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EXPERIMENTAL METHODS A. Qualitative Studies to Identify Hot versus Cold In your

ID: 554590 • Letter: E

Question

EXPERIMENTAL METHODS A. Qualitative Studies to Identify Hot versus Cold In your lab notebook, t 1. Obtain a test tube for each salt. Place about S to 6 mL D.I. water into each test tube. 2. Using a scoopula, transfer about 2-cm length of salt on the scoopula into the test tube prepare a table similar to Table 12.2 (this does not need to be weighed). Mix the contents with a stirring rod, and touch the test tube to the palm of your hand. Record the temperature change as warmer (heat released). cooler (heat absorbed), or no change. If you are unable to detect a change, you may want to repeat the procedure with a temperature probe. 3. Repeat this procedure for each salt in your set. Obtain the results for the sets that your team did not perform from other teams, and record your observations in your notebook. Also compare your results with any other teams repeat the tests if you want to confirm your results. the same salts. You may B. Quantitative Studies for Hot Pack (exothermic) Salts 4. Pick one of the hot pack salts from your results to study the quantitative heat measurements. You will utilize a Styrofoam calorimeter (see Figure 12.1). which is useful for measuring heat changes. In your notebook, prepare a table for collecting time and tempera- Temperature Probe ture readings similar to Table 12.3. 5. Record the mass of a coffee cup and place it in a ring stand so that it will not tip over. Add approximately 25 mL of room temperature deionized water to the cof- fee cup and determine the total mass. 6. Use the temperature probe to stir the FIGURE 121 Calorimeter Made from a Styro- solution. Support the cup with a ring stand so that it will not tip over. foam Cup . Record the temperature of the water in the calorimeter with the La bQuest swirling con- tinuously. Record the temperature just before adding the salt. This will be your initial temperature.

Explanation / Answer

salt

formula

price

Environmental considerations from SDS

GHS designation

Most likely issue for our situation

Production or disposal issues

references

Ammonium chloride

NH4Cl

Given

short term degradation products are not likely. Chronic hazards to aquatic environment

Irritant, hazardous to environment

Harmful if swallowed and causes eye irritation

Dilute with water and flush to sewer

The SigmaAldrich Library of Chemical Safety Data, Edition II. -Hawley, G.G.. The Condensed Chemical Dictionary, 11e ed., New York N.Y., Van Nostrand Reinold, 1987. Manufacturer's Material Safety Data Sheet

Sodium nitrate

NaNO3

Given

short term degradation products are not likely long term products may form

Slightly Explosive when heated, strong oxidiser

Mutagenicfor humans, reproductively harmful for males

none

Sciencelab.com for msds

Magnesium sulfate

MgSO4

Given

Long term degradation occurs and The products of degradation are more toxic.

irritant

Harmful if swallowed and irritant on eyes and skin contact

none

National Institute for Occupational Safety and Health

Calcium chloride

CaCl2

Given

Ecotoxicity in water (LC50): 100 mg/l 96 hours [Fish].

irritant

Harmful for respiratory tract on ingestion, skin and eye contact and harmful if swallowed

none

Sciencelab.com for msds

salt

formula

price

Environmental considerations from SDS

GHS designation

Most likely issue for our situation

Production or disposal issues

references

Ammonium chloride

NH4Cl

Given

short term degradation products are not likely. Chronic hazards to aquatic environment

Irritant, hazardous to environment

Harmful if swallowed and causes eye irritation

Dilute with water and flush to sewer

The SigmaAldrich Library of Chemical Safety Data, Edition II. -Hawley, G.G.. The Condensed Chemical Dictionary, 11e ed., New York N.Y., Van Nostrand Reinold, 1987. Manufacturer's Material Safety Data Sheet

Sodium nitrate

NaNO3

Given

short term degradation products are not likely long term products may form

Slightly Explosive when heated, strong oxidiser

Mutagenicfor humans, reproductively harmful for males

none

Sciencelab.com for msds

Magnesium sulfate

MgSO4

Given

Long term degradation occurs and The products of degradation are more toxic.

irritant

Harmful if swallowed and irritant on eyes and skin contact

none

National Institute for Occupational Safety and Health

Calcium chloride

CaCl2

Given

Ecotoxicity in water (LC50): 100 mg/l 96 hours [Fish].

irritant

Harmful for respiratory tract on ingestion, skin and eye contact and harmful if swallowed

none

Sciencelab.com for msds

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