A student says, "The initial concentration of a reactant was doubled, and the rate doubled. Therefore the reaction is second order in that reactant." Why might the student say that? What is wrong with the statement? What is the actual order with respect to the reactant?

Answer is in the explanation.

Explanation:

The statement:  "The initial concentration of a reactant was doubled, and the rate doubled" implies the initial concentration is directly proportional to rate of reaction. That is:

Rate = K [A]₀

But this law is rate law of first order reaction. Second order reaction has as law:

Rate = K [A]₀²

These law implies:  "The initial concentration of a reactant was doubled, and the rate quadruplicate", a different statement.

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !