LAB: Specific Heat of a Metal

Prelab question:

Metal SpecificHeat

(J/g ºC)

Aluminum 0.91

Iron 0.46

Lead 0.13

Silver 0.23

Tin 0.21

Titanium 0.54

Zinc 0.39

A calorimeter containing 100.0 mL of room-temperature water (23.2 C) warms up to 48.1C when a 225 g sample of unknown metal is placed inside. The initial temperature of the metal was 100.0 C.

a) What is the specific heat of this metal?

b) Identify this metal from the list of possibilities in Figure 1.

Table 1: Specific Heats of Metals

Prelab question:A calorimeter containing 100.0 mL of room-temperature water (23.2 C) warms up to to 48.1C when a 225 g sample of unknown metal is placed

inside. The initial temperature of the metal was 100.0 C.

a) What is the specific heat of this metal?

Tmetal = Tf-Ti = 48.1C – 100.0C = -51.9C

mmetal = 225 g

Twater = Tf-Ti = 48.1C - 23.2C = 24.9C

g 100.0mL 100.0

mL 1cm 1

cm

g 1m

3

3water

Prelab question:A calorimeter containing 100.0 mL of room-temperature water (23.2 C) warms up to to 48.1C when a 225 g sample of unknown metal is placed

inside. The initial temperature of the metal was 100.0 C.

a) What is the specific heat of this metal?

qcal = mwatercwater ∆Twater

qcal = (100 g)(4.18 J/gC)(24.9 C)qcal = 10,408.2 J

qrxn = -10,408.2 J-10,408.2 J = (225g)(c)(-51.9C)c = 0.891 J/gC

Prelab question:

A calorimeter containing 100.0 mL of room-temperature water (23.2 C) warms up to to 48.1C when a 225 g sample of unknown metal is placed inside. The initial temperature of the metal was 115 C.

b) Identify this metal from the list of possibilities in Figure 1.

cexperimental=0.891

The sample must be aluminum.

Metal SpecificHeat

(J/g ºC)

Aluminum 0.91

Iron 0.46

Lead 0.13

Silver 0.23

Tin 0.21

Titanium 0.54

Zinc 0.39

Table 1: Specific Heats of Metals

In groups, write procedures for this lab. Do not start the lab until your procedures have been approved by your instructor.

MATERIALS:• Beaker, 600 mL• Boiling stones• Crucible tongs• Graduated cylinder, 100-mL • Hotplate • Metal (bolt or sinker)• Styrofoam cups (2)• Thermometer

PURPOSE:

To determine the specific heat of an unknown metal and use this value to identify the unknown metal when given a list of possibilities

Sample procedures:1. Add a few boiling stones and 250-mL of tap

water to a 400-mL beaker; heat the water until the water is boiling gently using the hot plate (DO NOT turn the hot plate to max. DO STEP 2 WHILE WAITING FOR WATER TO BOIL

2. Obtain a piece of metal from your teacher and write the DESCRIPTION in your data table (ex. Bolt or the Sinker).

3. Record the mass of your metal.4. Using tongs, carefully place your metal in

the water that is gently boiling on the hot plates. Allow the metal to heat up for 5-10 minutes. Continue to the next steps while you wait.

5. Setup a makeshift calorimeter using 2 styrofoam cups (one as the base, one as the top, which has a small hole in the top for the thermometer).

6. Measure 75.0-100.0 mL of cool distilled water in a graduated cylinder and pour this water into your calorimeter. Record the exact amount (nearest 0.1 mL) as the mass of your water (since the density of water = 1.0 g/mL, the volume = mass. EXAMPLE, 50.0 mL = 50.0 grams of water).

7. Measure the temperature (to ONE DECIMAL PLACE) of the water in the calorimeter. Record this as the initial temperature of the water in your data table.

8. Check the thermometer of the hot water bath and record this temperature (to ONE DECIMAL PLACE) as the initial temperature of the metal.

9. DO THIS STEP QUICKLY: Using tongs, remove metal from hot water and immediately place it in the calorimeter.

10. Monitor the temperature of the water in the calorimeter. Carefully use the thermometer to gently stir the water. Record the highest temperature (to ONE DECIMAL PLACE) as the final temperature of the metal and as the final temperature of the water in your data table

11. Remove the metal from the cup, dry the metal, and repeat the trial 2 more times.

12. Clean your designated lab area, return all materials, and check in with your teacher before returning to your desks.

What will you turn in?• Each group will turn in their procedures.

• Each individual will turn in the following:– Data table(s): clearly

organized/labeled/etc. – Calculations:

• Determine specific heat of sample – Show all work & round to SF at end– All numbers must have units

• Identify metal• Percentage error

– Discussion/conclusion: discuss a minimum of 3 sources of error and explain how each would affect your overall result (Ultimately, how might each error affect your calculated specific heat value?)

Metal SpecificHeat

(J/g ºC)

Aluminum 0.91

Iron 0.46

Lead 0.13

Silver 0.23

Tin 0.21

Titanium 0.54

Zinc 0.39

Table 1: Specific Heats of Metals