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Haz-Cat Demonstration

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DEH HIRT Insignia

Identifying an Unknown Substance Using Haz-Cat

unknown solid

 

Start at the HazCat Unknown Solids Chart, Observations.
The top of the chart will look like this.

 

unknown solid test

 

The substance spilling from the bottle appears to be inert which leads to thee Oxidizer/Acid Test.


Demonstration - step 2

Identifying an Unknown Substance Using HazCat

Hydrochloric Acid

The chart directs the user to the Oxidizer Test (directions for the test are in the field manual).

1. Scoop a small amount of the unknown substance onto a watch dish.

2. Acidify an Oxidizer Test Paper with 3 or 4 drops of Acid Test (3N hydrochloric acid).

Oxidizer test

3. Touch the unknown with the paper.

4. A blue/black or purple color indicates an oxidizer.

 

Demonstration - step 3

Identifying an Unknown Substance Using HazCat

Unknown solid test

The unknown solid substance has tested positive as an oxidizer. The solids chart indicates that the pH Test should be performed next. (The identification path has gone from "Unknown Solid - appears inert" to "Oxidizer Test" with a positive result to "pH Test".)

haz-cat

1. Add 1/4-inch of the unknown to a test tube containing 1/2 inch of water.

pH test

2. Dip the pH Test paper into the unknown solution.

pH strips

3. Compare the colors with those on the pH Test paper container.

The pH appears to be about 11.

4. Return to the solid chart for the next step.

 

Demonstration - step 4

Identifying an Unknown Substance Using HazCat


The pH Test showed that the substance had a pH of approximately 11 which leads to the Oxidizer in Air Test. Here's how it is performed. (The identification path has gone from "Unknown Solid - appears inert" to "Oxidizer Test" with a positive result to "pH Test" - pH 2-14 result to the "Oxidizer in Air Test".)

Haz-Cat Chart
Acid HCL

 

To perform the Oxidizer in Air Test:

1. Acidify an Oxidizer Test Paper with 2 or 3 drops of Acid Test.  

2. Place a pea-size amount of solid, or a dime-sized pool of solution on a watch dish.

3. Acidify the unknown by adding several drops of Acid Test. Look for effervescence.

Oxidizer test

4. Hold the acidified oxidizer paper about 1/2-inch above the effervescing unknown.

5. A color change in the oxidizer paper indicates the escape of chlorine gas from the unknown, which indicates hypochlorite.

 

Demonstration - step 5

Identifying an Unknown Substance Using HazCat

Haz-Cat test

 

A positive result from the Oxidizer in Air Test leads to the Char Hairpin Test. Since the result of the Oxidizer in Air Test indicated that the unknown substance was a hypochlorite, the Char Hairpin Test might seem unnecessary, but as you'll see later on, it is very important. (The identification path has gone from "Unknown Solid - appears inert" to "Oxidizer Test" with a positive result to "pH Test" - pH 2-14 result to the "Oxidizer in Air Test" with a positive result to the "Char Hairpin Test".)

 


How to do the Char Hair Pin Test:

Char hair pin test

1. Place a grain-size amount of solid (this test is usually used to determine explosives) on a watch glass dish.

2. Heat the hairpin until cherry red.

Char hair pin test

3. Touch the hairpin to the unknown.

Note that there is no reaction.

The Char Hairpin Test is used here to differentiate between chlorocyanurates and hypochlorites. Chlorocyanurates resemble hypochlorites (and are used in the same applications), but chlorocyanurate will burn readily on the hairpin, while hypochlorite will have not reaction. The two substances will react violently if mixed, so it is very important to be able to tell the difference here. The unknown substance can now be identified as a hypochlorite.

 

 

 

Demonstration - step 6

Identifying an Unknown Substance Using HazCat


Continuing with the Char Hair Pin Test...

Char hair pin test

 

4. If no reaction occurs on the watch dish, place the hairpin back into the torch flame and look for a reaction.

Sodium, lithium and calcium hypochlorites are all used as chlorinating agents for swimming pools. At first glance hypochlorites may appear to be identical. Calcium hypochlorite is the most common of the three and can be positively identified by a short-lived, brick-red flame color during the Char Hairpin Test, although the color may not always be visible. Sodium hypochlorite is more soluble than calcium hypochlorite and will burn on the hairpin with a yellow flame. Lithium hypochlorite will burn with a long-lasting, bright red flame. The color and duration of this particular flame color would indicate calcium hypochlorite. The identification path has gone from "Unknown Solid - appears inert" to "Oxidizer Test" with a positive result to "pH Test" result of pH 2-14, to the "Oxidizer in Air Test" with a positive result to the "Char Hairpin Test" which showed that the substance was a hypochlorite. Four simple tests in six steps are used in the HazCat scheme to identify calcium hypochlorite.
 
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