How to calculate chemical reaction half life 10

The decay law of the nucleus is: n=no*(1 2) (t t) where: no refers to the number of nuclei at the initial moment (t=0) t is the decay time, t is the half-life, and n is the number of nuclei left after decay.

The half-lives of radioactive elements vary widely, from much less than a second to tens of billions of years.

The half-life is calculated as m=m(1 2) (t t).

where m is the mass of the nucleus before the reaction, m is the mass of the nucleus after the reaction, t is the reaction time, and t is the half-life. In physics, the shorter the half-life, the more unstable the atom is, and the higher the chance of decay of each atom. Since the decay of an atom occurs naturally, i.e., it is impossible to predict when it will occur, it is expressed in terms of chance rate.

Einstein's Law:

When atoms begin to decay, their number decreases and the rate of decay slows down. For example, an atom has a half-life of one hour, and after one hour its undecayed atom will be left in two-quarters, two hours later it will be one-quarter, and after three hours it will be one-eighth.

The decay of an atom produces another element and emits alpha, beta particles, or neutrinos, which, after decay, also emits gamma rays. According to Einstein's formula for conservation of mass and energy e=mc2;Decay is one of the ways in which mass is converted into energy.

Usually the products produced by decay are also radioactive, so there will be a series of decay processes until the atom decays to a stable isotope.

The first-order reaction half-life t = ln2 k, where k is the reaction rate constant. Secondary reaction half-life t = 1 [k(a0)].

In physics, especially high school physics, half-life does not refer to a small number of atoms, it is defined as the time it takes for half of the nuclei of radioactive elements to decay. Decay is the behavior of atomic nuclei in the microscopic world, and one of the characteristics of the microscopic law is that "a single microscopic event cannot be ****".

That is, for a particular atom, we only know the probability of it decaying, but we don't know when it will decay. However. Quantum theory can make statistics about the behavior of a large number of atomic nuclei**. The half-life of radioactive elements describes such a statistical law.

Related information

In a statistical sense, the half-life refers to a period of time t, during which there is a 50% probability that an atom of an unstable isotope of an element will decay. "50% probability" is a statistical concept that only makes sense for a large number of repetitive events. When the number of atoms is "huge", 50% of the atoms will decay in time t.

Quantitatively, "half of the atoms" decay. In the next t time, another 50% of the remaining undecayed atoms will decay, and so on. But when the number of atoms is no longer "huge", for example, when only 20 atoms remain undecayed, then the "50% probability" is no longer meaningful, and the number of atoms that decay after time t is not necessarily 10 (20 50%).

The average time interval required for an atom to decay by half is called the half-life.

Half-life of a chemical reaction Half-life is an ideal way to describe the speed at which a chemical reaction proceeds.

In the equation, c0 is the initial concentration, and c is the concentration at time t. It can be seen that the half-life of the first-order anti-sullen response is inversely proportional to the rate constant k1 of the reaction, and has nothing to do with the initial concentration of the reactants, for a given reaction, t1 or t2 is a constant, which is a characteristic of the first-order anti-sufficiency response, according to which it can be judged whether a reaction is a first-order reaction. But in the secondary reaction, the half-life is different from the primary reaction.