• 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

    As shown on the graph, R2 (the correlation coefficient) equals to 0.5751, indicating that the data was not very reliable since the value was away from 1. In addition, the data points did not spread out, i.e., they were gathering at 0.004 to 0.006 moles. Consequently, the gradient was influenced.

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

    + 0.0001 =27.9850g Mass of MgO inside crucible with lid in grams after �heating to constant mass`=28.2125g Processed Data: Percentage uncertainty= 0.04% 1.Mass of magnesium (in grams) + 0.0001= 0.3450g (The mass of magnesium ribbon = The mass of the crucible, lid and magnesium- mass of the crucible and lid)

  1. IB chemistry revision notes

    OXIDATION AND REDUCTION Redox Reactions * Oxidation--> is the loss of electrons in a substance. o An oxidising agent is one that readily oxidises other substances. By doing so it gets reduced. * Reduction-->is the gain of electrons in a substance.

  2. hess's law

    sulphate was heated, its color changed from bright blue to white signifying the loss of water which indicates the formation of anhydrous copper (II) sulphate. Upon heating the anhydrous copper (II) sulphate, the slight temperature rise caused to beaker to become hot.

  1. Thermodynamics: Enthalpy of Neutralization and Calorimetry

    -2141.598 cal -2099.297 cal -2435.453 cal Moles of NaOH neutralized .1 mol .1 mol .1 mol Enthalpy of neutralization of NaOH kcal/mol -30.65 �.072 kcal -21.42 kcal/mol -20.99 kcal/mol -24.36 kcal/mol Enthalpy of neutralization of NaOH kJ/mol -128.24 �. 072 kJ/mol -89.604 kJ/mol -87.835 kJ/mol -101.90 kJ/mol Heat Capacity of

  2. 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)

  1. 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

  2. Discovering the formula of MgO

    Processed data: Raw Data Processed data Serial No. Mass of Magnesium(g)±0,001g Mass of crucible without lid(g)±0,001g Mass of crucible with product(g)±0,001g Mass of product(g)±0,002g Mass of oxygen(g)±0,003g Percentage composition of oxygen (%) Percentage error (%) 1 0,058 10,864 10,954 0,090 0,032 35,5 11,1 2 0,101 10,864 11,027 0,163 0,062 38,1 4,90 3 0,086 10,864 11,002 0,138 0,052 37,6

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