The Rate And Extent Of Chemical Change Flashcards
State the 3 ways rate of reaction can be found?
●Measuring amount of reactants used
●Measuring amount of products formed
●Measuring the time it takes for a reaction mixture to become opaque or change colour
Explain how you find the rate of reaction when measuring amount of reactants used?
●If one product is a gas, measure the mass (g) of the reaction mixture before and after the reaction happens and the time it takes
●The mass of the mixture will decrease
●Put into equation
●Units for reaction rate = g/s
When measuring the amount of reactants used what is the unit for the reaction rate?
g/s grams per second
Explain how you calculate the rate of reaction when measuring the amount of products formed?
●If one of the products is a gas, measure the total volume of gas produced in cubic centimetres (cm^3) with a gas syringe and the time it takes
●Put into equation
●Units for rate of reaction are cm^3 / s
What are the units for the rate of reaction when measuring the amount of products formed ?
Cm^3 / s.
Cm^3 per second
Describe how you find the rate of reaction when measuring the time it takes for a reaction mixture to become opaque or change colour?
●Time how long it takes for mixture to change colour
●Rate of reaction= 1÷ time taken for solution to change colour
What is the equation to find mean rate of reaction?
Mean rate of reaction =
Amount of reactant used or product formed ÷ Time
What is needed for a chemical reaction to occur?
Chemical reactions only occur when REACTING PARTICLES COLLIDE WITH EACH OTHER WITH SUFFICIENT ENERGY
What is the minimum amount of energy needed to cause a reaction called?
Activation energy
What are the four factors that affect the rate of reaction?
♡Temperature
♡Concentration
♡Surface area
♡Catalysts
How does temperature affect chemical reactions/collision theory?
•In a hot reaction mixture particles move more quickly, collide more often with greater energy, more successful collisions
How does concentration affect reaction rate / collision theory?
●At higher concentrations the particles are crowded closer together, collide more often, more successful
How does increasing pressure affect reaction rate?
Increasing pressure of reacting gases also increases amount of collisions
How does surface area affect rate of reaction/collision theory?
○Small pieces of a solid reactant have a larger surface area in relation to their volume
○More particles are exposed and available for collisions, so there are more collisions resulting in a faster reaction
How do catalysts affect the rate of reaction/collision theory?
■Catalysts reduce the amount of energy needed for a successful collision, make more collisions successful, speed up a reaction, provides a surface area for molecules to attach to which increases their chances of bumping into each other
■Allow reaction to happen via a path of lower activation energy
Why do we plot reaction rates?
Graphs can be plotted to SHOW PROGRESS OF A CHEMICAL REACTION
On a reaction rate graph what does a steep line mean?
Steeper the line = FASTER THE REACTION
What does it mean if the reaction rate graph line is horizontal?
When one of THE REACTANTS IS USED UP, the reaction stops = line becomes horizontal
3 key things to remember when plotting or reading a reaction rate graph?
●Steeper the line = faster the reaction
●When one of the reactants us used up, reaction stops = line becomes horizontal
●Same amount of product is formed from the same amount of products, regardless of rate
Why is increasing rate of chemical reactions important in industry?
Reduces cost in industry
