Discover Chemistry

Picture this: a glass of cold water with ice cubes bobbing on top. It feels normal, almost boring — but scientifically, it’s one of the strangest quirks in all of chemistry. Most solids sink in their liquid form. Iron sinks in molten iron. Solid wax sinks in melted wax. So why does solid water — ice — float instead of sinking? The answer lies in a beautiful chemical exception that makes life on Earth possible. The Usual Rule of Chemistry Normally, when a substance freezes, its molecules get packed closer together, making the solid denser than the liquid. That’s why solids usually sink. Density, after all, is just mass per unit volume. If the same amount of material occupies less space, it becomes heavier per unit of volume and sinks. But water breaks this rule. When it freezes, it actually expands, becoming less dense than liquid water. That’s why ice floats, defying the expectation we’d set from almost every other substance. The Hydrogen Bond Trick The secret is in water’s molecular s...

Almost everyone has faced this: you’re peacefully preparing dinner, knife in hand, when suddenly your eyes start to sting and tears roll down your cheeks. It feels almost personal — as if the onion is fighting back. But the truth is far stranger, and much more fascinating: it’s chemistry at work. The Onion’s Defense System Onions don’t “want” to be eaten. Like many plants, they’ve evolved clever chemical defenses. When you slice into an onion, you’re not just cutting through layers of cells — you’re breaking tiny storage sacs filled with special compounds. This is the onion’s natural alarm system, designed to deter animals (and maybe even you) from munching on it too quickly. Meet the Tear Gas Molecule The real culprit is a molecule with a dramatic name: syn-Propanethial-S-oxide. Here’s how it forms. Inside the onion, a harmless substance called sulfoxide sits quietly in the cells. When you chop the onion, an enzyme called alliinase is released. This enzyme reacts with the sulfoxides, ...

Oxygen is one of Earth's most abundant and crucial elements, with profound impacts on chemistry, biology, and the environment. This article delves into various aspects of oxygen, from its discovery and properties to its role in human health and the environment. Discovery and History Oxygen was discovered independently by Carl Wilhelm Scheele in Sweden and Joseph Priestley in England, both in 1774. Priestley isolated oxygen by heating mercuric oxide, while Scheele produced it by heating several compounds, including potassium nitrate. Antoine Lavoisier, a French chemist, later named the element "oxygen" in 1777, from the Greek words "oxys" (acid) and "genes" (producer). 1. Triplet Oxygen    - Molecular oxygen (O2) is commonly depicted with a double bond, but in reality, it has two unpaired electrons, making it a diradical. This makes it slightly paramagnetic, meaning it is weakly attracted to magnetic fields. 2. Oxygen's Discovery    - Oxygen was dis...

Understanding the physicochemical properties of drugs is essential for several reasons, each influencing how drugs are absorbed, distributed, metabolized, and eliminated by the body, ultimately affecting their effectiveness and safety. Firstly, these properties play a crucial role in the absorption of drugs. For instance, drugs that are highly soluble in water are generally absorbed more readily through the gastrointestinal tract into the bloodstream. Conversely, drugs that are highly lipophilic can cross cell membranes more easily and may distribute more readily into fatty tissues, including the brain. Secondly, the distribution of drugs throughout the body is influenced by their physicochemical properties. Lipophilic drugs tend to accumulate in fatty tissues, while drugs that are more hydrophilic may remain primarily in the bloodstream or extracellular fluid. This distribution can impact both the efficacy and potential side effects of a drug. Metabolism and elimination are also affec...

This article will help you to test basic knowledge of physical chemistry. We have provides 54 multiple choice questions with  Solve 54 MCQ'S PHYSICAL chemistry for B.Sc. first year students    1. Gaseous state has A. Definite shape and definite volume B. No definite shape and no definite volume C. Definite shape but no definite volume D. No definite shape but definite volume 2. Which of the following is not an assumption of the kinetic molecular theory of gas? A. Attractive forces of the gas molecules are sufficiently strong B. Molecules of the gas have constant and random motion C. Volume of gaseous molecules are negligible D. average kinetic energy of gas molecules is directly proportional to the absolute temperature of the gas 3. In case of an ideal gas compressibility factor is A. One B. Two C. Three D. Zero 4. van der Waal’s equation is for A. ideal gas B. real gas C. perfect gas D. compressed gas 5. The critical temperature of the water is 647 K, which means A. The ...