1 May 2005
ISA Certified Control Systems Technician (CCST) Program
These questions are from the Level I study guide, Domain 2, Loop Checking.
Level l represents a professional who has a 5-year total of education, training, and/or experience.
1. A process is _______________ if heat is produced by a reaction.
2. A process is _______________ if heat input is required to produce a reaction.
These two questions are asking about chemical reactions that are part of a process. An endothermic reaction is one that absorbs heat from its surroundings. An exothermic reaction occurs with the evolution of heat that transfers into the surroundings.
An example of an endothermic reaction is the decomposition of liquid water into hydrogen and oxygen gas.
H2O (l) + heat → H2 (g) + ½O2 (g)
This intuitively makes sense too, as one must add heat to make steam (g) from water (l).
A typical exothermic reaction is gasoline burning. Upon ignition, it burns spontaneously in oxygen to give CO2 and H2O.
2 C8H18 (gaseous octane) + 25 O2 (g) → 16 CO2 (g) + 18 H2 O (g) + heat
The answer to question one is D; the answer to question two is A .
Nicholas Sheble (firstname.lastname@example.org) explains the answers to CCST questions. For information about the CCST program, go to www.isa.org/ccst.