• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

We measured the change of temperature of two reactions to determine the enthalpy change of the third. We first theoretically calculated the enthalpy and then performed experiments.

Extracts from this document...

Introduction

Shazde Mehkri 11/12/08 Enthalpy change of a chemical reaction Data: Runs Initial temperature +0.1 ?C Final temperature +0.1?C Change in temperature +0.2?C 1 22.74 36.27 13.53 2 21.57 23.36 1.79 3 22.47 35.53 13.06 Final temp. is calculated by ==> Y = mx + b For reaction1: 0.00648(11)+36.2 = 36.27 (See attached graphs) (Values of m,x & b are taken from graph) Sample calculations: Run 1: Change in Temp. = Final Temp. - Initial Temp. 13.53? C = 36.27? C - 22.74??C (Similar calculation done for Run 2 and Run 3) Data processing: Reaction 1:NaOH + HCL ==> NaCl + H2O Net ionic equation: H+ + OH- ==> H2O Theoretical H for reaction 1: -(H Products - H reactants) (-286 - (-230) ...read more.

Middle

Experimental Q = mc t For run 1:reaction between NaOH and HCL NaOH + HCL ==>H2O + NaCl M=D*V D=1.03gml-1 V=100ml M=1.03*100=103 g (Uncertainty for mass is +0.5g) C=4.184 J/?C T=13.53?C Q=5830.78 j =5.830 Kj Uncertainty is +0.014j (Similar calculations done for run 2 & 3) For run 2: reaction between NaOH + NH4CL ==> NH3 + H2O Q=0.771 Kj +0.11j {Q uncertainty is calculated by [uncertainty of temp/ change in temp]} Each solution were 2.0 molar Therefore moles= 0.050 L * 2mol/1 L =. 1 mol To show Hess's law: NaOH + HCL==> H2O NH3 + H2O ==> NaOH + NH4CL {the 2 reactions equation is flipped} In order to get: NH3 + HCL==> NH4CL H for run 1=Q/mol =5.830/0.1=58.3 Kj H ...read more.

Conclusion

We then compared our theoretical values with our experimental. All of the above mentioned steps were done to prove Hess's law. Some errors existed in our experiment. The % error that we calculated was about 2.85%. These possible errors were present because of not placing the temperature probe in its right position. The temperature probe should be placed in such a way that it should be touching the solution. If we placed our probe little lower in the solution then it was we could have eliminated the chance of such error. The mass should be measured using beakers rather than calculating it manually. This is done to increase accuracy. Also, equal time should be given to all reactions in order to generate heat. For this magnetic stirrers should be rotated at constant speed for all reactions. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Chemistry essays

  1. The Enthalpy of Neutralization

    x (4.18J�g-1�k-1) x (-12.25) = -2560J (-12 + -12.5) � 2 Conversion of Uncertainty to Relative Error [(Nearest unit of volume measurement observed � desired volume) x 100 = Percentage error of volume] (1�50) x 100= 2% [(Nearest unit of temperature measurement observed � recorded temperature)

  2. Determining an enthalpy change of reaction

    Temperature/?C 32 32 32 32 32 32 32 31.5 Trial 1 Time/s 0 30 60 90 120 150 180* 210 240 Temperature 22.5 22.5 22.5 22.5 22.5 22.5 25 29.5 30 Time/s 270 300 330 360 390 420 450 480 ?

  1. Hesss Law Lab, use Hesss law to find the enthalpy change of combustion of ...

    RU ( c) = 0 ( table value ) So percentage uncertainty for RU(Q)=RU(m)+ RU(?T) RU(Q) = 2+ 12.5 = +/- 14.5 % Now, the absolute uncertainty for MgO's mass is, AU(m(MgO))=+/-0.01 g Then RU(m(MgO))= (AU(m(Mg))/ m(Mg))*100% RU(m(MgO)) = (0.01/0.40)*100 = 1/0.40 = � 2.5 % As AU(M(Mg))=0 because this value is given and not calculated by us so, RU(n)

  2. Thermodynamics: Enthalpy of Neutralization and Calorimetry

    With this information, the following formula can be used to find the specific heat of the metal cylinder: (m �?T�s)metal = (m �?T � s)water + (Heat Capacity � ?T)calorimeter . To find the heat of neutralization between NaOH and NaCl, first two 2 M, 50.0 mL solutions are made for NaOH and NaCl respectively.

  1. The aim of this experiment is to examine the enthalpy of combustion of the ...

    56.5 Qualitative data No soot found on the boiling tube.The color of the flame was light orange. Incomplete transmission of heat is assumed due to the movements caused in the laboratory, which affected the flame and therefore the transmission. Qualitative data Mass of ethanol Mass 1 Mass 2 Mass 3

  2. To determine the standard enthalpy of formation of Magnesium Oxide using Hess Law.

    The container claimed to contain MgO with only trace amounts of impurities. Dependent Variables: 1. Maximum temperature reached: Temperature of the solution was recorded using the same thermometer each time so that no additional systematic errors are introduced. Controlled Variable Reason for controlling Method of Controlling Calorimeter Using different calorimeters

  1. Research question: how to convert NaOH to NaCl by two different routes , and ...

    50.00 cm3 of HCl is added to the solution. 3. Temperature of the solution is collected each 30 seconds . 4. The end product will be 100.0 cm3 of NaCl with the concentration of 1 mol dm-3 Route (B): 1.

  2. Analysis of the Standard Enthalpy of Combustion for Alcohols

    Volume of liquid used Measure 100cm3 of distilled water by using 100 cm3 ± 0.08 cm3 graduated pipette for each trial. If the volume was not exactly 100 cm3 it would directly affect the mass of the water which will affect the q=mcâT value and thus the âH value.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work