Tips for CRW Users

Here are some tips to help you use the Chemical Reactivity Worksheet (CRW) more effectively.

1. Be sure to look at the Reactivity information about each substance to find out whether it is air- or water-reactive.
   
   To do this, from the Mixture Worksheet, click "New Search", then type in the substance's name, CAS number, or UN/NA number. Double-click the chemical name that matches your substance of concern. You'll find the "Air and Water Reactions" section on the "Reactivity" tab of the Chemical Datasheet.
   
   

   
   
   

2. Look elsewhere than the Mixture Worksheet to get the full story.

   
   Example: The CRW correctly predicts a number of hazards between lithium aluminum hydride with an ether such as diethylene glycol dimethyl ether (DGD).

   

   But, over time, ethers such as DGD can combine with atmospheric oxygen to form peroxides. These peroxides can combine explosively with lithium aluminum hydride. (Double-click "diethylene glycol dimethyl ether" on the Mixture Worksheet, then click the "Reactivity" tab on the Chemical Datasheet.)

   

   If the ether contains water, the lithium aluminum hydroxide and water can react--in a potentially violent manner--to form hydrogen. (Double-click "lithium aluminum hydroxide" on the Mixture Worksheet, then click the "Reactivity" tab on the Chemical Datasheet.)

   

   The CRW alerts you to both these hazards.
   
   

3. Earlier versions of the CRW did not predict specific reaction gases, but instead reported things like "flammable gas generation" or "liberates toxic gas", which required further checking. Version 2.0 of the CRW now presents potential gaseous products for any given mixture for which gases are predicted, along with literature citations for those gases.

   
   Click "Compatibility Chart" in the lower right of the Reactivity Worksheet. On the chart, click on a cell that represents a combination of chemicals. In the lower left of the window, click the tab, "Potential Gases".
   
   Example: When you combine nitric acid and sodium hydrosulfide, the Compatibility Chart for this combination shows Hydrogen Sulfide and acid fumes as reaction products.

   

   It may be helpful to click the "Potential Gases Documentation" tab to view the literature citations for Hydrogen Sulfide.
   
   

4. Generally, chemicals in the database are hazardous. The "Special Hazard" denotations are for especially acute hazards. Examples of Special Hazards are "Air reactive" and "Peroxidizable."

   
   Example: The Special Hazards section of the Chemical Datasheet for sodium aluminum hydride shows the chemical to be highly flammable, a strong reducing agent, water-reactive, and air-reactive.

   

   But no "Special Hazards" notation doesn't mean no hazards.

5. Materials that pose certain special or acute hazards have been assigned to nine hazard classes as well as to reactivity groups. These hazard classes (with hazard class numbers in parentheses) include:
   • highly flammable (101)
     
   • explosive (102)
     
   • polymerizable (103)
     
   • strong oxidizing agent (104)
     
   • strong reducing agent (105)
     
   • water-reactive (107)
     
   • air-reactive (108)
     
   • peroxidizable (111)
     
   • radioactive (400)

   You can view reactivity information about substances in a particular hazard class by using the CRW's advanced search. On the Worksheet, click "New Search." In the Basic Chemical Search window, click "Show More Search Fields" in the lower left. Under Reactive Hazards, select the hazard of interest from the drop-down list.