Concentrated solutions mass percent

The concentration of a solution can be expressed in many ways, including molarity (moles of solute per liter of solution), mole fraction (moles of solute per mole of solution), mass percent (mass of solute per mass of solution times 100%), and molality (moles of solute per kilogram of solvent). When equilibrium is reached and no further solute dissolves in a given amount of solvent, a solution is said to be saturated. The concentration at this point represents the... 

This table gives the density of aqueous sulfuric acid solutions as a function of concentration (in mass percent of H SO ) and temperature. 

As we have seen, the amoxmt of solute in a solution is an important property of the solution. For example, the amoxmt of carbon dioxide in the water at the bottom of Lake Nyos is an important predictor of when the deadly event may repeat itself. A dilute solution is one containing small amounts of solute relative to solvent. If the water at the bottom of Lake Nyos were a dilute carbon dioxide solution, it would pose little threat. A concentrated solution is one containing large amounts of solute relative to solvent. If the carbon dioxide in the water at the bottom of Lake Nyos becomes concentrated (through the continual feeding of carbon dioxide from magma into the lake), it becomes a large threat. A common way to report solution concentration is mass percent. 

Solution Concentration Solution concentration is used to specify how much of the solute is present in a given amount of solution. Three common ways to express solution concentration are mass percent, molarity, and molality. 

Solution Concentration Solution concentration is useful in converting between amounts of solute and solution. Mass percent and molarity are the most common concentration units. Molality is used to quantify colligative properties such as freezing point depression and boiling point elevation. 

It is frequently necessary to convert from one concentration unit to another This problem arises, for example, in making up solutions of hydrochloric acid. Typically, the analysis or assay that appears on the label (Figure 10.2, p. 263) does not give the molarity or molality of the add. Instead, it lists the mass percent of solute and the density of the solution. 

The label on a bottle of concentrated hydrochloric acid. The label gives the mass percent of HCI in the solution (known as the assay] and the density (or specific gravity) of the solution. The molality, molarity, and mole fraction of HCI in the solution can be calculated from this information. 

Recap 50. mL samples of known concentration of[Ni(NH3)J2+ were made up by using NiS04 6 H20. The concentrations were then plotted versus their absorbance. The unknown solution s absorbance was then extrapolated from this graph and used in the calculation for the mass percent ofNi2+. 

Percent solution is another common way to express concentration. The precise units of percent solution typically depend on the phase of each component. For solids dissolved in liquids, mass percent is usually used ... 

This kind of measurement is sometimes called a mass-mass percent solution because one mass is divided by another. Very dilute concentrations (as in the concentration of a contaminant in drinking water) are sometimes expressed as a special mass percent called parts per million (ppm) or parts per billion (ppb). In these metrics, the mass of the solute is divided by the total mass of the solution, and the resulting fraction is multiplied by 10 (ppm) or by 10 (ppb). 

Clearly, paying attention to units is important when working with concentration. Only by observing which units are attached to a measurement can you determine whether you re working with molarity, with mass percent, or with a mass-mass, mass-volume, or volume-volume percent solution. 

In daily life, it s often sufficient to describe a solution as either dilute or concentrated. In scientific work, though, it s usually necessary to know the exact concentration of a solution—that is, to know the exact amount of solute dissolved in a given amount of solvent. There are many ways of expressing concentration, each of which has its own advantages and disadvantages. We ll look briefly at four of the most common methods molarity, mole fraction, mass percent, and molality. 

Closely related to mass percent, and particularly useful for very dilute solutions, are the concentration units parts per million (ppm) and parts per billion (ppb) ... 

PROBLEM 11.3 What is the mass percent concentration of a saline solution prepared by dissolving 1.00 mol of NaCl in 1.00 L of water ... 

What is the mass percent concentration of the following solutions ... 

The concentration of a solution can be expressed in mass percent, as described below. 

In chemistry, solutions are prepared so that a specific concentration of particles, the solute, is added to a specific volume of solvent. When a uniform mixture of solute and solvent results, a solution is formed. The concentration of a solution is expressed as the ratio of solute to solution, solution being solute plus solvent. In the next demonstration, we examine a change in value through dilution using mass percent as a means of expressing concentration of the solution. In mass percent, the ratio of grams of solute to grams of solution, multiplied by 100, is used to calculate the mass percent of the solution. 

Students will define solution and explain how to express the concentration of a solution using mass percent. 

Mass percent is the concentration of a solution in grams of solute per grams of solution. The mass percent would be 10%. The calculation is as follows 20.0 g of solute divided by 200.0 g of solution /100 = 10%. 

Solution concentrations are often presented as a percent concentration (mass percent). Ten percent NaOH solution is used to break down wood fibers often used to make paper. For this example, how many grams of solute are added to how many grams of solvent to prepare 100 g of 10% NaOH solution ... 

Given the solution composition in mass percent, it is easy to compute the mole fractions of solute and solvent and the molal concentration of solute. 

For example, what is the percent by weight concentration of glucose in a solution prepared by dissolving 25 g of glucose in 475 g of water As with all solutions problems, we need to be very careful about the definitions. The mass of solute is obviously 25 g, but what about the grams of solution The solution consists of both glucose and water, so the total solution mass is 500 g, not 475 g. So the percent concentration is ... 

A mass/mass percent gives the mass of a solute divided by the mass of solution, expressed as a percent. The mass/mass percent is also referred to as the percent (m/m), or the mass percent. It is often inaccurately referred to as a weight (w/w) percent, as well. Look at your tube of toothpaste, at home. The percent of sodium fluoride in the toothpaste is usually given as a w/w percent. This can be confusing, since weight (w) is not the same as mass (m). In fact, this concentration should be expressed as a mass/mass percent. 

For example, 100 g of seawater contains 0.129 g of magnesium ion (along with many other substances). The concentration of Mg2+ in seawater is 0.129 (m/m). Notice that the number of grams of solute per 100 g of solution is numerically equal to the mass/mass percent. 

The concentration of a solid solution, such as an alloy, is usually expressed as a mass/mass percent. Often the concentration of a particular alloy may vary. Table 8.3 gives typical compositions of some common alloys. 

If 55 g of potassium hydroxide is dissolved in 100 g of water, what is the concentration of the solution expressed as mass/mass percent ... 

The leaves of a rhubarb plant contain a relatively high concentration of oxalate ions, C2042-. Oxalate ions are poisonous, causing respiratory failure. To determine the percent of oxalate ions, a student measured the mass of some leaves. Then the student ground up the leaves and added excess calcium chloride solution to precipitate calcium oxalate. The student tested 238.6 g of leaves. The dried mass of calcium oxalate was 0.556 g. What was the mass percent of oxalate ions in the leaves ... 

The density of vinegar is 1.01 g/mL. (The density of the more concentrated vinegar solution is greater than the density of the less concentrated solution. You can ignore the difference, however.) Calculate the mass of the vinegar sample. Find the percent by mass of acetic acid in the sample. 

The gaseous products are then passed through a concentrated solution of KOH to remove the C02. After passage through the KOH solution the gas contains N2 and is saturated with water vapor. In a given experiment a 0.253-g sample of a compound produced 31.8 mL of N2 saturated with water vapor at 25°C and 726 torr. What is the mass percent of nitrogen in the compound (The vapor pressure of water at 25°C is 23.8 torr.)... 

In a solution of acetone (CH3COCH3) and ethanol (C2H5OH), the mole fraction of acetone is 0.40. What is the concentration of acetone in terms of mass percent ... 

Percent solute rejection or removal. The other parameter important in the design and operation of RO units is the percent rejection or removal of solutes. Let Qo be the feed inflow, [C ] be the feed concentration of solutes, Qp be the permeate outflow, [Cp] be the permeate concentration of solutes, be the concentrate outflow, and [CJ be the concentrate concentration of solutes. By mass balance of solutes, the percent rejection R is... 

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