CHM110H5 Lecture Notes - Lecture 1: Acid Strength, Enthalpy, Titration

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14 Apr 2016

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Heat lost by hot water = vh cp. = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) (33. 145-41. 4) k. Heat absorbed by cold water = vc cp. = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) (33. 145-25. 4) k. | heat absorbed by the system| = | heat lost by hot water| - | heat absorbed by cold water| = 13. 76 j k-1 qp of neutralization of strong acid. Heat absorbed by acid = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) 6. 529 k. Heat absorbed by base = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) 5. 929 k. |heat absorbed by the system| =|heat absorbed by acid| +| heat absorbed by base| = 2603. 8 j qp of neutralization of weak acid. Heat release by reaction a = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) 6. 166 k. Heat release by reaction b = (50ml) (1. 00g ml-1) (4. 18 j g-1 k-1) 7. 766 k.

Related Questions

A student determined the calorimeter constant for a calorimeter and found from a plot of the time-temperature data that Tinitial of the 100.0 g sample of hot water was 30.10oC and of the 100.0 g sample of cold water was 20.72oC and the Tfinal of the mixture was 25.05oC.

Using the data provided in the excel file, show all of your work for the following calculations:

a.) heat transferred from hot water (J)

b.) heat transferred to cool water (J)

c.) calorimeter constant (J/K or J/oC)

A student reacted 100.0 mL of 0.9800 M HCl with 100.0 mL of 0.9900 M NH3. The density of the reaction mixture was 1.02 g/mL and the heat capacity was 4.016 J/g K. Calculate the enthalpy of neutralization by plotting and using the data shown below.

Time(min) Temp(oC)

0.0 23.25

0.5 23.27

1.0 23.28

1.5 23.30

2.0 23.30

3.0 23.35

4.0 23.44

4.5 23.47

mix ---------

5.5 28.75

6.0 28.50

7.0 28.55

8.0 28.48

9.0 28.32

10.0 28.25

11.0 28.20

12.0 28.05

13.0 27.96

14.0 27.80

15.0 27.75

Using the data provided in the excel file, show all of your work for the following calculations:

a.) mean temperature of unmixed reagents (oC)

b.) Î´ÎµÎ»ÏÎ±T from graph (oC)

c.) q absorbed by reaction mixture (J)

d.) q absorbed by calorimeter, stirrer, and thermometer (J)

e.) q total absorbed (J)

f.) q total released (J)

g.) calculation to show limiting reagent

h.) deltaH neutralization for the reaction (kJ/mole of acid)

A student determined the calorimeter constant of the calorimeter. The student added 50.00 ml of cold water to 50.00 ml of heated distilled water in a Styrofoam cup the initial temperature pf the cold water was 21.00 degrees Celsius and of the hot water 29.15 degrees Celsius the maximum temp of the mixture was found to be 24.891 degrees C the maximum temp of the mixture was found to be 24.81 Celsius assume the density of water is 1.00 g ml-1 and the specific heat is 4.184 J g-1 K-1.

1) Determine the ?T for the hot water and the cold water; calculate the heat lost by the hot water; calculate the heat gained by the cold water; Calculate the calorimeter constant, using the ?T of the cold water.

1. Complete and balance the following chemical reaction: NH4NO3(s) + H2O(l) --> ?

Given

2. Volume of DI water used 50 mL

3. Mass of DI water 50 g

4. Initial temperature of water, Ti 22.5Â°C

5. Mass of NH4NO3 3.0 g

6. Moles of NH4NO3 ________0.0375__________mol

7. Final temperature of water, Tf 18.9Â°C

8. change in temperature of the water (?T) -3.6 Â°C

9. calculate the heat associate with water, qH2O ___ ___-752.4_____________ J

m*c* deltaT = (50g)(4.184 J/g*k)(-3.6) = -752.4

10. the heat either released or absorbed by the reaction (?Hrxn) ________+752.4____________ J

Question: [Please notice the units]

11. Calculate the change in enthalpy (?Hrxn) for this reaction. _____________ kJ ??

12. Calculate the heat of reaction in kJ per mole of NH4NO3 ______________ kJ/mol ??

13. If the heat capacity of the calorimeter was 25 J/oC, what would the new change in enthalpy (?Hrxn) for this reaction be? (Use equation 7 to recalculate the value from #10) ____________________ kJ/mol ?? [Equation 7: - q(rxn) = q(soln) + q(calorimeter)

14. Is this an exo- or endothermic reaction? Explain the reasoning behind your choice. ??

15. Calculate the change in enthalpy for the reaction (?Hrxn) per mole using equation 8 and Table 2. NH4NO3 (s) --> NH4NO3 (aq)

__________________kJ/mol ?? [Equation 8: ?H_rxn = sum{ n?H_f (products) - sum{ n?H_f (reactants)

16. What is the percent error between your value and the value calculated from 13? What are some possible sources of error in the experiment?

__________________% error

CHM110H5 Lecture Notes - Lecture 1: Acid Strength, Enthalpy, Titration

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