10 most difficult chem­istry riddles

Water gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas. Synthesis gas is a useful product, but requires careful handling due to its flammability and the risk of carbon monoxide poisoning. The water-gas shift reaction can be used to reduce the carbon monoxide while producing additional hydrogen, resulting in water gas.

Aspartame produces 4 kilocalories of energy per gram when metabolized, sucrose (table sugar) produces 3.9 kilocalories. However, aspartame is approximately 200 times sweeter than sucrose, so it is consumed in much smaller doses.

Cranberry glass or 'Gold Ruby' glass is a red glass made by adding gold salts or colloidal gold to molten glass. The glass is typically hand blown or molded. Legend holds that cranberry glass was first discovered when a noble tossed a gold coin into a mixture of molten glass

Pure water is about 7 at 25 °C; this value decreases with increasing temperatures. At 50 °C, it is 6.55. It is also worth to note, that water that has been exposed to air is mildly acidic, because it absorbs carbon dioxide from the air.

Iron is most abundant in the Earth's outer and inner core, and it is the fourth most common element in the Earth's crust.

White Sands, having 442 total square kilometers of dune fields, is the world's largest surface deposit of gypsum. Unlike other desert sands, it is cool to the touch, due to the high rate of evaporation of surface moisture and the fact that the sands reflect, rather than absorb, the sun's rays.

The green tint found in most tempered glass is a result of iron used in the production of glass sheets, where it is added as an ingredient to act as a lubricant. In fact, except in manufacturing processes designed to minimize iron use to avoid the green tint, you’ll find that green cast in all sheets of glass–not just tempered glass

Pepsi Cola, first introduced in 1898, was named after pepsin (enzyme) and kola (nuts). In 1931, the company entered bankruptcy and changed hands. The new owners changed the recipe to resemble more Coca-Cola.

Methanol has a much weaker sedative effect than ethanol, which leads the victim to drink more than it would normally do with ethanol. Methanol is oxidized to formaldehyde and then to the poisonous formic acid in the liver.

Argon makes up 0.934% of the earth's atmosphere. It is more than twice as abundant as water vapor and 23 times as abundant as carbon dioxide.