aqueous solution with 0.9 g NaCl in 100.0 mL of solution is said to be 0.9% NaCl (mass/volume). Mass/volume percent is extensively used in the medical and pharmaceutical fields. 

An ethanol-water solution is prepared by dissolving 10.00 mL of ethanol, CH3CH2OH d = 0.789 g/mL), in a sufficient volume of water to produce 100.0 mL of a solution with a density of 0.982 g/mL (Fig. 14-1). What is the concentration of ethanol in this solution expressed as (a) volume percent (b) mass percent (c) mass/volume percent (d) mole fraction (e) mole percent (f) molarity (g) molality ... 

For the same solution, the volume percent, mass percent, and mass/volume percent are not necessarily the same. Molarity and molality are also not the same values, because molarity is based on the volume of solution and molality is based on the mass of the solvent. 

---