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.
Procedure: Refer to pages 67-76 of General Chemistry 1210: General Chemistry Laboratory Manual by the Department of Chemistry, The Ohio State University, Hayden-McNeil Publishing, 2016.
Data/ Results: See attached report sheets
Sample Calculations:
Value of heat capacity
〖-(q〗_cu+q_water)=q_calorimeter
q=C_s*m*ΔT q_water=58.7150g*4.18J/(g*˚C)*7.9˚C q_calorimeter=-(-1950+1938)=12.0
Molar enthalpy of neutral
ΔH_1=q_rx1/moles=-65800J/mole
-q_rx1=q_HCl+q_NaOH+q_calorimeterl=1870J+59.5J+90J=2000J
Heat of rxn of Mg2+ and acid
-q_rx1=q_Soln+q_calorimeter=2270J+122J=2390J
ΔH3 ,
Mg(s) + 2H+(aq) →Mg2+(aq) + H2(g) 65.8kj/mole
〖〖2H〗_2 O(l)→2H〗^+ (aq)+〖2OH〗^- (aq) -362kj/mole
Mg(s) + 2 H2¬O(l) → Mg2+(aq) + 2OH¬-(aq)+ H2(g) -296kj/mole
ΔH4
Mg2+(aq) + 2OH¬-(aq)+ H2(g) →Mg(s) + 2 H2¬O(l) 296kj/mole
Mg(s) + O2(g) +H2(g) →MgOH2(s) -924.7kj/mole
2H2O(l) → 2H2(g) + O2(g) 571.6kj/mole
Mg2+(aq) + 2OH¬-(aq) →MgOH2(s) -57kj/mole Discussion/ Conclusions: The lab used methods of calorimetry in order to measure the temperature change of reactions and calculate the changes in
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.
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.
11. Use the equation: q = m(SH)ΔT to solve for the specific heat of the metal.
2. How did concentration and/or volume differences affect the heat change (q) for each trial?
We can assume that the specific heat capacity of water is 4.18 J / (g × °C) and the density of water is 1.00 g/mL.
CHE 133 Experiment 3, General Chemistry II Lab, Spring Quarter 2014-2015, DePaul University. [Online] https://www.d2l.depaul.edu (accessed April 25, 2015)
Koczanski, Krystyna; Xidos, James D. CHEM 1300 Laboratory Manual; UMSU Copy Centre: Winnipeg, MB, Canada, 2013, pp
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.
Farrell, R. M., Metcalfe, J. S., McGowan, M. L., Weise, K. L., Agatisa, P. K., & Berg, J.
We will be using 6 different fuels to heat up 100ml of water, and find out the changes of the temperature. We will measure the temperatures of the water before and after the experiment. We will burn heat the water for exactly 2 minutes, and check the changes in temperature. The change in temperature will allow us to work out the energy given off the fuel by using this formula:
The styrofoam cups were used to store the acid (cup was labeled A) and base (cup was labeled B) prepare for them to be mixed. A lid was put on cup A and then the temperature probe was inserted to begin to measure the temperature
Introduction: The theory behind this experiment is the heat of a reaction (∆E) plus the work (W) done by a reaction is equal to
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.
When lighting a candle, one does not ruminate about how the candle flame is an exothermic process. In actuality, there are endothermic and exothermic reactions happening all around at various times. Before proceeding, one should know that exothermic reactions are ones in which energy is released. They can be discerned by reaction giving off heat, such as the example of the candle flame expelling vapor. Endothermic reactions are reactions where energy is absorbed. One can detect an endothermic reaction by, for example, touching a beaker in which a reaction occurs that becomes cool. The changes in temperature, both endothermic and exothermic, lead to the idea of enthalpy. This is defined as the difference between the potential energies of products from reactants, and is shown as ΔH. When a reaction produces heat the value for enthalpy will be negative, and when it's absorbed it will be positive. The relationship of the transfer of heat between the system and surroundings can be used to determine the enthalpy change reaction by using the equation q=mCΔT. This can be accurately measured by using the process of Calorimetry. This is a method to measure heat by observing the temperature change when a body absorbs or discharges energy as heat. It is useful since it insulates the reaction, and the only measurable change will originate from the water in the reaction. The spontaneity of a reaction depends on the values for enthalpy, entropy, and Gibbs free energy. Entropy is the
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.