Intermediate is created and destroyed, and therefore does not appear on the net equation, which is . Thus, the intermediate is . Note that when asked for an intermediate, the coefficient in front of it is not used, rather we are looking for the species that is a product of one reaction and a reactant in a subsequent step.

An increase in temperature leads to an increase in reaction rate for endothermic reactions, while a decrease in temperature will slow down their rate.

For zero order reactions, reaction rate is independent of reactant concentrations; therefore, changing \[A\] and \[B\] will have no effect on reaction rate.

The rate law for this reaction would simply be , where k is the rate constant at a given temperature.

First order reactions have rates that are directly proportional to only 1 reactant. In radioactive decay, the rate of decrease of a radioactive material is proportional only to the amount of the material.

A zero-order reaction has a rate of formation of product that is independent of changes in concentrations of any of the reactants; however, since the rate constant itself is dependent on temperture, changing the temperature can alter the rate.

When the concentration of B doubles, the rate doubles. Making this reaction first order in regards to compound B. When the concentration of A doubles the rate is unaffected, making this reaction zero order in regards to compound A. This leaves a rate law of rate=k\[B\]

The rules for determing the reaction order with respect to inividual reactants are as follows.

If the concentration of a reactant is doubled and the rate of product formation is doubled then the reaction is first order with respect to this individual reactant.

If the concentration of a reactant is doubed and the rate of product formation is quadrupled then the reaction is second order with respect to this indivudal reactant

If the concentration of a reactant is tripled and the rate of product formation increases by nine times then the reaction is third order with respect to this indivudal reactant

If the concentration of a reactant is changed and the rate of product formation is not significantly changed then the reaction is zeroth order with respect to this individual reactant.

These rules also work in reverse.

That is if the concentration of a reactant is halved and the reaction rate decreases by a factor of 2, then the reaction is considered frst order with respect to this individual reactant.

The overall reaction rate is determined by adding the reaction orders of each indivual reactant together. So if the reaction was first order with respect to reactant \[X\] and first order with respect to \[Y\], it is third order overall

So the answer to the question is that the reaction is second order overall becasue the reaction is first order with respect to both reactants X and Y, which gives a second order reaction overall.

The rate based on concentration is related to the coefficients in front of the compounds. Based on the reactants the rate should be negative (because change in concentration for the forward reaction will be negative) and based on the products should be positive. This means that II is incorrect. The rate for each compound in the reaction should be divided by it's coefficient to make it all related to 1M, showing that I and III are correct.

The reactant is not included in the rate law expression, and therefore altering its concentration does not affect the rate of the reaction. Catalysts always increase the rate of reactions by lowering its activation energy. Increasing temperature (average kinetic energy of the molecules) increases the frequency of collisions, and increases the proportion of collisions that have enough energy to overcome the activation energy and undergo a chemical reaction. Increasing the concentration of will increase the rate of the reaction as indicated by the rate law.

For this question, we're asked to identify something that will always increase the rate of a reaction. Notice that the question specifically states "always."

Let's go through each answer choice and see how it affects the reaction rate.

When the concentration of reactants is increased, this may increase the reaction rate, but not always. For example, if a reaction is zero-order with respect to its reactants, then changing the reactant concentration will have no effect on the rate.

Just like with reactants, decreasing the concentration of products may or may not change the reaction rate. If the reaction rate is zero-order with respect to the products, then a change in their concentration will have no effect on the reaction rate.

A change in temperature is the only thing that is guaranteed to change the reaction rate. This is because changing the temperature will directly change the rate constant of the reaction. Increasing the temperature will increase the rate constant, and hence the reaction rate.

The rules for determing the reaction order with respect to individual reactants are as follows.

If the concentration of a reactant is doubled and the rate of product formation is doubled then the reaction is first order with respect to this individual reactant.

If the concentration of a reactant is doubled and the rate of product formation is quadrupled then the reaction is second order with respect to this indivudal reactant

If the concentration of a reactant is tripled and the rate of product formation increases by nine times then the reaction is third order with respect to this individual reactant

If the concentration of a reactant is changed and the rate of product formation is not significantly changed then the reaction is zeroth order with respect to this individual reactant.

These rules also work in reverse.

That is if the concentration of a reactant is halved and the reaction rate decreases by a factor of 2, then the reaction is considered frst order with respect to this individual reactant.

The overall reaction rate is determined by adding the reaction orders of each individual reactant together. So if the reaction was first order with respect to reactant \[X\] and first order with respect to \[Y\], it is third order overall.

So we know that the reaction is second order overall as defined by the question. It is first order with respect to Y because when Y was doubled the reaction rate was doubled so the reaction order is first order with respect to Y. So to ensure that the reaction is second order overall the reaction must be first order with respect to X. As compared to Experiment 1, Experiment 3 has the same concentration of reactant Y but the reaction rate is doubled, this must be due to a change in the concentration of reactant X. So if the \[X\] in experiment 3 is double the \[X\] in experiment 1 the reaction would be first order with respect to X and second order overall.