What is the difference between zero order and first order

A few substances are eliminated by zero - order elimination kinetics , because their elimination process is saturated. List of drugs following zero-order kinetics Phenytoin, Phenylbutazone. Theophylline, Tolbutamide.

A first - order process is one whose dynamics can be represented by a first - order differential equation, i. First of all, the only factor which affects the dynamic, or time-based, behaviour of the response is the time constant,.

The larger the value of the time constant the slower the response. Remember the exp notation means the natural constant e raised to the power of whatever follows. Alcohol elimination was originally believed to be a zero - order process, meaning that alcohol was removed from the body at a constant rate, independent of the concentration of alcohol.

Because of this concentration dependence, it is not possible to estimate one single rate of alcohol metabolism. The simplest kind of second - order reaction is one whose rate is proportional to the square of the concentration of one reactant.

A second kind of second - order reaction has a reaction rate that is proportional to the product of the concentrations of two reactants.

Rate of elimination is constant and does not depend on or vary with the drug intake or plasma concentration of the drug. Phenytoin, Phenylbutazone.

For a 2 nd order reaction , the half - life can be expressed based on the integrated rate law. In the case of a second order reaction , the half - life increases with decreasing initial concentration. The law of mass action describes that the speed of a chemical reaction is proportional to the mass of reactants.

According to chemical kinetics, reactions can be categorized as zero order reactions, first order reactions, and second order reaction. The main difference between first order and zero order kinetics is that the rate of first order kinetics depends on the concentration of one reactant whereas the rate of zero order kinetics does not depend on the concentration of reactants.

First order kinetics refers to chemical reactions whose rate of reaction depends on the molar concentration of one reactant.

The rate of the reaction is proportional to the concentration of one reactant. There can be many other reactants taking part in the chemical reaction, but only one reactant will determine the rate of the reaction. Therefore, the other reactants are known to be in zero order with respect to this particular reaction. This is a unimolecular reaction. That means, this reaction is composed of only one reactant. The rate of the reaction can be given as below. Then the rate of the reaction can be given as below.

Here, the value would always be one. That indicates the decomposition of N 2 O 5 g is a first order reaction. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. In case of sale of your personal information, you may opt out by using the link Do not sell my personal information. Cookies Policy. Close Privacy Overview This website uses cookies to improve your experience while you navigate through the website.

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These cookies do not store any personal information. First-order reaction graphs Post by Elizabeth Bamishaye 2I » Thu Mar 08, pm The main difference is the y-axis for both, which is [A] for zero order and ln[A] for the first order. First-order reaction graphs Post by William Satyadi 2A » Thu Mar 08, pm A zero order reaction graph is linear and has a negative slope when the y-axis is the concentration of the reactant, and a first order reaction graph is linear and has negative slope when the y-axis is ln [Reactant].

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