2 H2 + O2 ==> 2 H2O
A Lewis Acid (conjugate) is an electron pair acceptor and a Lewis Base (conjugate) is an electron pair donor.
NH3 + H3O(+) ==> NH4(+) + H2O
Lewis Lewis Lewis Lewis
Base Acid Acid Base
In particular, water and the Hydrated Proton, H3O(+), are a conjugate acid-base pair, as the hydrated proton is able to donate a proton to water and water is able to receive the proton.
H(+) + H2O ==> H3O(+)
Lewis Lewis
Base Acid
Na2O + H2O ==> 2 NaOH
Basic oxides form salts and water on reaction with acids.
Na2O + 2HCl ==> 2 NaCl + H2O
CuO + 2 HNO3 ==> Cu(NO3)2 + H2O
Strongly basic oxides form compounds with water containing a metal combined directly to a hydroxyl group, they are therefore called hydroxides. The hydroxides of sodium and potassium are also called alkalis.
K2O + H2O ==> 2 KOH
Biochemical oxygen demand is therefore used as an empirical measure of the amount of certain biologically degradable waste types of organic pollutant that are present in water.
Biochemical oxygen demand is calculated by keeping a sample of water containing a known amount of oxygen for five days at 20 degC in the dark. The oxygen content is measured again after this time.
A high biochemical oxygen demand indicates the presence of a large number of microorganisms, consuming large amounts of organic matter, which suggests a high level of pollution.
There is an empirical relationship between the two determinants that describe pollution load in a sample (i.e. between biochemical oxygen demand and chemical oxygen demand).
In 1913 AD, Neils Bohr used the particle theory of the electron to explain the spectrum of the hydrogen atom.
Bohr postulated that the hydrogen atom consisted of a central positive nucleus round which an electron moved in atomic orbit and that an electron may only be found in one of a limited number of those orbits.
The number of orbits was limited, each corresponding to a definite energy level, where the angular momentum, mvr, of the electron in its path about the nucleus must always be equal to nh/2( (where n = 1, 2, 3...) Thus,
mvr = nh/2 where m is the mass of the electron v is the velocity r is the radius of the orbit n is an integer called a Quantum Number used to characterising the orbit and h is Plank's constant.Bohr also postulated that as long as an electron remains in a given orbit it neither absorbs nor emits energy, and that movement of an electron from a low energy state to a higher energy state involves absorption of energy, and movement of an electron from a higher energy state to a lower energy state involves emission of energy in the form of radiation.
Thus, the lines in the spectrum of hydrogen are due to electrons falling from the excited state (i.e. a higher energy level) to the ground state (i.e. the lower energy). Each line in the hydrogen spectrum is ascribed to the transfer of an electron from an orbit of a high n value to one of a lower n value.
The Boltzmann constant, k, is as the gas constant per molecule.
k = R / NaNA = 1.380622 * 10^-23 JK-1
Boyle's Law applies to ideal gases only. Real gases deviate considerable form this ideal relationship.
It is called after the Irish physicist and chemist Robert Boyle
A chemical bond between atoms involves the overlap of an atomic orbital from each of the two atoms involved in the bond and keeps the molecule intact as an entity.
For example, in methane the bond energy of the carbon to hydrogen bond is one quarter of the Enthalpy of the synthesis process.
CH4(g) ==> C(g) + 4 H(g)
Bond energies can be calculated from the standard enthalpy of formation of the compound and from the enthalpies of atomisation of the elements. Energies calculated in this way are called average bond energies or bond energy terms. They depend to some extent on the molecule chosen; the C-H bond energy in methane will differ slightly from that in ethane. The bond dissociation energy is a different measurement, being the energy require to break a particular bond.
Carbon, C, can form double bonds and Carbon Dioxide, CO2, is an example of a compound that exist as discrete molecules. However, since silicon cannot form double bonds, Silicon Dioxide, SiO2, (i.e. Silica) only forms an infinite three-dimensional tetrahedral structure.