The rate and extent of chemical change Flashcards
State five factors affecting the rate of a chemical reaction ?
- Concentration of reactants
- pressure of gases (volume)
-Surface area
-Temperature
-catalysts
What is the collision theory ?
Chemical reactions can occur only when reacting particles collide with each other with sufficient energy {more than or equal to activation energy}
Describe and explain the effect of increasing temperature on the rate of reaction
When the temperature increase there is a faster reaction
Describe and explain the effect of increasing concentration on the rate of reaction?
Conc. increases = faster reaction
more reactants = more frequent collisions
Describe and explain the effect of increasing pressure of a gas on the rate of reaction
Increasing the pressure of reacting gasses , is the same as increasing concentration .
It increases the number of gas molecules in the same volume and so increases the frequency of Collisonss and therefore increases the rate of reaction
Volume and pressure are inversely proportional
Describe and explain the effect of increasing surface area
If solid reactants are in smaller pieces , they have a greater surface area. Increasing the rate of reaction ,
block of magnesium reacts slower with acid then magnesium powder
What is a catalyst and how does it work ? How does it affect the reaction profile ?
A catalyst changes the rate of reaction but is not used up. It increases rate of reaction by providing a different pathway for the reaction that has a lower activation energy. The reaction profile for a catalysed reaction will have a lower maximum of the curve(lower activation energy )
What is an enzyme ?
An enzyme is a molecule that acts as a catalyst in a biological system.
what is a reversible reaction ?
A reversible reaction occurs when the products of a reaction can react backwards to produce the original reactants.
When is dynamic equilibrium reached ?
In a closed system, when the forward and reverse reactions occur at the same rate and the concentrations of reactants and products remain
Describe Le chatelier’s Principle
If a system is at equilibrium and a change is made to and of the conditions , then the system responds to counteract change and restore the equilibrium.
Describe the effect of changing the concentration of reactant and product on the postion of the equilibrium
If concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again
Describe the effect of a catalyst on the position of the equilibrium
no effect
it just speeds up both forward and backward reactions equally
- equilibrium is achieved
