tailieunhanh - Chemistry part 7, Julia Burdge,2e (2009)

Tham khảo sách 'chemistry part 7, julia burdge,2e (2009)', khoa học tự nhiên, hoá học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 136 CHAPTER 4 Reactions in Aqueous Solutions The qualitative terms concentrated and dilute are relative terms like expensive and cheap. Solutions preparation of solutions. Molarity can equally well be defined as millimoles per milliliter mmol mL which can simplify some calculations. Students sometimes have difficulty seeing how units cancel in these equations. It may help to write M as mol L until you become completely comfortable with these equations. Figure Two solutions of iodine in benzene. The solution on the left is more concentrated. The solution on the right is more dilute. Concentrated solution More solute particles per unit volume Dilute solution Fewer solute particles per unit volume Concentration of Solutions One of the factors that can influence reactions in aqueous solution is concentration. The concentration of a solution is the amount of solute dissolved in a given quantity of solvent or solution. Consider the two solutions of iodine pictured in Figure . The solution on the left is more concentrated than the one on the right that is it contains a higher ratio of solute to solvent. By contrast the solution on the right is more dilute. The color is more intense in the more concentrated solution. Often the concentrations of reactants determine how fast a chemical reaction occurs. For example the reaction of magnesium metal and acid Section happens faster if the concentration of acid is greater. As we will see in Chapter 13 there are several different ways to express the concentration of a solution. In this chapter we introduce only molarity which is one of the most commonly used units of concentration. Molarity Molarity or molar concentration symbolized M is defined as the number of moles of solute per liter of solution. Thus 1 L of a molar solution of glucose CgH Og written as M C6H 2O6 contains moles of dissolved glucose. Half a liter of the same solution would contain mole of dissolved glucose a milliliter of the solution