Solution Composition Mass Percent

I AIM To understand the concentration term mass percent and learn how to calculate it. 

Describing the composition of a solution means specifying the amount of solute present in a given quantity of the solution. We typically give the amount of solute in terms of mass (number of grams) or in terms of moles. The quantity of solution is defined in terms of mass or volume. 

One common way of describing a solution s composition is mass percent (sometimes called weight percent), which expresses the mass of soiute present in a given mass of solution. The definition of mass percent is  

For example, suppose a solution is prepared by dissolving 1.0 g of sodium chioride in 48 g of water. The solution has a mass of 49 g (48 g of H2O pius 1.0 g of NaCl), and there is 1.0 g of solute (NaCl) present. The mass percent of solute, then, is 

Example 14.1 Solution Composition Calculating Mass Percent 

Although a chemical compound always has the same composition, a solution is a mixture and the amounts of the substances present can vary in different solutions. For example, coffee can be strong or weak. Strong coffee has more coffee dissolved in a given amount of water than weak coffee. To describe a solution completely, we must specify the amounts of solvent and solute. We sometimes use the qualitative terms concentrated and dilute to describe a solution. A relatively large amount of solute is dissolved in a concentrated solution (strong coffee is concentrated). A relatively small amount of solute is dissolved in a dilute solution (weak coffee is dilute). 

Although these qualitative terms serve a useful purpose, we often need to know the exact amount of solute present in a given amount of solution. In the next several sections, we will consider various ways to describe the composition of a solution. 

Obtain five paper cups containing five different colored solutions. You will also need a clear, colorless plastic straw. 

Each of your five solutions has a different concentration of NaCl. Your task is to order the solutions from least concentrated to most concentrated. You may only use the five solutions and the straw. You may need to experiment a little and you may make some mistakes along the way. 

How does concentration of the solution relate to density of the solution  

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CHEMISTRY IN FOCUS Green Chemistry 480 Solution Composition An Introduction 480 Solution Composition Mass Percent 481 Solution Composition Molarity 483... 

Solution composition can be specified by the mass percents of solute and solvent. Thus a 10% aqueous... 

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. 

The table below lists the standard emf values of the cell H2/HCl/AgCl, Ag in water as well as in various aqueous solutions of three common organic solvents, all alcohols, at different temperatures.1 2 The compositions are given as mass percent of the alcohol in water. All emf values are expressed in volts. 

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. 

Other ways of describing solution composition are also useful. Mass percent (sometimes called weight percent) is the percent solute by mass in the solution ... 

You take 20.0 g of a sucrose (Ci2H22On) and NaCl mixture and dissolve it in 1.0 L of water. The freezing point of this solution is found to be —0.426°C. Assuming ideal behavior, calculate the mass percent composition of the original mixture, and the mole fraction of sucrose in the original mixture. 

Another way of providing information about solution composition is to express how much solute is present relative to the maximum amount the solution could hold. If the amount of solute dissolved is less than the maximum that could be dissolved, the solution is called an unsaturated solution. The oceans of Earth are examples of imsaturated saltwater solutions. They could hold a higher concentration of salt than they do now. The maximum concentration of salt water is approximately 36 g of salt dissolved per every 100 g of water, or 36 percent by mass. Such a solution, which holds the maximum amount of solute per amoimt of the solution under the given conditions, is called a saturated solution. 

The four most common ways to describe solution composition are mass percent, mole fraction, molarity, and molality. Define each of these solution composition terms. Why is molarity temperature-dependent, whereas the other three solution composition terms are temperature-independent ... 

Consider an aqueous solution containing sodium chloride that has a density of 1.01 g/mL. Assume the solution behaves ideally. The freezing point of this solution at 1.0 atm is -1.28X. Calculate the percent composition of this solution (by mass). 

Solution composition can be described in many ways. Two of the most important are in terms of mass percent of solute ... 

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