# Analysis of the Half-Life of a Substance

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The rate of a reaction would be the change of concentration of a reactant divided by the time (Green & Damji 161). The rate law is an expression deduced to show the relation of rate to the concentrations of the reactants in a chemical reaction. The rate law equals the rate constant, multiplied by the concentration of the reactants raised to their respective reaction orders (Green & Damji 170). The rate law of the equation given above is: k is the rate constant (given in M/sec or sec-1 or M-1sec-1) A is first reactant and [A] is the concentration of the first reactant (given in M) m is the order with respect to A * Any reactant in brackets refers to the concentration of the particular reactant The rate constant is a variable that is defined using a set of characteristics (Green & Damji 170): • It is dependent on temperature and the availability of a catalyst (a substance that increases rate) • It is measurable through experimentation • It is specific to each chemical reaction • It does not change throughout a reaction Reaction order is defined as the relationship between the concentrations of reactants and the rate of the reaction or simply as the power to which the reactants’ concentrations are raised (Green & Damji 170). The power raised is the coefficient to the left of the reactant, as seen in the rate law above. The overall reaction order refers to the sum of all the powers (Green & Damji 170). For example if the reaction order of [A] was 2 and the reaction order of [B] was 1, the reaction order would be a third reaction order. Three reaction orders will be discussed in this exploration: • Zero reaction order (when [A] would be raised to the power of 0) • First reaction order (when [A] would be raised... ... middle of paper ... ... . Green, John, and Sadru Damji. Chemistry International Baccalaurate. Third ed. N.p.: IBID, 2008. Print. "Half-life of Drugs." Howmed.net. N.p., n.d. Web. 9 Mar. 2014. . "Integration." The Free Dictionary. Farlex, n.d. Web. 29 Jan. 2014. . Rouse, Margaret. "Half-life." What Is ? N.p., Jan. 2006. Web. 29 Jan. 2014. . Tobin, Patrick. International Baccalaureate: Mathematic Standard Level. Ed. Fabio Cirrito. Third ed. N.p.: IBID, 2007. Print. "What Are Radioisotopes?" Foro Nuclear. N.p., n.d. Web. 10 Mar. 2014. .