Untitled Deck Flashcards
(18 cards)
What is a reaction rate?
Reaction rate is how fast a chemical reaction happens how quickly reactants turn into products.
Why do we study reaction rates?
Control how fast or slow reactions go.
Improve industrial processes (like making medicines or food).
Understand natural and biological reactions (like how enzymes work or how fast pollution breaks down).
What is the initial rate?
The initial rate is how fast the reaction is going right at the start (just after time = 0).
What is the instantaneous rate?
The instantaneous rate is the speed of the reaction at any specific moment during the reaction.
What is the rate law?
The rate law is a formula that shows how the reaction rate depends on the concentration of the reactants.
What is the rate constant (k)?
The rate constant is a number that tells how fast the reaction is at a certain temperature.
How does rate law relate to reaction mechanism:
The rate law helps identify the reaction mechanism by showing how the rate depends on the concentration of reactants. It usually reflects the slowest step in the mechanism, known as the rate-determining step.
What is pseudo-first order reaction with example:
A pseudo-first order reaction looks like a first-order reaction because one reactant is in large excess and its concentration stays nearly constant. An example is the hydrolysis of ethyl acetate in water, where water is in excess.
What is zero, first, and second order reaction with example:
A zero-order reaction has a constant rate independent of reactant concentration, like NH₃ decomposition on a catalyst. A first-order reaction has a rate directly proportional to one reactant’s concentration, like radioactive decay. A second-order reaction depends on the square of one reactant or on two reactants, like 2NO + O₂ → 2NO₂.
Why rate of reaction increases with temperature:
When temperature increases, molecules move faster and collide more often and with more energy, making it easier to overcome activation energy and form products.
What is activation energy:
Activation energy is the minimum amount of energy needed for reactants to successfully collide and start a reaction.
What is collision theory:
Collision theory states that chemical reactions happen when molecules collide with enough energy and the correct orientation to break and form bonds.
What is exponential factor:
The exponential factor, written as e^(-Ea/RT), shows the fraction of molecules that have enough energy to react at a given temperature.
What is pre-exponential factor:
The pre-exponential factor, or frequency factor (A), represents how often reacting molecules collide with the right orientation to possibly react.
Why reaction requires energy:
Reactions require energy to break existing bonds in reactants before new bonds can form in the products. This energy is needed to reach the transition state.
what is catalyst and what it does?
A catalyst alters the rate of reaction without itself being consumed
* A catalyst increases the reaction rate by lowering Ea
Catalysis
how do determine 1st and zero order in catalyst?
if the reactant concentration is higher than catalyst concentration it is zero order but its lower then it is first order.
what is efficient and specify?
Efficient means enzymes speed up reactions massively—often by a factor of 10¹⁰ or more.
Specific means they only act on certain molecules or bonds; for example, trypsin only cuts peptide bonds after lysine or arginine.
