Chem 1520 Exam: Types of Calculation Questions & Answers (100% Correct)

Chem 1520 Exam: Types of Calculation Questions & Answers (100% Correct) Chem 1520 Exam: Types of Calculation Questions & Answers (100% Correct) 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? - ANSWER - 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? - ANSWER - 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? - ANSWER - −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. - ANSWER - 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. - ANSWER - −nΔH ×1000 = mcΔT mL of water = - ANSWER - g of water Enthalpy of Combustion: Combustion formula - ANSWER - CxHx + O2 -- CO2 + H2O