chemistry

Experiment 1Determination of Specific Heat of a Metal

Experiment Inventory

Materials 2 Styrofoam™ 8 oz. Cups

Styrofoam™ 8 oz. Cup Lid

Unknown Metal

*Camera/Smart Phone

*Stove-Top or Microwave

*Tap Water

*Wooden Toothpick (if using a microwave)

Labware 100 mL Graduated Cylinder

500 mL Glass Beaker

Test Tube Clamp

Thermometer

Scale

*Hot Pad

*Cooking Pot

*Stopwatch / Clock

*Paper TowelsNote: You must provide items listed in *red.

EXPERIMENT 1: DETERMINATION OF SPECIFIC HEAT OF A METAL

In this experiment, you will measure and record the temperature over time to determine the specific heat and identity of an unknown metal.

PROCEDURE

1. Put on your safety glasses and gloves (Provided in your safety box)

2. In a cooking pot add 500 mL of tap water, place on the stovetop and bring the water to a boil. Set a stopwatch for 3 minutes. Once it has boiled for three minutes, reduce the heat from a boil to a simmer. (See Figure 11).

Note: If you do not have a stove, heat the 500 mL of water to boiling in a microwave safe container. To avoid the risk of superheating water (water that does not look boiling, but explodes when agitated), place a microwave safe object in the water and heat the water at 1 minute increments (such as a wooden toothpick). At the end of every minute, tap the microwave safe container before removing the container from the microwave to test if your water is superheated. Superheated water can be extremely dangerous and may cause serius burns. Use extreme caution if using the microwave method to boil water. Once boiling, carefully remove the container using the provided insulated glove.

3. Using your 100mL graduated cylinder measure 50 mL of room temperature tap water into one of the Styrofoam™ cups.

Figure 11: Sample set-up for Step 1. A pot with 500 mL of water rests on a stove-top burner.

©2018, eScience Labs

4. Record the mass of the water in Table 2.

5. Put the two Styrofoam™ cups together by placing the Styrofoam™ cup containing 50 mL of room temperature tap water inside the empty Styrofoam™ cup.

6. Place your cups upright inside of the 500 mL beaker. The beaker is used to provide vertical support for the Styrofoam™ cups. (See figure 12)

7. Turn on the scale by pressing the button labeled 0/T. If your scale does not turn on, you may have to remove the battery cover and remove a small strip of plastic from the battery housing. Once the scale is on, press the 0/T button a second time to zero the scale. Make sure that the units are in grams (g). If not, press the M button until the units displayed are in grams. Pick up your unknown metal and place it on the scale. Record the weight of the unknown metal in Table 2.

8. Make sure that your metal will not protrude above the water level; if necessary you may need to carefully bend or cut it. Insert the thermometer into the hole in the lid. This apparatus is your calorimeter.

9. Put your insulated glove on over your safety glove, then pick up the unknown metal strip with the test tube clamp and hold the clamp and unknown metal in the simmering water for five minutes to ensure that the clamp and metal reach the same temperature as the water.

Hint: Do not drop the unknown metal into the pot of hot water and leave it there. It will be difficult to retrieve the heated metal from the hot water and any attempt to do so could cause severe burns.

10. After five minutes has passed, quickly transfer the hot unknown metal into the calorimeter. Remember to quickly replace the lid with the thermometer in it. Be careful to ensure that the thermometer is not touching the metal, only the water.

11. In Table 3, record the temperature of the water after five minutes has passed, every minute for five additional minutes. Gently swirl the contents of the cup right before recording the temperature.

12. Repeat Steps 1 - 10 two more times. Calculate the average heat capacity of the unknown metal. Begin by calculating q for water then use that information to calculate heat capacity for the metal.

13. Use Table 1 as a reference for determining your unknown metal.

Figure 12: Sample set-up for Step 6.

©2018, eScience Labs

Data Sheet Experiment 1 Data Sheet

Table 2: Mass

Mass (g)

Water

Unknown Metal Strip

Table 3: Specific Heat Data

Time (minutes) Temperature (°C)

Trial 1 Trial 2 Trial 3

Initial

5 minutes

6 minutes

7 minutes

8 minutes

9 minutes

10 minutes

Average Specific Heat Capacity of the Unknown Metal:

©2018, eScience Labs

Exercise 3 Experimental Variables

EXERCISE 3: EXPERIMENTAL VARIABLES

Identify the variables tested in each of the following experiments. If applicable, determine and identify any positive or negative controls. Submit this exercise to your instructor upon completion.

1. A study is being done to test the effects of habitat space on the survival of fish populations. Different sized aquariums are set up with six goldfish in each one. Over a period of six months, the fish are fed the same type and amount of food. The aquariums are equally maintained and cleaned throughout the experiment. The temperature of the water is kept constant. At the end of the experiment the number of surviving fish are surveyed.

a. Independent Variable:

b. Dependent Variable:

c. Controls:

2. To determine if the type of agar affects bacterial growth, a scientist cultures on four different types of agar. Five petri dishes are set up to collect results:

• One with nutrient agar and E. coli

• One with mannitol-salt agar and E. coli

• One with MacConkey agar and E. coli

• One with LB agar and E. coli

• One with nutrient agar but NO E. coli

a. Independent Variable:

b. Dependent Variable:

c. Controls:

© 2018, eScience Labs

Experiment 1Determination of Specific Heat of a Metal

Experiment Inventory

Materials 2 Styrofoam™ 8 oz. Cups

Styrofoam™ 8 oz. Cup Lid

Unknown Metal

*Camera/Smart Phone

*Stove-Top or Microwave

*Tap Water

*Wooden Toothpick (if using a microwave)

Labware 100 mL Graduated Cylinder

500 mL Glass Beaker

Test Tube Clamp

Thermometer

Scale

*Hot Pad

*Cooking Pot

*Stopwatch / Clock

*Paper TowelsNote: You must provide items listed in *red.

EXPERIMENT 1: DETERMINATION OF SPECIFIC HEAT OF A METAL

In this experiment, you will measure and record the temperature over time to determine the specific heat and identity of an unknown metal.

PROCEDURE

1. Put on your safety glasses and gloves (Provided in your safety box)

2. In a cooking pot add 500 mL of tap water, place on the stovetop and bring the water to a boil. Set a stopwatch for 3 minutes. Once it has boiled for three minutes, reduce the heat from a boil to a simmer. (See Figure 11).

Note: If you do not have a stove, heat the 500 mL of water to boiling in a microwave safe container. To avoid the risk of superheating water (water that does not look boiling, but explodes when agitated), place a microwave safe object in the water and heat the water at 1 minute increments (such as a wooden toothpick). At the end of every minute, tap the microwave safe container before removing the container from the microwave to test if your water is superheated. Superheated water can be extremely dangerous and may cause serius burns. Use extreme caution if using the microwave method to boil water. Once boiling, carefully remove the container using the provided insulated glove.

3. Using your 100mL graduated cylinder measure 50 mL of room temperature tap water into one of the Styrofoam™ cups.

Figure 11: Sample set-up for Step 1. A pot with 500 mL of water rests on a stove-top burner.

©2018, eScience Labs

4. Record the mass of the water in Table 2.

5. Put the two Styrofoam™ cups together by placing the Styrofoam™ cup containing 50 mL of room temperature tap water inside the empty Styrofoam™ cup.

6. Place your cups upright inside of the 500 mL beaker. The beaker is used to provide vertical support for the Styrofoam™ cups. (See figure 12)

7. Turn on the scale by pressing the button labeled 0/T. If your scale does not turn on, you may have to remove the battery cover and remove a small strip of plastic from the battery housing. Once the scale is on, press the 0/T button a second time to zero the scale. Make sure that the units are in grams (g). If not, press the M button until the units displayed are in grams. Pick up your unknown metal and place it on the scale. Record the weight of the unknown metal in Table 2.

8. Make sure that your metal will not protrude above the water level; if necessary you may need to carefully bend or cut it. Insert the thermometer into the hole in the lid. This apparatus is your calorimeter.

9. Put your insulated glove on over your safety glove, then pick up the unknown metal strip with the test tube clamp and hold the clamp and unknown metal in the simmering water for five minutes to ensure that the clamp and metal reach the same temperature as the water.

Hint: Do not drop the unknown metal into the pot of hot water and leave it there. It will be difficult to retrieve the heated metal from the hot water and any attempt to do so could cause severe burns.

10. After five minutes has passed, quickly transfer the hot unknown metal into the calorimeter. Remember to quickly replace the lid with the thermometer in it. Be careful to ensure that the thermometer is not touching the metal, only the water.

11. In Table 3, record the temperature of the water after five minutes has passed, every minute for five additional minutes. Gently swirl the contents of the cup right before recording the temperature.

12. Repeat Steps 1 - 10 two more times. Calculate the average heat capacity of the unknown metal. Begin by calculating q for water then use that information to calculate heat capacity for the metal.

13. Use Table 1 as a reference for determining your unknown metal.

Figure 12: Sample set-up for Step 6.

©2018, eScience Labs

Data Sheet Experiment 1 Data Sheet

Table 2: Mass

Mass (g)

Water

Unknown Metal Strip

Table 3: Specific Heat Data

Time (minutes) Temperature (°C)

Trial 1 Trial 2 Trial 3

Initial

5 minutes

6 minutes

7 minutes

8 minutes

9 minutes

10 minutes

Average Specific Heat Capacity of the Unknown Metal:

©2018, eScience Labs