lessonsloha.blogg.se - Hydrogen peroxide uses

HYDROGEN PEROXIDE USES SERIES

HYDROGEN PEROXIDE USES SERIES

It has the highest (theoretical) boiling point of this series (X = O, S, N, P). Hydrogen peroxide has several structural analogues with H mX−XH n bonding arrangements (water also shown for comparison).

Density of aqueous solution of H 2O 2 H 2O 2 ( w/w).

Dotted lines separate solid–liquid phases from solid–solid phases. Phase diagram of H 2O 2 and water: Area above blue line is liquid. This boiling point is 14 ☌ greater than that of pure water and 36.2 ☌ less than that of pure hydrogen peroxide. The boiling point of the same mixtures is also depressed in relation with the mean of both boiling points (125.1 ☌). Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression down as low as -56 ☌ pure water has a freezing point of 0 ☌ and pure hydrogen peroxide of -0.43 ☌. In aqueous solutions, hydrogen peroxide differs from the pure substance due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Crystals of H 2O 2 are tetragonal with the space group D 4Ĥ or P4 12 12. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state. The molecular structures of gaseous and crystalline H 2O 2 are significantly different. It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of ribonucleic acids and therefore an origin of homochirality in an RNA world.

It is the smallest and simplest molecule to exhibit enantiomerism. The approximately 100° dihedral angle between the two O–H bonds makes the molecule chiral.

For comparison, the rotational barrier for ethane is 1040 cm −1 (12.4 kJ/mol). These barriers are proposed to be due to repulsion between the lone pairs of the adjacent oxygen atoms and dipolar effects between the two O–H bonds. Although the O−O bond is a single bond, the molecule has a relatively high rotational barrier of 386 cm −1 (4.62 kJ/ mol) for rotation between enantiomers via the trans configuration, and 2460 cm −1 (29.4 kJ/mol) via the cis configuration. Hydrogen peroxide ( H 2O 2) is a nonplanar molecule with (twisted) C 2 symmetry this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy. Structure and dimensions of H 2O 2 in the solid (crystalline) phase