Around Christmas day of 2022, a mass of very cold air settled in the deep south/southeastern United States (where I live). It remained below freezing for over 24 hours. That is very unusual down here. There was a spate of burst pipes all over the area. Why? Water is one of a very few compounds that expands when it freezes…by approximately 9%!! If a volume of water is sealed off in a section of piping, and that water freezes, it is likely the pipe will rupture. Then, when it warms up again and thaws, liquid water will leave the pipe for an adventure!!
Water expands when it freezes because the water molecules form a six sided crystalline structure in its solid form (remember those six sided snowflakes we all cut out in grade school?). These large crystals cannot nestle together as closely as individual water molecules. So frozen water needs more elbow room, so to speak. The other way to state this phenomenon is that ice is less dense than water. Which is a really good thing for all the fish that live in ponds where it gets cold enough to freeze! The layer of ice on top of a pond insulates the water beneath it from colder air temperatures. If that ice sunk to the bottom of the pond instead, the water on top would freeze then sink and eventually the entire pond could freeze and kill the fish in it.
This made me start to think about all the other ways that water is unlike other liquids… and there are quite a few. They all stem from the fact that water has something called hydrogen bonds or polar bonds between its molecules. You all know that water has 2 hydrogen atoms and 1 oxygen atom: H2O. What most folks don’t know is that each hydrogen atom has one electron to donate to a bond and oxygen needs two electrons to fill its orbital shell. This configuration gives a slightly negative charge to the oxygen end of the molecule, and a slightly positive charge to the hydrogen ends. These charges act like little magnets and opposites attract!
These bonds give water properties that other compounds of similar molecular weight do not have…. Such as
Relatively High Boiling point – Water has a molecular weight of 18 (O=16 , H=1). Ammonia (NH3) has a molecular weight of 17 (N=14, H=1). All other things being equal, they should have similar properties. But I’ve already told you that all other things aren’t equal, haven’t I?? Those hydrogen bonds require more energy to pull them away from one another. That means a higher boiling temperature. Ammonia boils at -28.01°F and water boils at 212°F. Quite the difference.
High Surface Tension – surface tension is defined as “the property of the surface of a liquid that allows it to resist an external force.” Once again, due to the hydrogen bonds, water has the second highest surface tension of any liquid (only elemental Mercury has a higher value). This can be seen in water sheeting off of eaves during a heavy rain, or, back to our fish pond again, water striders doing their thing!
Highest Specific Heat Capacity of Any Liquid- This means it takes a lot of energy to raise the temperature of a given volume water and it also means water can dissipate that heat throughout the entire volume easily. The best visual I’ve seen to explain this is placing a paper cup full of water into a campfire. As long as water is present, the paper won’t burn. Here’s a link to a video (you should really watch this!): https://www.youtube.com/watch?v=fpjLcLa7rkU
This capability is also why water is used in industrial sites for absorbing or transferring heat…there’s literally no better liquid for it. This ability to absorb heat without changing temperature is why the oceans don’t get as hot or as cold as the land… water takes a long time to heat or cool
Lastly, the volumetric ratio of steam to liquid water is higher than most other liquids….1700:1. In other words, if I had a 1ft x 1ft x 1ft cube of liquid water (1 cubic foot) that I turned it into steam and kept at atmospheric pressure, that steam would take up 1700 cubic feet of space. Comparing to ammonia, that ratio is 850.
In the same way that frozen water can rupture pipes, water vaporizing to steam can have devastating effects on systems that aren’t designed for it. If you need an investigation of a loss involving water, in any of its forms, please call our experienced engineering experts at Warren.
As President of The Warren Group, Jennifer Morningstar, B.S.Ch.E, P.E., CFEI, has over 20 years of engineering experience. A licensed professional engineer in several states and a NAFI Certified Fire and Explosion Investigator, she holds a Bachelor of Science Degree in Chemical Engineering from Virginia Polytechnic Institute and State University, as well as a Master of Business Administration from the University of South Carolina. Throughout her engineering career, Jennifer has conducted forensic investigations involving chemical release/exposure, OSHA process safety management, industrial accident investigation, equipment failures, fires & explosions, and scope of damage/cost to repair. Jennifer is a member of the National Association of Fire Investigators (NAFI), the South Carolina chapter of the International Association of Arson Investigators (SCIAAI), and the American Institute of Chemical Engineers (AIChE).
Distillation is a method of separating mixtures of compounds with differing boiling points. Uncle Bill with his still on the hill separates ethanol, that boils at 173°F, from water that boils at 212°F. If the mixture is heated to above 173°F, but below 212°F, the ethanol will boil, the vapor will travel up out of the unit and then can be condensed and served over ice with an olive… Any mixture of two or more chemicals with different boiling points can be separated in this way. The distillation Read More
LIVE WEBINAR: “Property Claims Issues at Manufacturing Facilities” | Presented by WARREN’s President and Senior Consulting Engineer, Jennifer Morningstar, P.E., CFEI.
COURSE LEARNING OBJECTIVES
The learning objectives of this course are to provide the attendees with information on the four major facets of property claims that are commonplace in manufacturing facilities.
Subrogation against third parties;
Boiler & machinery vs property claims;
Scope of loss, and
Each facet will be explored and exemplified by at least one case study.
The Safety Hierarchy states that hazards should be mitigated first by engineering controls, secondly by guarding, and lastly by warning/training. When the first two, engineering controls and guards, fail in a manufacturing setting, a chemical release could occur. A forensic chemical engineer can help determine the root cause of that failure. Read More
Now that you know what ammonia is (see Part One here), how it behaves, and how to safely store it and work with it, let’s look at some areas in industry where it is used.
Anhydrous ammonia has a use in pollution control. Industrial boilers and power plants burn coal or natural gas to make steam and/or electricity. When the fuel is burned using air as the oxygen source nitrogen gets exposed to the heat as well because air is 79% nitrogen. The nitrogen gets oxidized and forms several compounds referred to as NOx (NO, NO2, NO3). NOx compounds are harmful to Read More
Ammonia is a compound consisting of one nitrogen atom and three hydrogen atoms and is denoted by the formula NH3. Its boiling point is -28°F at atmospheric pressure, so unless it is under pressure, it is gaseous at room temperatures. Therefore, pure ammonia is typically stored under pressure in a liquid form. Household ammonia is only 5-10% NH3, the remaining 90-95% is water. Ammonia is extremely soluble in water. It is often depicted like this: Read More