Specifying Solution Concentration Molarity

Check your answer. Are the xmits correct Does the answer make physical sense  

The units (mL solution) are correct. The magnitude of the answer makes sense because each 100 mL of solution contains 11.5 g sucrose therefore 712 mL should contain a bit more than 77 g, which is close to the given amoxmt of 85.2 g. 

How much sucrose (C12H22O11) in grams is contained in 355 mL (12 oz) of the soft drink in Example 13.2 FOR MORE PRACTiCE Example 13.12 Problems 47,48,49,50,51,52. 

I Note that molarity is abbreviated with a oapital M. 

A second way to express solution concentration is molarity (M), defined as the number of moles of solute per liter of solution. We calculate the molarity of a solution as follows  

---

To end this chapter, Tm going to introduce a chemistry measurement that is based on moles. If you look at the concentrations of various liquids, you will find the terms molar and molarity, as in a 0.5 molar solution of sodium hydroxide. Before explaining this term, I should point out that a solution is something dissolved in a liquid (often water), and if you specify the concentration of a solution, you are saying how much of a particular something you have dissolved in a liquid. Anyway, here is the definition of molarity ... 

Sometimes it may be necessary to prepare a dilute solution of specified concentration from a more concentrated solution of known concentration by adding pure solvent to the concentrated solution. Suppose that the initial concentration (molarity) is C and the initial solution volume is V . The number of moles of solute is (c mol F )(Vi F) = C V mol. This number does not change on dilution to a final... 

The standard state of a substance is a reference state that allows us to obtain relative values of such thermodynamic quantities as free energy, activity, enthalpy, and entropy. All substances are assigned unit activity in their standard state. For gases, the standard state has the properties of an ideal gas, but at one atmosphere pressure. It is thus said to be a hypothetical state. For pure liquids and solvents, the standard states are real states and are the pure substances at a specified temperature and pressure. For solutes In dilute solution, the standard state is a hypothetical state that has the properties of an infinitely dilute solute, but at unit concentration (molarity, molality, or mole fraction). The standard state of a solid is a real state and is the pure solid in its most stable crystalline form. 

When a component A is added to a solvent, there is a volume change usually the volume increases but occasionally it decreases. The volume change on adding 1 mol of A is termed the partial molar volume, and it is denoted by It is dependent on all the thermodynamic conditions the temperature, the pressure, the nature of the solvent, the concentration of A, the concentration of all the other solutes, and any other pertinent thermodynamic variables. Measuring is equivalent to measuring the solution density at specified conditions, a measurement that can be made quite accurately. For stable solutes, partial molar volumes are frequently quoted to a precision of 0.01 cm mol It often suffices to consider only the partial molar volume at... 

Solubility - A quantity expressing the maximum concentration of some material (the solute) that can exist in another liquid or solid material (the solvent) at thermodynamic equilibrium at specified temperature and pressure. Common measures of solubility include the mass of solute per unit mass of solution (mass fraction), mole fraction of solute, molality, molarity, and others. 

The increase of enthalpy that takes place when one mole of solute is dissolved in a sufficiently large volume of solution (which has a particular composition), such that there is no appreciable change in the concentration, is the molar differential heat of solution. When stating a value for this quantity, the specified concentration and temperature must also be quoted. Because the differential heat of solution is almost constant in very dilute solutions, the molar differential and integral heats of solution are equal at infinite dilution. At higher concentrations, the differential heat of solution generally decreases as the concentration increases. 

A solution consists of one or more solutes dissolved in a solvent (see Section 0.1). In order to apply the quantitative mass-mole relationships to a solution, we must specify its concentration, defined as the amount of particular solute present in a given amount of solution. Chemists use several different concentration units, each of which has advantages as well as limitations. Let us examine the four most common units of concentration percent by mass, mole fraction, molarity, and molality. 

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. 

Knowing the molarity of a solution, you can readily obtain a specified amount of solute. All you have to do is to calculate the required volume, as in Example 3.2b. Upon measuring out that volume, you should obtain the desired number of moles or grams of solute. Concentrations of reagents in the general chemistry laboratory are most often expressed in molarities. We will have more to say about molarity and other concentration units in Chapter 10. 

Note that the brackets, [ ], refer to the concentration of the species. K,p is the solubility product constant hence [Cu " ] and [OH] are equal to the molar concentrations of copper and hydroxyl ions, respectively. The K p is commonly used in determining suitable precipitation reactions for removal of ionic species from solution. In the same example, the pH for removal of copper to any specified concentration can be determined by substituting the molar concentration into the following equation ... 

Chemists often indicate the concentration of a substance in water solution in terms of the number of moles of the substance dissolved per liter of solution. This is called the molar concentration. A one-molar solution (1 M) contains one mole of the solute per liter of total solution. a two-molar solution (2 M) contains two moles of solute per liter, and a 0.1-molar solution (0.1 M) contains one-tenth mole of solute per liter. Notice that the concentration of water is not specified, though we must add definite amounts of water to make the solutions. 

As a result standard solutions are now commonly expressed in terms of molar concentrations or molarity (AT). Such standard solutions are specified in terms of the number of moles of solute dissolved in 1 litre of solution for any solution,... 

It follows from this, that a molar solution of sulphuric acid will contain 98.074 grams of sulphuric acid in 1 litre of solution, or 49.037 grams in 500 mL of solution. Similarly, a 0.1 M solution will contain 9.8074 grams of sulphuric acid in 1 litre of solution, and a 0.01 M solution will have 0.980 74 gram in the same volume. So that the concentration of any solution can be expressed in terms of the molar concentration so long as the weight of substance in any specified volume is known. 

Chemists need to be able to specify the composition of mixtures quantitatively. For example, a chemist may need to monitor a pollutant, administer a dosage, or transfer a known amount of a solute. In this section we examine the properties and types of mixtures as well as how to use the molar concentration of a dissolved substance to analyze solutions quantitatively. 

Any solution contains at least two chemical species, the solvent and one or more solutes. The mass of a solution is the sum of the masses of the solvent and all dissolved solutes. To answer questions such as How much is there about solutions, we need to know the amount of each solute present in a specified volume of solution. The amount of a solute in a solution is given by the concentration, which is the ratio of the amount of solute to the amount of solution. In chemistry the most common measure of concentration is molarity (M). Molarity is the number of moles of solute (n) divided by the total volume of the solution (V) in liters ... 

The problem specifies a solution volume of 1.5 L with a total molarity of 0.150 mol/L. The total molarity is the combined concentration of the two buffer components il/acetate + - acetic acid 0.150 M Use the total volume of the solution, 1.5 L, to determine the total number of moles in the system ... 

Consequently, a more rigorous treatment particularly specifies Kp as the ratio of the activities of the substance (A) in the two solvents instead of their concentrations. Hence, for dilute solutions, at a specified constant pressure and temperature, the mole fraction of a solute is directly proportional to its concentration in molarity or mass per unit volume which implies that these may be employed instead of mole-fraction in Eq. 

The conventional method for determining the cell constant of a conductance cell involves the use of solutions of known specific resistance. The a-queous KC1 solutions of Jones and Bradshaw 32) are the currently accepted standards. These workers carefully measured three solutions of given weight concentrations corresponding to molarities of about 1,0.1 and 0.01. There are two disadvantages to this approach. First, a solution of an exactly specified concentration must be prepared. Second, it does not permit measurement of the cell constant over a range of concentrations in order to test for stray current leakages which would cause systematic variations in the calculated constant. 

Equilibrium constants are dimensionless but. when specifying concentrations, you must use units of molarity (M) for solutes and bars for gases. 

Notice that the units of e are defined by the concentration units of the tyrosine solution M) and the dimension units of the cuvette (cm). Although E is most often expressed as a molar absorption coefficient, you may encounter other units such as A°/0, which is the absorbance of a l°/o (w/v) solution of pure absorbing material in a 1-cm cuvette at a specified wavelength, A. 

The actual molar concentration of an enzyme in a cell-free extract or purified preparation is seldom known. Only if the enzyme is available in a pure crystalline form, carefully weighed, and dissolved in a solvent can the actual molar concentration be accurately known. It is, however, possible to develop a precise and accurate assay for enzyme activity. Consequently, the amount of a specific enzyme present in solution is most often expressed in units of activity. Three units are in common use, the international unit (IU), the katal, and specific activity. The International Union of Biochemistry Commission on Enzymes has recommended the use of a standard unit, the international unit, or just unit, of enzyme activity. One IU of enzyme corresponds to the amount that catalyzes the transformation of 1 p,mole of substrate to product per minute under specified conditions of pH, temperature, ionic strength, and substrate concentration. If a solution containing... 

Remember that the standard state of a substance is its pure form at a pressure of 1 bar. For a solute, it is for a concentration of 1 mol-L-1. The value of AGr refers to any chosen composition of the reaction mixture and represents the difference in molar free energy between the products and reactants at the concentrations present at a specified stage of the reaction. 

Consistent notation is adopted throughout this book. Diblock copolymers are written poly(monomer A) poly (monomer B) or PA-PB, where examples of PA and PB are illustrated in Fig. 1.2. Similarly, triblock copolymers are written poly(monomer A)-poly(monomer B)-poly(monomer C) or PA-PB PC. Deuterated blocks are denoted dpoly(monomer A) or dPA. The molar mass of a copolymer is denoted by M, or Af corresponding to the weight- or number-average respectively, and the composition is specified by the volume fraction of one component,/. In solution, the volume fraction of a copolymer is denoted [Pg.3]

---