Problem Set: Heat Calculations Practice

Name: PROBLEM SET: HEAT CALCULATIONS PRACTICE Period: SC5.ab and SC2.g I am learning about endothermic and exothermic processes. Can I differentiate between and give examples of endothermic and exothermic physical processes? Can define and calculate specific heat capacity (using 𝑞 = 𝑚𝑐∆𝑇). Can I define and calculate heat (enthalpy) of fusion and heat (enthalpy) of vaporization? Can I explain how a heating curve represents the effect of energy changes on intermolecular forces and phases? Can I analyze and interpret data and patterns in a heating curve? 1. Before 1982, pennies were made of pure copper, Cu, with a mass of 3.1 grams. (a) How much heat would be required to heat a penny from 21 oC to 84 oC? The specific heat capacity of Cu metal is 0.385 J/g-oC. (b) Fill in the LOL Chart and label where the process is happening on the heating curve. Make the penny the system. (c) This process is: [exothermic | endothermic]. (d) The [kinetic | potential | both] energy of the Cu atoms is [increasing | decreasing]. (e) Sketch a heating curve on the same graph for a metal with 𝑐 = 1.5 𝐽 but similar ∆𝐻𝑓𝑢𝑠 and ∆𝐻𝑣𝑎𝑝, g∙℃ boiling point, and melting point. VARIABLES: CALCULATIONS: ANSWER: 𝑞= 𝑚= 𝑐= 𝑇𝑓 = 𝑇𝑖 = ∆𝑇 = 2. 35.o grams of water (∆𝐻𝑓𝑢𝑠 = 333 𝐽) freezes at 0 oC to become an ice cube. g (a) How much heat did the water transfer to the freezer in the process? (b) Fill in the LOL Chart and label where the process is happening on the heating curve. Let’s make the water the system for this problem.. (c) This process is: [exothermic | endothermic]. (d) The [kinetic | potential | both] energy of the Cu atoms is [increasing | decreasing]. (e) Sketch a heating curve on the same graph for a new substance (not water) with smaller ∆𝐻𝑓𝑢𝑠 and ∆𝐻𝑣𝑎𝑝. lower boiling point and melting point, but similar 𝑐. (f) Would the substance in (e) have stronger or weaker inter-particle attractions (IMF)? VARIABLES: CALCULATIONS: ANSWER: 𝑞= 𝑚= ∆𝐻𝑓𝑢𝑠 = (f) Write a chemical equation for this process. Make sure to include the Joules of heat in the equation. . Armstrong — 5ab_2g -P- Heat Calculations Practice docx Name: Period: PROBLEM SET: HEAT CALCULATIONS PRACTICE SC5.ab and SC2.g 3. To find the energy in a pork rind, you burn it and calculate the heat transfer with a soda can calorimeter. The calorimeter has 275. grams of water (𝑐 = 4.18 𝐽 ). The initial temperature was 20.2 oC and the final g∙℃ temperature was 39.8 oC. The pork rind lost 0.97 grams of mass when burned. How much energy per gram is in the pork rind? Fill in the LOL Chart and label where the process is happening on the heating curve. Make the calorimeter water the system. VARIABLES: CALCULATIONS: ANSWER: 𝑞g𝑎𝑖𝑛𝑒𝑑 = −𝑞𝑙𝑜𝑠𝑡 ∆𝑚𝑝𝑜𝑟𝑘 𝑟𝑖𝑛𝑑 = 𝑚𝐻2- = 𝑐𝐻2- = 𝑇𝑓∙𝐻2- = 𝑇𝑖∙𝐻2- = ∆𝑇𝐻2- = 4. To find the specific heat capacity of a 42.3 gram piece of tin (Sn), you heat it in a beaker of water (at 96.3 oC) and drop it in a coffee cup calorimeter with 150. grams of water at 21.0 oC (𝑐 𝐻 0 = 4.18 𝐽 ). The final 2 g∙℃ o temperature (water + tin) is 22.3 C. What is the specific heat capacity, c, of the tin? Fill in the LOL Chart and label where the process is happening on the heating curve. Make the calorimeter water the system. VARIABLES: 𝑚𝑆𝑛 = 𝑐𝑆𝑛 = 𝑇𝑓∙𝑆𝑛 = 𝑇𝑖∙𝑆𝑛 = ∆𝑇𝑆𝑛 = 𝑚𝐻2- = 𝑐𝐻2- = 𝑇𝑓∙𝐻2- = 𝑇𝑖∙𝐻2- = ∆𝑇𝐻2- = CALCULATIONS: ANSWER: 𝑞g𝑎𝑖𝑛𝑒𝑑 = −𝑞𝑙𝑜𝑠𝑡 Name: Period: PROBLEM SET: HEAT CALCULATIONS PRACTICE SC5.ab and SC2.g 5. A 35.0 gram ice cube at –5.00 oC is dropped into 200. g of Coca-Cola at room temperature (20.0 oC). The ice cube melts, and the resulting temperature is 4.27 oC. Find the specific heat capacity of Coca-Cola. Ice at 0 oC ➝ Cool water Warm water ➝ Cool Coca-Cola For H2O: cice = 2.10 J/g-oC ; cwater = 4.18 J/g-oC ; csteam = 2.08 J/g-oC ; ∆𝐻𝑓𝑢𝑠 = 333 J/g ; ∆𝐻𝑣𝑎𝑝 = 2260 J/g Label the initial and final temperatures on each y-axis. Shade where the change occurs on and number the segment(s) (1), (2), etc. Heat gained in Segment 1: Heat lost in Segment 1: Heat gained in Segment 2: (If applicable) Heat lost in Segment 2: (If applicable) Heat gained in Segment 3: (If applicable) Heat lost in Segment 3: (If applicable) Total heat gained: Total Heat Lost: Label, with the ice as the system. Solve for ∆𝐻𝑓𝑢𝑠 to determine the enthalpy of fusion of water. Remember: q𝐺𝑎𝑖𝑛𝑒𝑑 = −q𝐿𝑜𝑠𝑡