Table of Contents
Position of Hydrogen in the Periodic Table
Hydrogen is positioned at the top of the periodic table because it is the lightest element. It is positioned to the left of helium because it has one less proton in its nucleus.
Occurrence of Hydrogen
Hydrogen is the lightest and most abundant element in the universe. It is a colorless, odorless, and tasteless gas. Hydrogen gas is used in many applications such as welding, lasers, and cryogenics. It is also an important component of rocket fuel.
Discovery of Hydrogen
In 1766, Henry Cavendish was the first person to discover hydrogen. He was able to do this by mixing water with sulfuric acid. This created a gas that was able to be ignited.
Isotopes of Hydrogen
Isotopes are atoms of the same element that have different numbers of neutrons. Hydrogen has three isotopes: hydrogen-1, hydrogen-2, and hydrogen-3.
Hydrogen-1 is the most common isotope and has one proton and no neutrons. Hydrogen-2 is also called deuterium and has one proton and one neutron. Hydrogen-3 is also called tritium and has one proton and two neutrons.
The different isotopes of an element have different physical properties. For example, hydrogen-2 is used in heavy water, which is used in nuclear reactors.
Preparation of Dihydrogen
To a mixture of 1.0 M potassium hydroxide and 1.0 M hydrogen gas in a 2.0 L flask is added a solution of 0.5 mol of ethylene glycol in 1.0 L of water. The system is then heated to reflux.
The following reaction occurs:
2 KOH (aq) + H2 (g) → 2 K+(aq) + 2 OH-(aq)
2 H2O (l) → 2 H2 (g) + O2 (g)
The hydrogen gas is collected over water at room temperature and a pressure of 1 atm.
The yield of hydrogen gas is 1.35 mol.
Properties of Dihydrogen
Dihydrogen is a colorless, odorless gas. It is the lightest and most abundant element in the universe. Dihydrogen is non-toxic and does not cause any adverse health effects.
Chemical Properties of Dihydrogen are Listed Below
:
• Dihydrogen is a colorless, odorless gas.
• It is non-toxic and non-flammable.
• It is a good solvent and is miscible with most other gases.
• It is a good reducing agent and is used in the manufacture of ammonia and other chemicals.
Uses of Dihydrogen
Monoxide
Dihydrogen monoxide is used as a cooling agent in many industrial processes. It is also used in the production of plastics, resins, and other synthetic materials. Dihydrogen monoxide is also used as a solvent in many chemical processes.
Hydrogen Peroxide
Hydrogen peroxide has a number of medical and household uses. It is a natural bleach and can be used to clean surfaces and whiten teeth. It is also an effective disinfectant and can be used to kill bacteria and viruses. In the home, hydrogen peroxide can be used to remove blood stains and to disinfect cuts and scrapes.
Chemical Properties
CAS Number: 107-06-2
Appearance: colorless to light yellow liquid
Odor: characteristic
pH: 2.5-3.5
Boiling Point: 153-154°C
Flash Point: 44°C
Specific Gravity: 1.02-1.04
Vapor Density: 3.4
Water Solubility: soluble
Aromatic Content: none
Carcinogenicity: none
Mutagenicity: none
Toxicity: none
LD50: n/a
Notes:
Chloroform is a volatile, colorless liquid with a characteristic odor. It is soluble in water and has a boiling point of 153-154°C. Chloroform is a carcinogen and a mutagen. It is also toxic.
Uses of Hydrogen Peroxide
One of the most popular uses of hydrogen peroxide is as a disinfectant. It can be used to disinfect surfaces and to kill bacteria and viruses. It can also be used to clean wounds and to help prevent infection.
Structure of Water
Water has a three-dimensional tetrahedral molecular structure, with the oxygen atom at the center and four hydrogen atoms at the corners. This structure is due to the electron-pair geometry of the oxygen atom and the valence electron-pair repulsion theory.
Hard and Soft Water
There is a lot of confusion about the terms “hard” and “soft” water. Many people think that if their water is “hard,” it is bad for their skin and hair, and if their water is “soft,” it is good for their skin and hair. This is not always the case.
“Hard” water is water that has a high mineral content, while “soft” water has a low mineral content. Neither water type is inherently better or worse for your skin and hair. It all depends on your individual needs.
If you have hard water, it is important to use a water softener to reduce the mineral content. This is because hard water can cause a build-up of soap scum and minerals on your skin and hair, which can lead to a variety of skin and hair problems.
If you have soft water, it is important to use a water softener to prevent the water from leaching minerals from your hair and skin. This is because soft water can strip your skin and hair of its natural oils and minerals, leading to dryness and hair loss.
Type of Hardness of Water
The hardness of water is a measure of the concentration of calcium and magnesium ions in the water. The higher the concentration of these ions, the harder the water.
Heavy Water
Heavy water is a form of water that contains a higher than normal concentration of deuterium, a hydrogen isotope.
Comparison between Properties of Water and Heavy Water
The following table provides a comparison of some physical properties of water and heavy water.
Property Water Heavy water
Molecular weight 18.01 g/mol 20.01 g/mol
Molar volume 18.02 cm3/mol 20.02 cm3/mol
Density 1.00 g/cm3 1.10 g/cm3
Boiling point 100°C 101.4°C
Latent heat of vaporization 2.26 kJ/mol 2.33 kJ/mol
Heat capacity 4.184 J/g·K 4.601 J/g·K
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