chemistry rate of reaction

Question

is the rate of disappearance of reactant the same as the rate of appearance of product??? why??

Answer 1

In the reaction of A -> B then the question as you phrased it is accurate. But lets say we are talking about the formation of a diatomic molecule such 2O -> O₂ then suddenly you must rephrase your question. Now the rate of product formation (O₂) is half of the rate of reactant "disappearance" as you phrased it (I would go with reactant consumption rate). You could equally say that atomic oxygen (O) is being consumed at twice the rate that molecular oxygen (O₂). The exact relation will be relative to coefficients of the balanced equations, meaning if three things mix to make something, it will be three times and not twice the reaction rate, etc.

 

In Chemistry, the rate of a reaction is written in the standard rate equation

 

A + B -> C

r = k[A]^x[B]^y

 

the top equation is just the reaction, says A and B make product C

the bottom equation is a differential equation that related the concentration of A and B. k is the reaction constant, a reaction-specific constant, and x and y are experimentally derived exponents that are often mistakenly replaced by the coefficient (which leads to an incorrect solution to the equation and wrong reaction rate). 

 

 

Answer 2

Yes.  Conservation of mass is a fundamental conservation law in Science for most processes.  

 

Energy is always conserved when Mass-Energy equivalence is taken into account.  Mass, however, is not always conserved since it can be transformed to energy.  The only time that mass is not conserved is during "nuclear reactions."  

 

There are many types of nuclear reactions (Fission, Fusion, Alpha, Beta, etc) where mass is not conserved.  In these cases, Energy is still conserved, but mass changes according to the well known (E=mc²)

 

Simple rate-of-reaction chemical reactions preserve mass.  No nuclear processes exist.

Answer 3

I sure hope so.