Chem Exam: Types of Calculation Questions & Answers 100% Verified

Chem Exam: Types of Calculation Questions & Answers 100% Verified Calorimetry Calculations: 1. 2.50 kJ of energy changes the temperature of a sample of lead by 8.52 degrees C. What is the mass of the sample? - ANS-Q = mcΔT m=Qc/Δt m = 2500/0.13(8.52) = 2.3×103 g 2. 950.3 J of energy is removed from 28.5 g of water at 80.3 degrees C. What is the final temperature? - ANS-Q = mcΔT −950.3 = 28.5(4.18)(T2 − 80.3) T2 = −950.3/(28.5)(4.18) + 80.3 = 72.3O C 3. A 30.56 g sample metal is heated to 105.0 degrees C. It is then placed in 325 g of water at 25.2 degrees C in a calorimeter. The temperature of the water increases by 3.50 degrees C. What is the specific heat capacity of the metal? - ANS-−Qhot metal =Qcolder water [−mc(T2 −T1)] metal = [mc(T2 −T1)] water Enthalpy of Vaporization/Fusion: 1. 212.5 J of energy is required to vaporize 0.250 g of ethanol (C2H6O). Calculate the molar enthalpy of vaporization of ethanol. - ANS-USE FACTOR LABEL Enthalpy of Solution: 1. 12.5 g of CaCl2 (MM = 111.0 g/mol) is dissolved in 120.0 g of H20. The temperature of the water increases by 2.77 oC. Calculate the molar enthalpy of solution of CaCl2. - ANS-−nΔH ×1000 = mcΔT mL of water = - ANS-g of water Enthalpy of Combustion: Combustion formula - ANS-CxHx + O2 --> CO2 + H2O Enthalpy of Combustion: 1. The molar enthalpy of combustion of methane is -1895.0 kJ/mol. What mass of methane (MM = 16.0 g/mol) must be burned to raise the temperature of 200.0 mL of water by 2.50 degrees C? - ANS-−n ΔH ×1000 = mcΔT Enthalpy of Neutralization The molar enthalpy of neutralization is - 56.0 kJ/mol of water formed. 0.850 g of Mg(OH)2 (MM = 58.3 g/mol) is added to 250.0 mL of 0.150 M HCl. Calculate the change in temperature of the solution. Assume that the density and specific heat capacity of the solution is the same as that of water and that the volume of the solution remains at 250.0 mL. - ANS-−n ΔH ×1000 = mcΔT Enthalpy of Reaction: How much energy is released when 5.00 g of aluminum reacts with excess HCl according to the following reaction. - ANS-ΔH= kJ/mol rxn kJ = ΔH (mol rxn) kJ =5.00 g Al × mol/27 g × 62 kJ/2 mol Al = 5.74 kJ Hess's Law - ANSEnthalpy of Formation: Calculate the enthalpy of combustion of methane using the enthalpy of formation equations for methane (DH = -74.81 kJ/mol), water (DH = -285.83 kJ/mol), and carbon dioxide (DH = -393.51 kJ/mol). - ANSEntropy & Gibbs Free Energy: 1. Does calcium carbonate spontaneously decompose at 200.0OC? - ANS