Learning Log Unit 2 You must show all calculations with units

1) WE HAVE STUDIED THREE TYPES OF NET IONIC EQUATIONS IN AQUEOUS SOLUTION: formation of a precipitate, formation of a weak electrolyte or non electrolyte, and the formation of a gas (CO2, SO2, H2S) . These are all metathesis reactions. Write two examples of a precipitate forming, one example of a weak electrolyte, one example of a non electrolyte, and an example of each type of gas that could be produced from a double displacement reaction.

2) OXIDATION-REDUCTION REACTIONS: Use the copper and nitric acid reaction to explain redox reactions. Include in your description how to determine what is oxidized, what is reduced, what is the oxidizing reagent, and what is the reducing reagent.

3- Pure acetic acid is a liquid with a density of 1.049 g/ml at 25 C. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 ml of acetic acid in enough water to make 250.0 ml of solution.

4- A solution of 100.0 ml of 0.200 M potassium hydroxide is mixed with 200.0 ml of 0.150 M nickel sulfate. (a) write the balanced equation (b) What precipitate forms? (c) what is the limiting reactant? (d) How many grams of precipitate form? (e) What is the concentration of each ion remaining in solution? (f) What is the color of the final solution?

5- The reaction of aluminum powder with iron(III) oxide is highly exothermic and is known as the thermite reaction. The reaction is used for welding propellers on ships. Using the enthalpies of formation from appendix C , calculate Ho for the reaction.

6- Complete combustion of 1 mol of acetone (C3H6O )liberates 1760 kJ of heat energy. Using this information and the values from appendix C, calculate the enthalpy of formation of acetone.

7- When a 9.55 g sample of sodium hydroxide is dissolved in 100.0 g of water in a coffee cup calorimeter, the temperature rises from 23.6 C to 47.4 C. Calculate H ( in kJ/mol of sodium hydroxide) for the solution process. Assume the specific heat of the solution is the as pure water ( 4.184 j/gm-K)

8- From the following:

H2(g) + F2(g) 2HF(g) H= -537 kJ

C(s) + 2F2(g) CF4(g) H= -680 kJ

2C(s) + 2H2(g) C2H4(g)H= +52.3 kJ

Calculate H for the reaction:

C2H4(g) + 6F2(g)  2CF4(g) + 4HF(g)

9- Suppose you have a solution that might contain any or all of the following cations Ni 2+, Ag1+, Sr2+, and Mn2+. Addition of HCl solution causes a precipitate to form. After filtering off the precipitate, H2SO4 solution is added to the resultant solution and another precipitate forms. This is filtered off and a solution of NaOH is added to the remaining solution. No precipitate is observed. Write net ionic equations for the two precipitate reactions. (You can assume that when a ppt forms all of the cations that are involved are removed from the solution). Which of the four ions listed above must be absent from the original solution? Explain your reasoning.

10- Chloromycetin is an antibiotic with the formula C11H12O5N2Cl2. A 1.13 grams of a solution containing chloromycetin was chemically treated to convert its chlorine into chloride ions. The chloride ions were precipitated with lead ions to form lead (II) chloride. If it took 8.54 mL of a 0.150 M lead (II) nitrate what is the mass of chloride in the ointment? What is the mass of Chloromycetin? What is the % chloromycetin in the solution?

11- A 2.035 g organic compound containing carbon, hydrogen, and oxygen was burned in excess oxygen gas releasing 4.162 g of carbon dioxide and 1.291 g of water. The molecular mass of the compound is 172.0 g/mol. a) What is the empirical formula? b) What is the molecular formula? c) How many grams of oxygen gas were used to oxidize the original 2.035 grams of compound?

12- substance Hf (kj/mol) substance Hf (kj/mol) H2O (l) -286 O2 (g) 0.00 CO2 (g) -393 C3H8(g) ??????

o When 1.000 g of propane gas (C3H8 ) is burned at 25 C and 1.00 atm, H2O (l) and CO2 (g) are formed with the evolution of 50.3 kj of heat. (Evolved means heat is released so this is an exothermic reaction (-50.3 kj) a) Write a balanced equation for the combustion reaction. b) Calculate the molar enthalpy of combustion (∆ H of combustion) o c) Calculate the standard heat of formation of propane gas ( ∆ H f ) Write a correctly balanced equation for the formation of propane gas from its elements.

13- The following data was collected in an enthalpy experiment in which magnesium was reacted with excess HCl.: Mass of HCl = 101.50 grams, mass of Mg = 0.50g, Initial Temperature = 22.68oC , Final Temperature = 47.16o C. (Use 4.18 j/g.oC for dilute solutions of HCl) a) Calculate the heat transferred in the calorimeter b) Determine the heat of reaction for 1.00 mole of Magnesium o o o c) ∆ H f of MgO= -602 kj/mol ; ∆ H f of MgCl2 = -642kj/mol Calculate the ∆ H f of HCl