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Flashcards in C3b Deck (12):
1

What experiments can you do to follow the rate of reactions?

-a rate of reaction that produces gas can be observed by measuring how quickly gas is produced:
*measure the change in mass while the experiment is happening, mass will fall as gas is released, take readings of mass at regular time intervals
*measure volume of gas given off in a gas syringe at regular time intervals

2

What does rates of reactions depend on?

-collision frequency of reacting particles (more collisions, faster reaction)
-energy transferred during collisions (particles have to collide with enough energy for a collision to be successful)

3

How the amount of product determined?

-depends on the amount of reactant started with
-more reactant means more particles, which will have more reactions so more product
-total amount of product is directly proportional to limiting reactant
once all the limiting reactant is used up the reaction can't continue, even if some reactants are in excess

4

How is the rate of reaction increased?

-by more collisions

5

What does the rate of reaction depend on?

-temperature
-concentration
-size of particles
-prensence of catalyst

6

How does concentration (pressure) affects the rate of reaction?

-more concentrated solutions have more particles of a reactant in the same volume)
-making collisions more likely
-increasing pressure in a gas means molecules are more crowded , so frequency of collision increases

7

How does temperature affects the rate of reaction?

-temperature increase means particles move faster, moving quicker means more collisions
-temperature increase, increases the energy in collisions (since particles move faster) meaning more particles will collide with enough energy to make reactions happen

8

How does a catalyst affects the rate of reaction?

-increases number of successful collisions
-gives reacting particles a surface to stick to where they can collide with each other (reducing the energy needed to react before)
-number of collisions isn't increased, but successful collisions are

9

How does the size of particles affects the rate of reaction?

-breaking a solid reactant into smaller solid particles increases surface area
-particles around it have more area to work on, so collision frequency increases

10

What are limiting reactants?

-the reactant being totally used up

11

What are reactants in excess?

-reactants left behind at the end of a reaction

12

Why do factories making fine powders have to be careful?

-fine powders of combustible materials disperse in air and burn incredibly fast because of the big surface area
-if there's a spark they explode (very fast reaction that releases lots of gaseous produces very quickly)