2016年6月17日 · See explanation. The half-life of a chemical reaction, regardless of its order, is simply the time needed for half of an initial concentration of a reactant to be consumed by the reaction. Now, a first-order reaction is characterized by the fact that the rate of the reaction depends linearly on the concentration of one reactant. For a first-order reaction "A " -> " …

2017年1月28日 · t_"1/2"^((2)) = "85.25 s" Notice how you're given the half-life (for one temperature), a second temperature, and the activation energy. The key to doing this problem is recognizing that: the half-life for a first-order reaction is related to its rate constant. the rate constant changes at different temperatures. Go here for a derivation of the half-life of a first …

2018年7月19日 · Well, let us begin from the rate law... Is the FIRST-order half-life dependent on concentration? The first-order rate law for the reaction A -> B is r(t) = k[A] = -(d[A])/(dt) where: r(t) is the rate as a function of time, which we take to be the initial rate in "M/s" k is the rate constant. What are the units? You should know this. [A] is the concentration of a reactant A in "M". …

2016年7月12日 · The half-life, #t_"1/2"#, of a first-order reaction is independent of the initial concentration of the reactant, which is why the problem doesn't provide you with one. In fact, all you need to know in order to calculate the half-life of a first-order reaction is the rate constant, #k#, which in your case is equal to . #k = 7.80 * 10^(-4)"s"^(-1)#

2016年12月13日 · Of course. As rate constants depend on temperature, so does the first-order half-life. For a first-order process, let us consider simply a reactant A, whose rate law is: r(t) = k[A] = -(d[A])/(dt) where [A] is the concentration of A, and -(d[A])/(dt) is the rate of disappearance of A as time passes. To determine the change in concentration over time, we consider an interval …

2017年6月22日 · For some reactions and decay processes, the time for 1 half-life can be in very small fractions of time while some are very large time intervals and expressed in powers of 10. Examples*: => for the isotope Nitrogen-10 (N-10), the half-life can be as small as #2xx10^-22sec.# This could be expressed as #2xx10^-12# picoseconds (ps). Both are the ...

2018年6月24日 · Well, first-order half-lives are constants with respect to reactant concentration... t_(1//2) = (ln2)/(k) where k is the first-order rate constant in "s"^(-1)... So, presumably, you mean, a regular concentration vs. time graph on which the half-life is marked... Apparently, this reactant has a half-life of "100 s". How much time passes until one reaches the second half-life from …

2017年6月16日 · It depends on the order of the reaction with respect to the reactant undergoing half-life decay. The common half-life expressions for one reactant A are: t_"1/2" = ([A]_0)/(2k) (zero order) t_"1/2" = (ln2)/k (first order) t_"1/2" = 1/(k[A]_0) (second order) t_"1/2" = 3/(2k[A]_0^2) (third order) where [A]_0 is the initial concentration in "M" and k is the rate constant in the …

2017年2月5日 · How do you derive first order half life? Chemistry Nuclear Chemistry Nuclear Half-Life. 1 Answer

2015年12月19日 · Simply put, the time needed for #50%# of a reaction to be completed will represent that reaction's half-life. In your case, you know that your first-order reaction is #50%# completed after #30# minutes. This means that after #30# minutes, you will have . #A = 1/2 * A_0 -># half of the initial concentration remains after one half-life. Plug this ...