Introduction: The objective of this experiment was to determine the heat of reaction of mixtures consisting of HCl, H2SO4, and CH3CO2H with NaOH and to find out how these reactions were related to one another thermochemically. Measuring heat of reaction and understanding what factors may affect it has been important in the creation of heating and cooling packs, which have been used in medicine to relieve pain and reduce muscle tension. Thermochemistry has been defined as the study of the changes in energy that accompany chemical reactions.1 One of the basic concepts in thermochemistry has been the distinction between the system (the focus of a thermochemical study) and its surroundings which are both part of a universe.1 One of the properties of a system is its internal energy (E), whose change has been expressed in the equation: E=q+w (where E is the change in internal energy, q is the heat transferred to or from the system, and w is the work done on or by the system).2 If the pressure is constant, then the heat (q) has also been defined as enthalpy (H). In most cases, the amount of work done on or by the system has been insignificant meaning the total energy change of a reaction would be equal to the change in enthalpy of reaction ( E=qrxn= Hrxn).2 The heat of reaction ( Hrxn) can be determined by using the equation: q=mC T (where m is the mass of the system, C is the heat capacity or the amount of energy required to raise the temperature of 1.00 g of a substance by
In order to measure the heats of reactions, add the reactants into the calorimeter and measure the difference between the initial and final temperature. The temperature difference helps us calculate the heat released or absorbed by the reaction. The equation for calorimetry is q=mc(ΔT). ΔT is the temperature change, m is the mass, c is the specific heat capacity of the solution, and q is the heat transfer. Given that the experiment is operated under constant pressure in the lab, the temperature change is due to the enthalpy of the reaction, therefore the heat of the reaction can be calculated.
When the volumes of NaOH and CH3COOH were equal, the temperature increased by 5 degrees celsius. When we performed a second trial and added 15 mL of NaOH and 5 mL of CH3COOH, the temperature only showed an increase
Hypothesis: If the temperature (I.V.) of materials in the reaction are increased, the reaction time (D.V.) will decrease.
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The law of thermodynamics in can predict the direction of chemical reactions and changes in substances
Chemical reactions that absorb energy are called endothermic reactions, these reactions are observed by a decrease in temperature of the reaction mixture.
Purpose: To utilize a calorimeter correctly to find the enthalpy changes in two different reactions. The purpose was also to use concepts of specific heat to observe the relationship between temperature observations and heat transfer. Then, use the equations to see the relationship between change in energy and the amount of substance involved. Use Hess’ law to determine the change in energy.
The literature value for the enthalpy change of the last reaction which was provided by our teacher is -97 kJ mol-1. Agreeing this value, our result can be considered accurate.
was too fast to measure and so for my scale to reach above that, I
This experiment was performed to determine the heat of neutralization between Hydrogen chloride (HCl) and Sodium hydroxide (NaOH). A temperature probe was used to measure the temperature of the reaction when the base (NaOH) was poured into the acid (HCl). The data was collected on logged on LoggerPro.
Introduction: The theory behind this experiment is the heat of a reaction (∆E) plus the work (W) done by a reaction is equal to
Heat is a form of energy that is transferred between two substances at different temperatures. The flow of the energy is from the object of higher temperature to the object of lower temperature. The heat is measured in units of energy, usually calories or joules. Temperature on the other hand, is how cold or hot an object is. The temperature is the average kinetic energy per molecule of a substance. This is measured in degrees on the Celsius or Fahrenheit or in Kelvins.
Background: Energy changes occur in all chemical reactions; energy is either absorbed or released. If energy is released in the form of heat, the reaction is called exothermic.
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.