Chapter 6/7 Flashcards
What is the rate of chemical reaction?
Give an example of slow reaction and moderate speed reaction, fast reaction
How fast the reactants are changed into products
Slow- chemical weathering = acid rain damage to limestone buildings
Moderate- magnesium reacting with an acid to create gentle stream of bubbles
Fast- burning
Speed of reaction?
Amount of product formed or reactant used / time
What does a steep line on a graph show about rate of reaction?
And why does line becomes flat eventually?
faster rate of reaction
Quick reaction
over line becomes flat as reactants are used up
What is the collision theory?
Frequency of collisions of reacting particles (how often collide)
More Collisions there are faster the reaction as more energy is transferred
Particles have to collide with enough energy for a successful collision
Minimum amount energy needed for reaction to take place?
Activation energy - this much energy breaks the bonds in the reactants and starts the reaction
What does increasing temperature do to the rate?
Increases the rate
Particles move faster = collide more frequently
So have more energy so enough to make reaction happen
Increasing concentration OR pressure? RATE OF REAXTION
Increases the rate
If a solition is more concern then more particles reacting in the same volume
Increases pressure as same number of particles in a smaller space
= collisions between reacting particles more frequent
Increasing surface area? Rate
Increases the rate
Increasing surface are to volume ratio = particles around it will have more area to work on
= collisions more frequent
Using a catalyst ? Rate
Increases rate
Catalyst substance that speeds up a reaction without being used up - not part of equation
Decrease activation energy and provide ALTERNATIVE REACTION PATHWAY with lower activation energy
How to find the mean rate of whole reaction?
y value / total time taken
Or change in y/ change in x
How to use tangent to find the reaction rate at particular point?
Work out the gradient of a tangent Eg rate of reaction at 3 mins 1. Position ruler at 3 mins 2. Draw tangent and extent the line 3. pick two points gradient = change in y/ change in x
what happens to reactant as they react?
concerntrations fall so forward reaction will slow down
What happens to products in a reaction?
more and more products are made they’re concerntrations rise and backward reaction will speed up
what is it called when the forward reaction will be exactly same rate as backward?
Equilibrium
when is equilibrium reached?
if reversible reaction take place in a close system as nothing can escape
what does it mean if equilibrium is on the right?
the concentration of products is greater than reactants
What does it mean if equilibrium on the left?
Concerntrations of reactants is greater than products
EXAMPLE
ammonium chloride - ammnia + hydrogen chloride
Equilibrium on the right as more product
The position of equilibrium depends on the …?
Temp
Pressure
Concerntation of reactants and products
In a reversible reaction if the reaction is endothermic in one direction what will it be in the other?
Exothermic
thermal decomposition example
Energy transferred from the surrounding by endothermic reaction is equal to the energy transferred to the surrounding - exothermic
hydrated copper sulfate= anhydrous copper sulfate+ water
If heat hydrated crystals drives water off and leaves white powder = endothermic
if add couple of drops of water to powder = get blue crystals back again= exothermic
what is le chateliers principle
idea If change the conditions of a reversible reaction at equilibrium the system will do the opposite
what happens if you decrease temp at equilibrium?
products of equal decrease for an endo reaction
And increase for exothermic
