How Reactivity is Predicted

Once you have听added two or more substances to My365bet娱乐, you can see reactivityThe tendency of a substance to undergo chemical change. The reactivity of most substances depends on the temperature and pressure of the surroundings, and on the chemicals with which it comes in contact. Under ordinary conditions, innately reactive substances are those that react rapidly with water, air, and other common components of the environment, as well as substances that self-react (decompose or polymerize). predictions about what might happen if any of those substances were to mix together.

To make those predictions, CAMEO 365bet娱乐 first identifies each chemical's reactive groups, and then predicts the kind of pair-wise reactions likely to occur when members of these groups are mixed together. (Each chemical in the database has been assigned to one or more reactive groupsReactive groups are categories of chemicals that typically react in similar ways because they are similar in their chemical structure. For purposes of predicting reactivity between mixed chemicals, each substance in CAMEO 365bet娱乐 has been assigned to one or more reactive groups, based on the known chemistry of that substance.听based on its chemistry.)

To help understand pair-wise reactions and how reactive groups are involved, it may be useful to look at an example of how CAMEO 365bet娱乐 predicts chlorine and gasoline will react if they are mixed.how CAMEO 365bet娱乐 predicts chlorine and gasoline will react if they are mixed.

Remember: Pair-wise reactions are based on the reactive group pairings, not the chemicals themselves.

Gasoline has been assigned to a single reactive group (Hydrocarbons, Aliphatic Saturated), while chlorine has been assigned to two reactive groups (Oxidizing Agents, Strong and Halogenating Agents). How do I see reactive group assignments?

To make the predictions for a mixture of gasoline and chlorine, CAMEO 365bet娱乐 looks at these reactive group pairings:

  • [Hydrocarbons, Aliphatic Saturated] + [Oxidizing Agents, Strong]
  • [Hydrocarbons, Aliphatic Saturated] + [Halogenating Agents]
Note: If a chemical has more than one reactive group assignment, those reactive groups aren't mixed together. In this example, for instance, chlorine's two assigned reactive groups鈥擮xidizing Agents, Strong and Halogenating Agents鈥攚ould not be mixed together.

The reactivity predictions that you see in the Compatibility Chart are actually a summary of all the predictions for each reactive group pairing assigned to the two selected chemicals. The chart includes short summary statements about the hazards; click on the intersecting cell to jump to a section below that chart that includes more detailed statements and potential gas byproducts. Additionally, in that section, you can also click on the Documentation link to read background information on why CAMEO 365bet娱乐 made a particular reactivity prediction for that pair-wise combination.

Reactivity predictions for gasoline and chlorine.

Reactions Between More than Two 365bet娱乐

When you have more than two substances in your My365bet娱乐 Collection, you should be aware that CAMEO 365bet娱乐 can only account for the reactions between two substances at a time.

For example, if you added acetone to the example mixture above, CAMEO 365bet娱乐 would look at the reactivity of individual pairs (acetone + chlorine; acetone + gasoline; and chlorine + gasoline) rather than the combination of all three together (acetone + chlorine + gasoline). If fact, the pair-wise calculations are even more complicated than that, because they are based on the reactive groups assignments as described in the example above rather than the chemicals themselves.

Important Note: When there are three or more substances in the mix, they may react together in ways that CAMEO 365bet娱乐' pair-wise reactions can't predict. Learn more about reactivity prediction limitationsLearn more about reactivity prediction limitations

  • For example, glycerin and nitric acidA substance that donates hydrogen ions that can be accepted by a base. Acids have a pH below 7. react very little when they're mixed together. However, if sulfuric acid is added to the mix, the three chemicals react together to produce the powerful explosiveA material synthesized or mixed deliberately to allow the very rapid release of chemical energy (that is, an explosion). Also, a chemical substance that is intrinsically unstable and liable to detonate under conditions that might reasonably be encountered. nitroglycerin. CAMEO 365bet娱乐 doesn't predict this reactionThe change that takes place when two or more substances interact to form new substances., because it looks at the pairs (glycerin + nitric acid; glycerin + sulfuric acid; and nitric acid + sulfuric acid) rather than all three chemicals together.
  • In other cases, one of the chemicals may act as a catalystA substance that speeds up (catalyzes) a chemical reaction between other substances without itself being chemically changed or consumed. Catalysts are widely used in the chemical industry. For example, an iron/aluminum catalyst is used to synthesize ammonia and a platinum catalyst is used to manufacture nitric acid. that accelerates the rate of reaction between other chemicals in the mixture. For example, nickel carbonyl catalyzes many polymerizationChemical reaction in which small molecules join to form larger molecules; polymerization reactions typically release heat, and can cause containers to overpressurize. reactions and other kinds of synthetic organicGenerally, compounds that contain the element carbon, except for some carbon-containing compounds that are considered to be inorganic (carbon oxides, carbides, carbon disulfide, phosgene, the cyanides of the metals, and carbonyl sulfide). reactions. In such cases, the reactivityThe tendency of a substance to undergo chemical change. The reactivity of most substances depends on the temperature and pressure of the surroundings, and on the chemicals with which it comes in contact. Under ordinary conditions, innately reactive substances are those that react rapidly with water, air, and other common components of the environment, as well as substances that self-react (decompose or polymerize). hazard may be greater than predicted.

However, reactions among more than two chemicals are relatively uncommon in nature, except for the catalyzed reactions that are common components of the metabolic processes of living organisms.

Compatibility Color-Coding on Reactivity听Predictions

Reactivity predictions are shown in the Compatibility Chart, and the intersecting cell for a pair of chemicals is marked as Incompatible (On the Compatibility Chart, a red square icon indicates incompatible.), Caution (On the Compatibility Chart, a yellow square icon indicates caution.), or Compatible (On the Compatibility Chart, a green square icon indicates compatible.). (The cells also contain short phrases that summarize the reactive hazard predictions, such as "Corrosive" or "Generates heat"; a cell without any short hazard phrases means that there is no known hazardous reaction for that pair.) Below is a summary of the critical decision points that went into making the compatibility color-coding assignments for the reactivity predictions.

The compatibility decisions are all made within the context of a specific scenario: two chemicals (in approximately equal proportions) mixing thoroughly under ambient conditions for a warm climate (i.e., one atmosphere of pressure and temperatures of 75-120掳F [24-49掳C]) and with no catalytic impurities.听A note about intentional and unintentional chemistryA note about intentional and unintentional chemistry

Intentional Chemistry

The discussion above about chemical compatibility hazards and color-coding in CAMEO 365bet娱乐 is based on a specific scenario. For intentional chemistry, most reactions are driven forward by heat, pressure, catalysis, etc. and do not follow the coding we are applying here. However, the appropriate application of process safety engineering can mitigate the known hazards of reaction. This includes the whole palette of engineering design, including duplicate systems for power, cooling, mixing, pressure relief, etc.

Unintentional Chemistry

The compatibility hazard codes and colors only apply to a specific scenario. In an uncontrolled accident, mixing conditions may be changing very dramatically and rapidly. Although the Compatibility Chart and predicted hazards may apply to a situation one moment, they may not apply the next moment (depending on conditions). For instance, a train derailment may initially create a "compatible" mixture (from the standpoint of the Compatibility Chart). If, after a short period of time, a fire starts near enough to the spilled chemicals to begin driving a hazardous reaction in the formerly compatible mixture, this new situation would not be predicted by CAMEO 365bet娱乐. In these cases the use of CAMEO 365bet娱乐 is inadequate for predictive purposes, and appropriate chemical advisory assistance should be sought. Expert chemists from the companies that produced the spilled chemicals may be the most appropriate source of information in such cases.

The chemical reactions between two materials are considered to be

  • On the Compatibility Chart, a red square icon indicates incompatible.听Incompatible (hazardous) if they meet any of the following criteriaIncompatible (hazardous) if they meet any of the following criteria
    • The reaction produces a large amount of heat (above approximately 100 calories/gram), which may lead to a hazardous situation. The interaction between strong acidsA substance that donates hydrogen ions that can be accepted by a base. Acids have a pH below 7.听and strong basesA substance that accepts hydrogen ions donated by an acid. Bases have a pH greater than 7.听will exceed this threshold. Another example is the thermal runaway reactions associated with uncontrolled polymerizationChemical reaction in which small molecules join to form larger molecules; polymerization reactions typically release heat, and can cause containers to overpressurize.鈥攖he most often cited example of hazardous heat release. Polymerization reactions are complicated by the intrinsic instability of the monomersOne of the molecules that link together to make a polymer. For example, the monomer of natural rubber is isoprene. Monomers may be naturally occurring or synthetic.听involved in the reaction, and the very rapid buildup of heat can overwhelm any process safety features that have been implemented.
    • Hazardous products are formed in the reaction (such as unstable, corrosiveLiquid or solid that can destroy human skin or lung tissue or corrode metals., flammableEasy to ignite and burns readily., or toxicPoisonous; can injure or kill people or other organisms. products) or gases are produced. One of the greatest causes of accidents in the past has been inadequate process safety design that didn't take gaseous product generation into account, leading to pressure buildup in containers.
  • On the Compatibility Chart, a yellow square icon indicates caution.听Caution (possibly hazardous) if they meet any of the following criteriaCaution (possibly hazardous) if they meet any of the following criteria
    • The intrinsic instability of reactants may lead to unforeseen hazardous situations. For example, when polymerizableCan react with itself. Polymerization reactions typically generate heat and could cause container to overpressurize, which can lead to a fire or explosion. materials are mixed with chemicals that are not known to be incompatible, a hazardous reaction could still occur due to an unexpected interaction (such as inhibitorSubstance added to a polymerizable substance to slow down or prevent a polymerization reaction. The inhibitor level in a substance can drop over time, making a reaction possible. deactivation).
    • One of the chemicals in the pair commonly contains impurities that are incompatible with the other chemical in the pair. An example of this is the slow formation of peroxides in ethers that have been exposed to air. In some cases, the peroxide impurities may react hazardously with the other chemical in the mixture, even if that chemical would not react with pure ethers.
    • A hazardous reaction could occur between the two chemicals, but it is slow under the conditions of the mixing scenario.

    Whenever a yellow cautionary warning appears, click on the documentation link for that pair (in the detailed pair-wise predictions below the Compatibility Chart) to understand the nature of the hazard and whether it applies to your scenario.

  • On the Compatibility Chart, a green square icon indicates compatible.听Compatible (unlikely to be hazardous) if they meet all of the following criteriaCompatible (unlikely to be hazardous) if they meet all of the following criteria
    • The materials either do not react with one another or react so slowly as to be considered non-hazardous under the conditions of the mixing scenario.
    • If the mixture does react, only a small amount of heat is released by the reaction (less than approximately 100 calories/gram).
    • The chemical mixture does not produce unstable, flammableEasy to ignite and burns readily., corrosiveLiquid or solid that can destroy human skin or lung tissue or corrode metals., or toxicPoisonous; can injure or kill people or other organisms. products.