Hess Law Lab Report

The main objective of this experiment is to differentiate between a physical change and a chemical change.

An Investigation into the Enthalpies of the Combustion of Alcohols = == == == ==

In this lab, there are two days. In the first day, there are is part A and part B. Part A is further divided into three experiments. In experiment one, we were to figure out the heat capacity of the calorimeter that we made. The next two experiment’s goal was to calculate the enthalpy of 2 reactions and using hess’s law, figure out the heat of formation of magnesium oxide. In a reaction, there are

    One possible source of error that can affect the results was that a mercury thermometer was used instead of an electronic one. The use of a mercury

Abstract: This two part experiment is designed to determine the rate law of the following reaction, 2I-(aq) + H2O2(aq) + 2H+I2(aq) + 2H2O(L), and to then determine if a change in temperature has an effect on that rate of this reaction. It was found that the reaction rate=k[I-]^1[H2O2+]^1, and the experimental activation energy is 60.62 KJ/mol.

This reaction is exothermic, meaning it releases heat when reactants are converted into products. The negative change in enthalpy (∆H° = -36,757 J) for this reaction indicates that the reaction is losing heat to its surroundings.

Enthalpy (H)- The sum of the internal energy and the pressure – volume product of a system H= E + PV.

In this week’s lab experiment, the rate of decomposition of hydrogen peroxide forming oxygen gas will be observed and studied. Since the rate of a chemical reaction is dependent on two things; the concentrations of the reactants and the temperature at which the process is performed, the rate can be measured at which a reactant disappears or at which a product appears. When measuring the rate, the rate law will be applied. The objective of this lab is to demonstrate how the rate changes with varying initial concentrations of hydrogen peroxide by measuring the rate at which oxygen is evolved.

Chemical reactions that absorb energy are called endothermic reactions, these reactions are observed by a decrease in temperature of the reaction mixture.

Determining how a mechanism comes to be is crucial as a scientist and arriving to conclusions is a crucial component which lead to examining and determining which mechanism takes place when two or more substrates are made to react. At the end of the experiment a mechanism was determined based on the purified product’s melting point. This was accomplished by having the reaction take place but also through acquiring the melting point and comparing the number to the melting point which was already established by the scientific community. (Q1) When 0.252 g of trans-cinnamic acid was mixed in 2.5 mL glacial acetic acid and 0.434g pyridinium tribromide was added, the resulting product reflects an addition reaction. In general, reactions take place to achieve its lowest Gibb’s free energy because it’s at

At the Left side of the equation, its show the energy (KJ/mole) taken in by the reaction,

This lab is performed in order to determine the total energy in a reaction between zinc and hydrochloric acid. The reaction is done twice, once to measure the heat of the reaction and again to determine the work done in the system. This is because Enthalpy equals heat plus work (∆H= ∆E+W). Heat and work can be broken down further into separate components so the equation used in lab is ∆H=mc∆T + PV. Many calculations are used in the lab to find out what cannot be measured directly (ex: volume). After all the calculations were complete it was shown to have a very small percent error.

The purpose of this lab was to test the law of conservation of mass by comparing the total mass of the reactants in a chemical reaction with the total mass of the product.

Purpose: This lab taught procedures for determining heat of capacity of a calorimeter and measuring enthalpy of change for three reactions. It also enforced methods of analyzing data obtained through experimentation and calculating enthalpy. These procedures are used in the branch of thermodynamics known as thermochemistry which is the study of energy changes that accompany chemical reactions. Concepts from this lab can be used to determine the potential energy of a chemical reaction. Much of the energy people depend on comes from chemical reactions. For example, energy can be obtained by burning fuel, metabolizing of food or discharging a batter.

Introduction: Every chemical change is accompanied by a change in energy usually in the form of heat. If heat is evolved, the reaction is exothermic, and if heat is absorbed, the reaction is endothermic. The energy change of a reaction that occurs at constant pressure is called the heat of reaction or the enthalpy of reaction (ΔHr). This quantity of heat is measured experimentally by allowing the reaction to occur in a calorimeter. In this experiment you will determine the heat of neutralization when an acid and a base react to form 1 mole of water. In a perfect calorimeter, heat is exchanged only between the reaction and the calorimeters water. Technically, some heat may may be absorbed the calorimeter. All calorimeters exchange some heat with its environment. This amount of heat is called the calorimeters heat capacity (the amount of of heat required to raise its temperature 1∘Celsius). We are going to “pretend” that our calorimeter is the perfect calorimeter.