What are solutions

Solutions are homogeneous mixtures that contain a solute and a solvent. Solutions, solutes, and solvents may be solid, liquid, or gaseous. A substance that dissolves in a solvent is said to be soluble in that solvent. A substance that does not dissolve in a solvent is said to be insoluble in that solvent. Two liquids that are soluble in each other are said to be miscible. Liquids that are not soluble in each other are immiscible. 

A soluble substance is able to dissolve in a solvent because attractive forces between solvent and solute particles are strong enough to overcome the attractive forces holding the solute particles together. Solvent particles surround solute particles to form a solution in a process called solvation. Solvation in water is also called hydration. 

In general, like dissolves like that is, polar substances tend to be soluble in polar solvents, and nonpolar substances tend to be soluble in nonpolar solvents. When an ionic compound dissolves in water, a polar solvent, the attractions between the water dipoles and the ions cause the ions to become solvated. The ions break away from the surface of the ionic soUd and move into solution. The overall energy change that occurs during solution formation is called the heat of solution. 

There are three common ways to increase the collisions between solute and solvent particles and thus increase the rate at which the solute dissolves agitating the mixture, increasing the surface area of the solute, and increasing the temperature of the solvent. Increasing the temperature causes collisions to become more frequent and to have greater energy. 

The solubility of a solute is the maximum amount of the solute that will dissolve in a given amount of solvent at a specified temperature and pressure. Solubility is usually expressed in grams of solute per 100 g of solvent. A solution that contains the maximum amount of dissolved solute for a given amount of solvent at a specific temperature and pressure is called a saturated solution. An 

Have you ever thought of the importance of soluhons Even if you haven t, the fact is that solutions are all around you. They are even inside you you and all other organisms are composed of cells containing solutions that support life. You inhale a solution when you breathe. You are immersed in a solution whether standing in a room or swimming in a pool. Structures such as the ones shown in the photo on the previous page would not be possible without steel, yet another solution. 

Cell solutions, ocean water, and steel may appear quite dissimilar, but they share certain characteristics. In Chapter 3, you learned that solutions are homogeneous mixtures containing two or more substances called the solute and the solvent. The solute is the substance that dissolves. The solvent is the dissolving medium. When you look at a solution, it is not possible to distinguish the solute from the solvent. 

Q The air you breathe is a gas soiution primariiy containing oxygen, nitrogen, and argon. 

The bioiogicai reactions necessary for iife occur in aqueous soiutions within ceiis. Q A soiid soiution of titanium and nickei is commoniy used for braces in orthodontia. 

Gas in iiquid Carbonated water Water (iiquid) Carbon dioxide (gas) 

---

Given that a sequence folds to a known native stmcture, what are the mechanisms in the transition from the unfolded confonnation to the folded state This is a kinetics problem, the solution of which requires elucidation of the pathways and transition states in the folding process. 

Importantly for direct dynamics calculations, analytic gradients for MCSCF methods [124-126] are available in many standard quantum chemistiy packages. This is a big advantage as numerical gradients require many evaluations of the wave function. The evaluation of the non-Hellmann-Feynman forces is the major effort, and requires the solution of what are termed the coupled-perturbed MCSCF (CP-MCSCF) equations. The large memory requirements of these equations can be bypassed if a direct method is used [233]. Modem computer architectures and codes then make the evaluation of first and second derivatives relatively straightforward in this theoretical framework. 

Continue the recursive steps until the solution settles down (when k = 50, or kT = 5 seconds) and hence determine the steady-state value of the feedback matrix K(0) and Riccati matrix P(0). What are the closed-loop eigenvalues ... 

When compound B is dissolved in FSO3H at —78°C, the NMR spectrum shows that a carbocation is formed. If the solution is then allowed to warm to — 100°C, a different ion forms. The first ion gives compound C when quenched with base, while the second gives D. What are the structures of the two carbocations, and why do they give different products on quenching ... 

Examine health reeords in your plant. Organize these by work areas and assess whether there are statistically higher ineidents that support respiratory ailments, including cold and flu statistics. If the data supports a particular work area as having a problem, can you identify the reasons If so, what are they and how would you go about better defining the problem and a solution ... 

What are the essential features of surfactant systems An important ingredient is obviously the repulsion between water and nonpolar molecules or molecule parts, the hydrophobic force. This interaction is however highly nontrivial, and its analysis is still an active field of research [4,22,23]. Qualitatively, it is usually attributed to the strong orientational and positional correlations between nonpolar molecules in solution and the surrounding water molecules. The origin of the interaction is therefore entropic free water forms a network of hydrogen bonds. In the neighborhood... 

Given 0.1 M solutions of Na3P04 and H3PO4, describe the preparation of 1 L of a phosphate buffer at a pH of 7.5. What are the molar concentrations of the ions in the final buffer solution, including Na and H ... 

A relaxed, circular, double-stranded DNA molecule (1600 bp) is in a solution where conditions favor 10 bp per turn. What is the value of Lq for this DNA molecule Suppose DNA gyrase introduces 12 negative snpercoils into this molecule. What are the values of L, W, and T now What is the snperhelical density, cr ... 

A copper strip with a mass of 2.00 g is dipped into a solution of AgN03. After some time has elapsed, the copper strip is coated with silver. The strip is removed from the solution, dried, and weighed. The coated strip has a mass of 4.18 g. What are the masses of copper and silver metals in tile strip (Hint Remember that the copper metal is being used up as silver metal forms.)... 

Bipyridyl (Bipy) is a molecule commonly used as a bidentate ligand. When 0.17 mol of bipyridyl is dissolved in 2.4 L of a solution that contains 0.052 M Fe2+, [Fe(bipy)3]2+ (K[ = 1.6 X 1017) is formed. What are the concentrations of all species when equilibrium is established ... 

Throughout the main text of this book standard solutions and quantities have all been expressed in terms of molarities, moles and relative molecular masses. However, there are still many chemists who have traditionally used what are known as normal solutions and equivalents as the basis for calculations, especially in titrimetry. Because of this it has been considered desirable to include this appendix defining the terms used and illustrating how they are employed in the various types of determinations. 

D.9 The following aqueous solutions are common laboratory acids. What are their names (a) HCl(aq) (b) H2S04(aq) ... 

What are the principal solute species present in an aqueous solution of (a) Nal (b) Ag2CO, (c) (NH4)3P04 (d) FeS04 ... 

---