# Determine the value and units of the rate constant

## Calculate the value of the rate constant. PLEASE HELP!

determine the rate law of the reaction and find the value of the rate constant (k) with proper units. Next, create a ratio with the rate laws for 2 experiments.

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The rate constant is a proportionality factor in the rate law of chemical kinetics that relates the molar concentration of reactants to reaction rate. It is also known as the reaction rate constant or reaction rate coefficient and is indicated in an equation by the letter k. Here, k is the rate constant and [A] and [B] are the molar concentrations of the reactants A and B. The letters a and b represent the order of the reaction with respect to A and the order of the reaction with respect to b. Their values are determined experimentally.

The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. The rate law for a chemical reaction is an equation that relates the reaction rate with the concentrations or partial pressures of the reactants. In this equation, [A] and [B] express the concentrations of A and B, respectively, in units of moles per liter. The exponents x and y vary for each reaction, and they must be determined experimentally; they are not related to the stoichiometric coefficients of the chemical equation. Lastly, k is known as the rate constant of the reaction.

In studying a chemical reaction, it is important to consider not only the chemical properties of the reactants, but also the conditions under which the reaction occurs, the mechanism by which it takes place, the rate at which it occurs, and the equilibrium toward which it proceeds. According to the law of mass action, the rate of a chemical reaction at a constant temperature depends only on the concentrations of the substances that influence the rate. The substances that influence the rate of reaction are usually one or more of the reactants, but can occasionally include products. Catalysts, which do not appear in the balanced overall chemical equation, can also influence reaction rate. The rate law is experimentally determined and can be used to predict the relationship between the rate of a reaction and the concentrations of reactants.

## 18.8: Rate Law and Specific Rate Constant

How to Find the Rate Constant of a Reaction (Given Table)

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This question is concerned with the method of initial rates which can be used if more than one species is reacting. We need to keep the concentration of one species constant while varying the concentration of the other. We do this by measuring the initial rate of reaction because, at this point, the concentration of each species has not fallen. It has gone from sf 1. Now consider experiments 1 and 3. This has been altered by a factor sf 4. It is, therefore, 2nd order with respect to sf [NO].

If you're seeing this message, it means we're having trouble loading external resources on our website. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Science Chemistry Kinetics Reaction rates and rate laws. Introduction to kinetics. Rate law and reaction order. Finding units of rate constant k. Experimental determination of rate laws.

The rate law in general just relates the rate r t with the rate constant k and the concentration [Y] of reactant Y and [Z] of reactant Z :. We do not know m or n yet, so we must find those to finish writing the rate law. To make our lives easier, let us set [Z] as a constant in the rate law. That way, when [Y] changes, we know it must influence r t. Thus, we focus on experiments 1 and 2 and the change in the initial Y concentration in relation to the change in initial rate:. The rate constant is specific to the reaction , not to the experiment.

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### 1 COMMENTS

1. Tim G. says:

where k is some constant and x is the order of the reaction in respect we change the concentration of NOBr, we can determine the value of x.