Calorimetry: Heat of Reaction CHEM 131L Post Lab Assignment help

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Question description

Include the following information at the top of the first page of your assignment:

Name:
Lab Partner Name: Lab Section Number: Experiment Title: Due Date:

GENERAL INSTRUCTIONS

The entire report should be typed (handwritten portions will NOT be graded). Please organize your report as shown below. You and your lab partner may not work together on the data analysis, or turn in the same work or answers to questions. If you need help with calculations, you may ask for help from your instructor or the tutoring center.

DATA & CALCULATIONS

  1. Part B:

    1. Show typed calculations for the following values: mhot, ∆Thot, qhot, mcool,

      ∆Tcool, qcool, qcal, ∆Tcal, and Ccal.

    2. Create a table of just the calculated values listed above, displaying each value with proper units, mathematical sign and correct number of significant figures.

  2. Part C:

    1. Show one set of typed calculations for the following values: msoln, ∆Tsoln, qsoln, qcal, qneut, mole of the limiting reactant and molar qneut. If you performed multiple trials, only show calculations for one trial.

    2. Create a table of just the calculated values listed above, displaying each value with proper units, mathematical sign and correct number of significant figures. If you performed more than one trial, report the values for all trials in this table, as well as the average molar qneut.

QUESTIONS – All answers should be typed and given in complete sentences unless otherwise indicated.

  1. If some of the hot water evaporated during the heating process in part B, would that cause the calculated value of Ccal to be too large, too small, or unchanged in magnitude? Explain your reasoning.

  2. Write the chemical equation for the reaction in part C and give the molar heat of reaction. Based on the data, is the reaction in part C exothermic or endothermic? Explain your answer. As part of your answer, explicitly state from where and to where the heat flowed during the reaction.

  3. For each of the following components from part C, indicate whether they are part

of the a. b. c. d. e. f.

system or the surroundings. Styrofoam cups Thermometer Hydrochloric acid Sodium hydroxide

Water from the sodium hydroxide solution

Water product from the reaction

4. Give two possible sources for error that might have occurred during part C. Your answer cannot be based on just ‘human’ error (examples: calculation error, not following directions). Instead think about how the experimental set-up might lead to error. 

DATA:

Part B:

80 degrees C -hot water

59.3 degrees C -hot and cold water mixed

24.3 degrees C - cold water

45 mL styrofoam cup

80 mL heated beaker

Part C:

.996M HCl

1.10 M NaOH

51 mL NaOH @ 24.6 degrees C

46 mL HCl @25.5 degrees C

NaOH and HCl mixed 31.4 degrees C


Tutor Answer

strongboss5
School: New York University

Dear Depthy,Please find enclosed a doc file with the data analysis, calculations and the answers to the different questions.Since the main objective is that you understand and learn how to solve this kind of problems on your own next time, I would advise you to go through them carefully and come back to me in case you have any doubts so that we can clarify them. Thus, I would gladly answer any questions you might have regarding this assignment.Kind regards,Carmen

DATA & CALCULATIONS
Part B:
1. Show typed calculations for the following values: mhot, ∆Thot,

qhot, mcool, ∆Tcool, qcool, qcal, ∆Tcal, and Ccal.
2. Create a table of just the calculated values listed above, displaying each value
with proper units, mathematical sign and correct number of significant figures.

In order to solve part B you should consider that there is an equilibrium such that the heat of
hot water is transferred to cold water and the calorimeter walls.
Considering that heat transfer can be calculated as:
Q = mass * Specific heat * Variation of temperature
and the process involved, we can establish the equation:
Q (hot water) = Q (cold water) + Q (calorimeter)
m (HOT) * Ce (water) * ∆T (HOT) = m (COLD) * Ce (water) * ∆T (COLD) + m (cal) * Ce (cal) * ∆T (cal)
where as you see I simply substituted each heat term by the corresponding formula with its
specific parameters.
According to the data of your laboratory results we know:
Hot water: 85.0 mL at 79 ºC
Cold water: 50.0 mL at 24.6 ºC
Final equilibrium temperature: 58.2 ºC
Calculation of the mass of water (valid for both mhot and mcool):
In order to calculate the mass we will apply the formula:
mass = density * Volume
where we can assume the density of both cold and hot water is equal to 1 since the
experimental error will be greater than the one resulting from not considering the density
correction for different temperatures.
Thus, we find:
m(hot) = 1 g/ml * 85.0 g/ml = 85.0 g
m (cold) = 1 g/ml * 50.0 ml = 50.0 g

Calculation of the variation of the temperature (valid for both ∆Thot...

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