Pre-Laboratory Assignment 1. Read an authoritative source for a discussion of th

Question

Pre-Laboratory Assignment 1. Read an authoritative source for a discussion of the safe and proper way to insert a thermometer or glass tubing into a rubber stopper. Read an authorita- tive source for a discussion of graphing techniques (2) Calculate T for the reaction. Assume the ini- tial temperature of both reactants is 250 2. A student doing this experiment was puzzled by the fact that while each of the individual solutions being used is dangerous, the mixture made by combining the two solutions is much less dangerous. Actually, the re- sulting mixture could be safely disposed of by pouring t into the drain and diluting with a large amount of run- ning water. Describe the hazards of each of the solu tions. Explain why the mixture is not as hazardous as the original solutions from a waste-disposal point of view (3) Calculate the volume of the reaction mixture. (4) Assume the density of the mixture is 1.03 g Calculate the mass of the reaction mixture. of the mixture is 1.03 g ml- (5) Calculate the heat transterred from the reac- tion of 50.0 mL of 1.00MHNO3 with 50.5 mL of 1.00M NaOH solution. Assume the heat capacity of the miox- ture is 3.89 Jg deg- 3. A student determined the eutzn of nitric acid (HNO3) mixed with NaOH solution, using the proce- dure described in this experiment. Fifty milliliters of 1.00M HNO3 was added to 50.5 mL of 1.00M NaOH cting when 50.0 mL of 1.00M HNO solution, and the following time-temperature data 1.00M NaOH solution are mixed. were recorded. (6) Calculate the number of moles of HNO re- and 50.5 mL of time, min temp, °C 24.7 24.8 time, m in 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 temp. °C 31.2 (7) Calculate Hneutzn in joules per mole for the reaction of 1.00 mol of HNO3 with 1.00 mol of NaOH. 31.0 30.9 30.8 30.7 4.0 30.2 31.2 31.5 31.5 31.4 31.2 31.2 30.5 30.4 (8) on the basis of an accepted Areutzn of 58.5 kJ mor1 for the reaction, determine the percent errorin 10.0 your calculated Heutzn. (1) Make a plot of these time-temperature data.

Explanation / Answer

2)T=Tf-Ti   =30.3 C-25 C=5.3C   tf=final temperature,ti=initial temperature

3)volume of the reaction=50 ml+50.5ml=100.5ml

4)mass of the reaction mixture=density*volume=1.03g/ml*100.5ml=103.5 g

5)heat transferred=mass of mixture*heat capacity of mixture*T=103.5 g*3.89 J/g C*5.3C=2123.55J=2.123 KJ

6)no of moles of HNO3=molarity of HNO3*volume of HNO3=1.00 M*50ml=1.00 mol/L*0.050 L=0.050 moles

7)Hneut=heat transferred =2123.55 J

Moles of mixture =0.050 moles HNO3+0.050 mol of NaOH=0.1 mol

Hneut=2123.55 J/0.1 mol=21235.5 J/mol of reaction mixture=21.235 KJ/mol

8) Hneut(theoretical)=58.5 KJ/mol

%error=Hneut(theoretical)- Hneut(calculated)/ Hneut(theoretical)*100=(52.5-21.23/58.5)*100=63.7%

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