Show:
CH 6: Intermolecular Forces
CH 7: Stoichiometry
CH 8: Solutions
CH 9: Thermochemistry
Miscellaneous
100
The molecules in a sample of solid SO2 are attracted to each other by what intermolecular forces?
London dispersion forces AND dipole-dipole interactions
100
How many moles are in a sample of 43.5 g Ag?
0.403 mol Ag
100
Which of the following correctly matches the compound with its solute properties? A. Ca(OH)2 is a weak electrolyte B. C12H22O11 is a strong electrolyte C. NaCl is a non-electrolyte D. HNO3 is a strong electrolyte
D! HNO3 is a strong acid! A is a strong base or a strong electrolyte B is a non-electrolyte C is a ionic so it is a strong electrolyte
100
Which of the following is NOT a state function? Volume, work, temperature, internal energy
Work!
100
Define molarity! When do we use molarity?
Molarity is mol/liter We use this when dealing with aqueous solutions!
200
Which of the following has the strongest intermolecular forces? N2, NH3, H2O, or C2H4
H2O! It exhibits London forces, dipole-dipole, and hydrogen bonding
200
Balance the following equation. What is the coefficient of H2O? ____Al4C3 + ____H2O --> ____Al(OH)3 + _____CH4
12 Balanced coefficients are 1,12,4,3.
200
What is the net ionic equation for the reaction of AgNO3 (aq) + KCl (aq) ?
Net ionic = Ag+ (aq) + Cl- (aq) --> AgCl (s) NO3- and K+ are both spectator ions that exist as ions on each side of the equation.
200
Consider a rxn where heat is released. Is this reaction endothermic or exothermic? Are bonds formed or broken?
Exothermic, bonds are formed!
200
What is the % yield equation? What does each part mean?
% yield = (actual / theoretical) x 100 Actual = experimental Theoretical = calculated from chemical equation
300
Rank the following forces from weakest to strongest: Dipole-dipole, London Dispersion forces, Ionic bonding, ion-dipole, metallic bonding, and hydrogen bonding.
London dispersion forces < dipole-dipole < hydrogen bonding < ion-dipole < metallic < ionic
300
What is the percent by mass of carbon in caffeine, C8H10N4O2?
49.48% 8C = 96.088g total mass of caffeine = 194.193 96.088 / 194.193 x100 = 49.48% C
300
All of the following are precipitation reactions EXCEPT: A. Ba(NO3)2 + CaSO4 B. Na2S + AgNO3 C. MgSO4 + Zn(NO3)2 D. AgNO3 + NaCl
C. This produces no reaction because all products are soluble following double displacement. A-BaSO4 will ppt B-Ag2S will ppt D-AgCl will ppt
300
The heat of formation of O2 (solid) is... A. positive B. negative C. zero D. not enough info to determine
B. forming a solid = making bonds = exothermic = -enthalpy
300
In an expansion reaction, what sign is ∆V? What sign is w? Is work being done on the system or the surroundings?
∆V is + w is - Work is being done on the surroundings BY the system
400
Which will have the higher boiling point? NH3 or PH3?
NH3!
400
Adipic acid contains 49.32% C, 43.84% O, AND 6.85% H by mass. What's the empirical formula?
C3O2H5 C --> 4.106 mol / 2.74 (lowest) = 1.5 O --> 2.74 mol / 2.74 (lowest) = 1 H --> 6.796 mol / 2.74 (lowest) = 2.5 Need to multiply all by 2 to get whole numbers...Gives us C3O2H5
400
225 mL of a 1.88 M solution of NaCl (solution 1) was diluted to 500 mL to form solution 2. A 100 mL portion of this solution was removed and diluted further to 750 mL to form solution 3. What is the molarity (concentration) of NaCl in solution 3?
0.1128 M Use M1V1 = M2V2! (1.88)(225) = (M2)(500) Molarity of solution 2=0.846M (0.846)(100) = (M2)(750) Molarity of solution 3=0.1128M
400
If q=20 kJ and w=15kJ at constant pressure, which of the following statements is true? (Given ∆E=q+w) A. Heat flows from the system to the surroundings B. The system does work on the surroundings C. ∆E = 35 kJ D. All of the above
C. a positive w value = work done ON the system by surroundings a positive q value = system gains heat
400
Consider a beaker of pure water and a swimming pool of pure water. Which of the following are true about the water in each case? I. They have the same heat capacity II. They have the same molar heat capacity III. They have the same specific heat capacity
II and III are true! I is false. molar heat capacity = heat needed to raise temp of 1 mol of substance by 1 degree C specific heat capacity = heat needed to raise temp of 1g by 1 degree C
500
Arrange the following compounds by increasing melting point (lowest --> highest): NaCl, BCl3, MgCl2, PCl3
BCl3 < PCl3 < NaCl < MgCl2
500
What mass, in grams, of hydrogen is produced from the reaction of 4.73 g of Mg with 1.83 g of H2O? Mg + 2H2O --> Mg(OH)2 + H2
0.102 g H2O is the limiting reagent, which is necessary information to solve this problem. 0.102 mol of H2O are used up, and using the mole to mole ratio, we then know that HALF of that (0.051 mol) of H2 is formed in the products. Using molar mass, 0.051 mol of H2 equals 0.102g of H2.
500
A 0.303g sample of formula MCl2, where M is an unknown cation, reacts with excess AgNO3 to yield 0.783g of AgCl. What is the identity of M? MCl2 + 2AgNO3 --> M(NO3)2 + 2AgCl
M is Ca (calcium)! 0.783g AgCl / 143.32g AgCl = 0.00546 mol AgCl produced. Using the mole to mole ratio, MCl2 used should be 1/2 the moles of AgCl produced, therefore 0.0027 moles of MCl2 are used. Molar mass = grams/mol Molar mass = 0.303g/0.0027mol = 110.92g/mol 110.92g - 71(mass of 2 Chlorines) gives about 40 g which is the mass of calcium!!!!
500
In general, which of the following situations would you expect the system to absorb the largest amount of energy? (given w=-P∆V A. Temp of surroundings increases, volume of system contracts. B. Temp of surroundings increases, volume of system expands. C. Temp of surroundings decreases, volume of system contracts. D. Temp of surroundings decreases, volume of system expands.
C rxn should be endothermic to absorb heat (∆H = +) If work is done on the system, ∆V needs to be negative.
500
A rxn takes place in a flexible container initially at 298K and volume of 3.00L. This rxn causes the volume to decrease and the container's temperature to drop to 272K. What are the signs of both enthalpy (∆H) and work (w) in this rxn?
∆H = + w = + THE CONTAINER IS THE SURROUNDINGS! heat is lost from the container, so heat is entering the system. Endothermic! Volume decreases, so work was done ON the system by the surroundings, meaning w is positive.