Monday, 22 May 2017

Hazards in chemical process industries - Chemical hazard

Chemical hazard

What are hazards?

 Situations that poses a threat or causes harm to people, the environment, or property.

 What is Industrial hazard? -

Any condition produced by industries that may case injury or death to personnel or loss of property. Hazards may be dormant, armed or active.


 Prioritisation of hazards involves making visible all risks in an operation, the probability of occurrence and the potential damage.

 Then, what is Chemical Hazard: 

     This is a type of occupational hazard caused by exposure to chemicals in the workplace. It is any chemical that can cause illness, injury, or an emergency.

 It can be divided into; Physical and health risk Chemical hazard may be: Toxic, corrosive, irritant, carcinogenic, mutagens, flammable etc.
Physical and health hazard

Many chemical may cause severe burns, if they come in contact with living tissue. Routes to exposure ingestion inhalation from fumes poisoning explosion

    Duration of Exposure of chemicals

Acute - Short Minutes to hours.
Sub acute - Longer up to 90 days
Chronic - Prolonged /Repeated over days, months & years.
    The effect of the chemicals is independent on duration of exposure, but dependent on concentration and type of chemicals exposed.

Safety measures

1) Wear all required PP Es (professional protective equipment) such as: hand gloves, helmets, eye goggles, safety boots and so on, depending if you will be working with a solid, liquid or gaseous form of hazardous chemicals.

2) Identify the hazardous characteristics of a chemicals using a safety data sheet or a pictogram to know how best to handle them.


 Hazardous-waste management is the treatment and disposal of waste that has the ability of causing harm and damage to people, property or environment if it is left untreated or wrong fully disposed.

Characteristics of untreated hazardous waste.

  • Reactivity 
  • Radioactivity 
  • Ignitable 
  • Corrosive 
  • Infectiousness 
  • Toxicity

Watch this self explanatory video


Wednesday, 17 May 2017

Cohesive and Adhesive forces: Definition, differences and effects.

Cohesive vs adhesive force

Adhesion and cohesion

Someone emailed me and suggested do a piece on this topic. Well, for easy understanding of the concept of cohesion and adhesion force, i wrote this brief post.

Happy Learning!


  The force of attraction between the molecule of the same substance is called cohesion force.
 The force of attraction between the molecules of different substance is called adhesion force.

     Water has both adhesive and cohesive properties. Adhesion of water to glass is stronger than the cohesion of water. hence, when water is spill ed on a clean glass surface it wets the glass.

On the other hand, the cohesion of mercury is greater than the adhesion to glass. Thus, when mercury is spill ed on glass it forms small spherical droplet or larger flattened droplets and does not wet glass.
Mercury forming a small spherical droplet on glass.

Effects of Cohesion

1) Surface tension: This is a property of liquid that gives it an elastic surface, this is as a result of cohesive forces between adjacent molecules. Here, the molecules at the main body of liquid are pulled equally in allowing directions by neighbouring molecules.
       Water because of this property, heavier objects with less force compared to surface tension to float across it.

2) Meniscus: This is the property of liquid that gives it a curved surface. It has both cohesive and adhesive properties.

Meniscus property at the surface forming a concave and convex curve.

     If the cohesive forces between the liquid molecules is greater than its adhesive force, the surface will form a convex curve.
     If the adhesive forces between the liquid molecules is greater than the cohesive forces, the surface will form a concave curve.

  If  both the adhesive and cohesive forces are equal, the surface is horizontal.

3)  Capillary  action: Here, the cohesive and adhesive forces work together to keep the liquid away from it's natural forces of gravity. The cohesive forces causes the water to form droplets and the adhesive forces keeps the drop in place.
Capillary action
Capillary action on leaves.