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

experiment Hess Law

Extracts from this document...

Introduction

Name : Mohd Haziq Al-Hakim Bin Hamirruddin Class : M08F Date : 9 July 2009 Practical : 16 Data Collection and Processing Part A:- Mass of magnesium ribbon = 0.2836 � 0.0001g Volume of 0.5 M of HCl = 50.0 � 0.5 cm3 Reactant Initial Temperature, � 0.5�C Highest Temperature, � 0.5�C Mg + HCl 27.0 40.5 Table 1 shows the initial and highest temperature for reaction between Mg and HCl To calculate the change in temperature, the following equation will be used:- Reactant Change in Temperature, � 1.0�C Mg + HCl 13.5 Table 2 shows the change in temperature for reaction between Mg and HCl Equation for part A:- Mg (s) + 2HCl (aq) --> MgCl2 (aq) + H2 (g) Mole of magnesium Mole of hydrochloric acid = mass = MV RMM 1000 = 0.2836 g = 50.0x0.5 24.3 1000 = 0.0118 mol = 0.025 mol Thus, ...read more.

Middle

30.0 Table 3 shows the initial and highest temperature for reaction between MgO and HCl To calculate the change in temperature, the following equation will be used:- Reactant Change in Temperature, � 1.0�C MgO + HCl 2.0 Table 4 shows the change in temperature for reaction between MgO and HCl Equation for part B:- MgO (s) + 2HCl (aq) --> MgCl2 (aq) + H2O (l) Mole of magnesium oxide Mole of Hydrochloric acid = mass = MV RMM 1000 = 0.4985g = 50x0.5 (24.3+16) 1000 = 0.0124 mol = 0.025 mol Thus, the limiting reagent is magnesium oxide Calculation: Heat change, Q = mc?T = 50g � 4.2 Jmol-1�C-1 � 2 �C = 420 J ?Hrxn = -420_ 0.0124 = -33.87 kJmol-1 Uncertainties: Mass = = 1.0 % Temperature = = 50.0 % No of mole = = 8.1% Total = 59.1% ?Hrxn = -33.87 kJmol-1 � 59.1 % Since the reactions are exothermic, the ?Hrxn for each reaction is negative. ...read more.

Conclusion

+ 2HCl(aq) � MgCl2(aq) + H2(g) ?Hrxn = -240.25 kJmol-1 � 9.25% MgCl2(aq) + H2O(l) � MgO(s) + 2HCl(aq) ?Hrxn = +33.87 kJmol-1 � 59.1% Mg(s) + H2O(l) � MgO(s) + H2(g) ?Hrxn = -206.38 kJmol-1 � 68.35% ?Hrxn = -206.38 kJmol-1 � 16.12 % For the theoretical value: 1. Mg(s) + (g) MgO(s) ?Hrxn = -601.8 kJmol-1 2. H2(g) + (g) H2O(l) ?Hrxn = -285.8 kJmol-1 By reversing equation 2: 3. H2O(l) H2(g) + (g) ?Hrxn = +285.8 kJmol-1 The theoretical value of the reaction, equation 1 + equation 3: Mg(s) + (g) MgO(s) ?Hrxn = -601.8 kJmol-1 H2O(l) H2(g) + (g) ?Hrxn = +285.8 kJmol-1 Mg(s) + H2O(l) MgO(s) + H2(g) ?Hrxn = -316.0 kJmol -1 ?Hrxn obtained from this experiment = -206.38 kJmol-1 The theoretical value of ?Hrxn = -316.0 kJmol -1 Percentage error = Theoretical value - Experimental value Theoretical value = = 34.69% Reference: Chemistry: A Central Science by Brown, Le May and Bursten ...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. Experiment - The Empirical Formula of Magnesium Oxide

    the reactions were not fully completed; 2) the readings of the masses were incorrect since it took a while for the electronic balance to reach the real mass. Thus, if the experimenter did not wait till the readings stopped changing; the recorded data would be smaller than they were supposed to be. These could cause random errors.

  2. Lab Experiment : The change in mass when magnesium burns. (Finding the empirical formula ...

    5.Simplest ratio: Mg = 0.0142Mole = 1 0.0142Mole Oxygen = 0.0142mole = 1 0.0142mole The ratio of Mg to O is therefore 1:1 The empirical formula of Magnesium Oxide found for this is MgO CONCLUSION AND EVALUATION Conclusion: The weight of the product (MgO)

  1. Hess's Law. The experiment conducted was meant to determine the enthalpy of formation of ...

    MgCl2(aq) + H2O(l) --> MgO(s) + 2HCl(aq) 101.5 � 0.5 Mg(s) + 2HCl(aq) --> H2(aq) + MgCl2(aq) - 366.1 � 0.4 H2(g) + 1/2O2(g) --> H20(l) - 285.8 Table VII: Enthalpy of Formation of MgO Original Equation Enthalpy of Formation (kJ/mol)

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

    and magnesium metal strip Trial 1 Trial 2 Trial 3 Mass of magnesium metal strip (mMg) (0.25 + 0.01)g (0.25 + 0.01)g (0.25 + 0.01)g Volume of 1.0 mol/L hydrochloric acid solution (vHCl) (50 + 1)cm3 (50 + 1)cm3 (50 + 1)cm3 Initial temperature of hydrochloric acid solution (Ti)

  1. hess's law

    Controlled Variables: The volume of distilled water used i.e. 50 cm3 was kept constant by using a measuring cylinder to measure the volume, the temperature and pressure at which the experiment was conducted was also kept constant by conducting the experiment from the beginning till the end in the same room and the room temperature was monitored and the

  2. Thermodynamics: Enthalpy of Neutralization and Calorimetry

    Another 50 mL of distilled water are measured, put onto a heating plate until it reaches 65 C�, taken off, allowed to rest until the temperature stops rising (this temperature is taken), and then added to the calorimeter. The solution and the water are stirred for two minutes and then

  1. Enthalpy and Hess law

    Then using a measuring cylinder 50 ml of 2M of HCl was measured and poured into a can. A thermometer was used to record the temperature of the hydrochloric acid in the can. Afterwards NaOH was added into the can.

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

    Same thermometer has been used for all the temperature readings. Ruler Different rulers have different systematic and random errors. Same ruler is used to measure all the strips of magnesium strip. Time interval between each reading of temperature If readings are taken inconsistently, maximum temperature might be incorrectly determined because

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