CHE 2B Lecture 7: Chapter 17

Which of the following is true? When the yield of chemical reaction is less than 100%, this indicates one of the reactants is present in insufficient amount to react with the entire amount of another reactant. The reactant with the fewest number of moles is the limiting reactant reactant in chemical reaction. A mole ratio is a ratio between the number of moles of any two species involved in a chemical reaction. In a chemical reaction at least one reactant must be in excess for the reaction to complete. It is possible under some circumstances for the actual yield of a chemical reaction to exceed the theoretical yield. Which of the following is FALSE? A true solution cannot be cloudy. Both the solute and solvent in a solution may be a solid, a liquid, or a gas. The solute is the most abundant component of a solution. A solution is a homogeneous mixture. A solution can contain more than one solute and more than one solvent. yield is the calculated value predicting how much product is possible. yield requires me to leave the lecture hall, do the reaction, and weight the milliliters of0.525 M Na2CO3 solution, contains 25.0 g of Na2CO3

Heat of sublimation can be approximated by adding together, _and_- . A) heat of fusion, heat of condensation B) heat of fusion, heat of vaporization C) heat of freezing (solidification), heat of condensation D) heat of freezing (solidification), heat of vaporization E) heat of deposition, heat of vaporization 10hlaced n a contane of non, the agon pontaneoudies hrugbout tenceon because A) of the large attractive forces between argon and neon atoms B) of hydrogen bonding C) a decrease in energy occurs when the two mix Di the dispersion of argon atoms produces an increase in disorder E) of solvent-solute interactions 11) Formation of solutions where the process is endothermic can be spontaneous provided that A) they are accompanied by another process that is exothermic B) they are accompanied by an increase in order . D) the solvent is a gas and the solute is a solid E) the solvent is water and the solute is a gas 12) The principal reason for the extremely low solubility of NaCl in benzene (C6H6) is the Analyze: lonic compounds tend to form ion-dipole interactions being dissolved and dissociated. That is why are soluble in polar solvents. Benzene is non-polar, so solvation of Na and Cl- in it is weak. A) strong solvent-solvent interactions B) hydrogen bonding in C6H6 C) strength of the covalent bond in NaC DI weak solvation of Nat and Cby CGHs E) increased disorder due to mixing of solute and solvent 13) The concentration of CO2 in a soft drink bottled with a partial pressure of Co2 of 4.0 atm over th at 25℃ is 12x 1o-1 M. The Henry's law constant for CO2 at this temperature is Analyze: k can be calculated from Henry's law: S kP A1 3.0 x 10-2 mol/L-atm .

Experiment 10 Colligative Properties Introduction A pinch of wa make boiling water hotter. A handful will clear the snow from your steps. Every day we the physical properties of materials around us, but often don't know why we use these particular s or what chemistry is involved. Modifying the temperature of phase changes, by adding a second chemical to the pure solvent are examples of manipulating the Colligative Properties of a solution. this lab, we will study how varying the concentration and type of a salt affects the point of a solution. Colligative properties are properties of a solution containing 2 or more components. Typically, the primary is the solvent and the other called the such as color or hardness, properties depend on the number of particles of astute in the not the identity of the In many cases, the rokute will determine the number of solute particles (degree of ionization, solubility, etc,) in the solvent, but a colligative property does not depend upon the nature of the particles. Two colligative properties commonly encountered are boiling point elevation and freezing point depression (the temperature of of a is lower than of pure solvent). We will be studying boiling point elevation in this Most of the previous work that you have done with solutions has involved units of molarity, M, or moles of solute per liter of solution. Boiling point elevation calculations (as well as those for freezing point depression) or moles of solute per kilogram of solvent. boili change of temperature. When the temperature of a solution changes, the volume of the solution also changes. Since molarity depends on a change in wil the solution's molarity. Molality depends on the mass of the solvent. and thus is independent of temperature. n't Hoff Factor salt into and the of moles inorganic salts in an aque the based on the addition of the number dissociates, the total number of particles in the solution will be of cations and anions produced from the dissociation. Thus; Nacion Na Choaa (2moles of particles) Cacbrs Ca +2ch (3moles of particles) The quantity of particles produced per mole of solute is called the van'tHoff factor and is given the symbol, i, If 1 mole of sodium chloride were completely dissociated, iwould be 2. This theory works very well for dilute solutions and non-electrolytes (i 1, no dissociation at all since nonelectrolytes not ionize), For does not always apply to more concentrated solutions. Thus, when there are a large number of particles in a solution, they have a tendency to recombine as the salt and you don't get 100% dissociation. example, at a NaCl concentration of 0.1M, iwill be 1.81 (90% dissociation) rather than 2 (100%). Boiling Point Elevation solute causes the solution to boil at a higher When a solution is heated, the presence of a non-volatile point of the pure liquid and the temperature than the pure The difference between the boiling boiling point of the solution is: 169