Lab Report 3 Chem.docx

EXPERIMENT 3 Calorimetry

Group 1 Sofia Isabelle G. Garcia CE-1

CM011/B8

REPORT The temperature change in the calorimeter will be unaffected by this technique error. The original specific heat of water is 4.18 J/g•°C, but if this value increases that means that water will take more energy to change the temperature. Therefore, an increase in the amount of water does not make a difference because the specific heat of water was also increased. More water means that the temperature of the water will decrease more because the mass increased. Because the temperature change is lower, assuming the mass is constant, the amount of heat must be lower. In measuring the specific heat of a metal, if one used the highest measured temperature for calculating the metal’s specific heat rather than the extrapolated temperature. The extrapolated temperature is used to determine the maximum temperature of the mixture rather than the highest recorded temperature in the experiment, which his decision will result in a higher specific heat value for the metal. The enthalpy of neutralization for all strong acid-strong base reactions should be the same within experimental error because Any neutralization reaction between a strong acid and strong base will result in the following net ionic equation: H+ + OH- = H20 (all the other ions in the equation are spectator ions and therefore are not in the net ionic equation). Because the overall reaction is always the same regardless of the acid or base, the enthalpy change will also be the same. If a weak acid is used, the enthalpy change will be less exothermic as some of the energy evolved will be cancelled out by the energy needed to complete the dissociation of the incompletely dissociated acid during the reaction. On the other hand, heat is lost to the Styrofoam calorimeter. Assuming a 6.22 C temperature change for the reaction of HCl (aq) with NaOH (aq), if we calculate the heat loss to the inner 2.35g Styrofoam cup. The specific heat of Styrofoam is 1.34 J/g C. The heat loss to the inner Styrofoam cup can be calculated as q=mspht∆T. After substituting the values into the equation, we get q= (2.35 g)(1.34 J/g•°C)(6.22°C)= 19.6 J. Therefore, 19.6 J of heat was lost to the inner Styrofoam cup. When one carelessly adds only 40.0 mL (instead of the recommended 50.0mL) of 1.1 M HCl to the 50.0mL of 1.0 m NaOH. The consequence of the error will be40ml HCl reacting with

50ml NaOH The mole ratio is 1:1 in reaction. Some of the NaOH would not react so (Change in H) would decrease. If ever a misscalibrated by a plus 2 Cover the entire thermometer scale was used. This factory error would carry through all experiments and have no effect because we are using (change in H). If some of the salt remains adhered to the weighing paper (and therefore is not transferred to the calorimeter), the enthalpy of solution would be reported as too low if some of the salt is not transferred to the calorimeter. This happens because the enthalpy of the solution is being measured with a lower mass instead of the original, entire mass. The dissolution of ammonium nitrate, NH4 NO3 in water is an endothermic process. Since the calorimeter is not a perfect insulator, the enthalpy of solution, the enthalpy of the solution for ammonium nitrate will be reported as too high if this heat change is ignored. The enthalpy will be too high because the calorimeter does not absorb all the heat. Since it does not absorb all the heat, more heat will have to be put into the system. Therefore, the enthalpy of the solution, ∆Hs, would be reported as too high.

CONCLUSION The conclusion of the experiment is that the styrofoam calorimeter can be acknowledged as a function tool. The results could be deemed slightly accurate as the values provided by the Styrofoam cup show similar readings to that of the commercial brand. However, there were moreinsulation than the commercial brand calorimeter, containing more heat from the data, the temperature was higher for the styrofoam than the commercial calorimeter. All it comes down to is human error such as not cutting the hole on the lid properly as it could release the heat energy more if the hole is too big. The effect of the use of styrofoam is an experiment is highlighted positively if other materials such as beaker and plastic cups were considered to be used in place of the styrofoam. The heat could escape more easily through the glass and to the holder’s hand if a beaker is used. Paper cups would be useless as well as it conducts heat.