Heat of Combustion of Magnesium
Hypothesis: Hess’s law states that “the enthalpy change for the conversion of reactants to products is the same whether the conversion occurs in one step or several steps” (DiGiuseppe et al,2012,p.314 ). A series of two experiments will perform in this lab in order to find ΔH1 and ΔH2 . In addition, ΔH3 will be obtained by reference. It is predicted that the combustion of magnesium will have a negative enthalpy, since combustion is an exothermic reaction. Also the sum of these three equations will be the net equation, and ΔHc can be determined by the addition of ΔH1 , ΔH2 , and ΔH3.
Discussion/Evaluation
Conclusion: When compared my calculation based on the data that were collected in the experiment (-824 kJ) to the theoretical heat of combustion of magnesium, which is (-601.9kJ). My result is off my by 37.4 %, 12& of error is due to equipment and 25.4% of error is due to procedure.
The hypothesis was only partially upheld because many errors occurred in equipment and procedure. 12 % of errors occurred as random errors, it would be the measuring equipments. When measuring the weight of magnesium oxide powder, magnesium , and hydrochloric acid the scale fluctuated slightly. As a result, the weight of the substances that were measured is slightly off to their actual values. Since, the mass of the …show more content…
The errors are said to be systematic errors. First of all, the procedure says that “insert Styrofoam cups into a beaker and obtain a lid”. We just assumed that the Styrofoam cups acted as isolated systems, which means they are completely sealed no heat comes out or into the system. However, this is incorrect since no energy conversions is 100% efficient and some heat will be lost to the environment in an exothermic reaction. This explains the unusual low change in enthalpy in ΔH1 that we
Hypothesis: Hess’s law states that “the enthalpy change for the conversion of reactants to products is the same whether the conversion occurs in one step or several steps” (DiGiuseppe et al,2012,p.314 ). A series of two experiments will perform in this lab in order to find ΔH1 and ΔH2 . In addition, ΔH3 will be obtained by reference. It is predicted that the combustion of magnesium will have a negative enthalpy, since combustion is an exothermic reaction. Also the sum of these three equations will be the net equation, and ΔHc can be determined by the addition of ΔH1 , ΔH2 , and ΔH3.
Discussion/Evaluation
Conclusion: When compared my calculation based on the data that were collected in the experiment (-824 kJ) to the theoretical heat of combustion of magnesium, which is (-601.9kJ). My result is off my by 37.4 %, 12& of error is due to equipment and 25.4% of error is due to procedure.
The hypothesis was only partially upheld because many errors occurred in equipment and procedure. 12 % of errors occurred as random errors, it would be the measuring equipments. When measuring the weight of magnesium oxide powder, magnesium , and hydrochloric acid the scale fluctuated slightly. As a result, the weight of the substances that were measured is slightly off to their actual values. Since, the mass of the …show more content…
The errors are said to be systematic errors. First of all, the procedure says that “insert Styrofoam cups into a beaker and obtain a lid”. We just assumed that the Styrofoam cups acted as isolated systems, which means they are completely sealed no heat comes out or into the system. However, this is incorrect since no energy conversions is 100% efficient and some heat will be lost to the environment in an exothermic reaction. This explains the unusual low change in enthalpy in ΔH1 that we