1A Fall20 Online Lab Specific Heat PDF

Preview

Summary

Download 1A Fall20 Online Lab Specific Heat PDF

Description

Specific Heat Simulation Lab Purpose: To determine the specific heat capacity of a mystery metal using calorimetry. Reading: Silberberg 8th edition Chapter 6, section 3 OR https://openstax.org/books/chemistry2e/pages/5-2-calorimetry

Introduction Calorimetry is a method that monitors heat exchange between a system (a chemical rxn, solid object, etc) and the surroundings (water). Since energy is conserved in the transfer between system and surroundings, two sets of heat equations can be set to equal and opposite of one another as seen in equation 1. Equation 1.

qsystem =-qsurroundings

msys ×Csys ×∆Tsys =-(msur ×Csur ×∆Tsur ) Heat will flow from the hotter object to the cooler object until thermal equilibrium is reached and both objects are the same temperature. By recording the masses of substances used and monitoring the temperature changes we can solve for the specific heat of the unknown substance.

Procedure 1. Go to http://media.saplinglearning.com/priv/interactive-books/intro-chem/specificheat/index.html. 2. First you will practice with one of the known metals. Pick one of the known metals (Ag, Au, Fe or Cu) from the drop-down menu in the upper right. 3. Record the mass of the metal by placing the metal on the balance. 4. Record the mass of the empty cup. 5. Fill the cup with water by clicking on the water dropper and then record the mass of the cup+water. 6. Record the initial temp of the water by dragging the thermometer into the water. 7. Heat the metal by clicking on the green button on the Bunsen burner. Record the initial temperature of the metal by dragging the thermometer over the metal. 8. Record the final temperature of the metal+water mixture. 9. Calculate the experimental specific heat for the metal you chose and then calculate the percent error. If the value is greatly different than the actual value then you made a calculation error. Go back and find correct your error. 10. Repeat steps 1-8 for the mystery metal.

Name:______________ Table 1: Recorded Measurements Trial 1 Metal used________

Trial 2 Unknown Metal

Mass metal (g) Mass cup (g) Mass cup+water (g) Initial temperature of H2O (C) Initial temperature of metal (C) Final Temperature (C)

Table 2: Calculations Trial 1 Metal used________

Trial 2 Unknown Metal

mwater (g) Twater (C) Tmetal (C) qwater (J) Cmetal (J/gC) % error

𝑞𝑤𝑎𝑡𝑒𝑟 = 𝑚𝑤𝑎𝑡𝑒𝑟 × 𝑐𝑤𝑎𝑡𝑒𝑟 × ∆𝑇𝑤𝑎𝑡𝑒𝑟 where cwater = 4.184 J/gC 𝐶𝑚𝑒𝑡𝑎𝑙 =

−𝑞𝑤𝑎𝑡𝑒𝑟 𝑚𝑚𝑒𝑡𝑎𝑙 × ∆𝑇𝑚𝑒𝑡𝑎𝑙

Table 3: Specific Heat values for various metals Metal Gold 0.1256 Specific Heat (J/gC)

Copper 0.3768

Iron 0.4605

Silver 0.2386

Name:______________

Questions 1. Think about carrying out the experiment in person and list two specific sources of error that occur do to experimental design. Simply listing “user error” is not a valid source of error.

2. What is the definition of specific heat capacity?

3. An aluminum kettle weighs 1.05 kg and has a heat capacity of 0.9211 J/g °C. a. How much heat is required to increase the temperature of this kettle from 23.0 °C to 99.0 °C?

b. How much heat is required to heat this kettle from 23.0 °C to 99.0 °C if it contains 1.25 L of water (density of 0.997 g/mL and a specific heat of 4.184 J/g °C)? Hint: the total heat is additive.

4. How much will the temperature of a cup (180 g) of coffee at 95 °C be reduced when a 45g silver spoon (specific heat 0.24 J/g °C) at 25 °C is placed in the coffee and the two are allowed to reach the same temperature? Assume that the coffee has the same density and specific heat as water....