Chemistry - Rates Of Reaction 👨🦲 Flashcards
Rate of Reaction
The speed at which a reaction takes place
How do you measure the rate of reaction
• measure how quickly the reactants are used up
• measure how quickly the products are formed
Methods to measure rate of reaction
• change in mass
• volume of gas formed
• formation of a precipitate
What 5 subjects affect the rate of reaction
Temperature, Surface area, Catalysts , Concentration, Pressure
What is necessary conditions need to happen for a reaction to take place?
(2 things )
For chemical bonds to be broken the particles need to collide with
- sufficient energy(often known as activation energy)
- The molecules need to collide in the correct orientation /directiom
What is collision theory?
The theory that chemical reactions can occur ONLY when reacting particles COLLIDE with each other and with suffient energy
What is activation energy?
Activation energy is the minimum amount of energy that particles must have to react. Only reactants with energy equal to or greater than , this value will react.
What is a catalyst?
-Substance that speeds up a reaction
- Is not used up by the reaction
- Lowers activation energy by providing an alternate lower enwrgy pathway
Term given for bubblibg or fizzing
Effervescence
How does pressure increase the rate of reaction?
(Pressure can only be used in experiements involving gases)
gases can be compressed unlike solids/liquids .
So if the pressure is increased there are more reactant particles for a given volume, more collisions, rate of reaction is higher.
What does it mean when the gradient is steep in a graph?
The steeper the gradient in a graph, the faster the reaction
Difference between EXothermic reaction and ENdothermic reaction?
Exothermic reaction transfers energy to the surroundings which is why the temperature of the surroundings increase. As the name suggests , energy EXITS. Endothermic reactions take in energy from the surroundings and as the name suggests, energy enters.
How can you spot the difference between an exothermic and an endothermic graph
Exothermic- The product at the end (after it bypasses the activation energy) would have less energy than the reactant started with
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Endothermic-there is more energy in the product than the reactants started with.
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How to calculate the rate of mean reaction
Total volume of gas collected divided by total time taken to collect gas.
Or another definition quantity of reactant used divided by time taken.
How can you keep the temperature of a reaction mixture constant
•Use a water bath
•Use a greater volume of acid
•Use more acid
Describe the relationship between the mass of carbon dioxide given off in one minute and the concentration of acid
The higher the concentration of the acid, the more carbon dioxide will be given off in one minute. The relation is directly proportional.
Why does concentration increase the rate of reaction
Collisions are more frequent between the two reactants and there will be more collisions in the same volume and a given time.
Two features of (whatever type of) chips that need to be the same to make an experiment fair if you are not testing on different types of chips, but rather testing temperature or concentration
The mass needs to be the same, and it needs to have the same surface area.
What is the rate of reaction?
The speed at which a reaction takes place.
How can the rate of reaction be measured?
By measuring how quickly the reactants are used up or how quickly the products are formed.
What is the first method to measure the rate of reaction?
Change in mass.
How does the change in mass method work?
The mass of the flask and contents decreases as the gas formed leaves the flask.
What is the second method to measure the rate of reaction?
Volume of gas formed.
How is the volume of gas formed measured?
A gas syringe is used to connect to the gas produced during the reaction.
What is the third method to measure the rate of reaction?
Formation of a precipitate.
What indicates the formation of a precipitate?
The solution turns milky/cloudy as the precipitate (insoluble solid) is produced.
What is Collision Theory?
For a reaction to happen, the reacting particles must successfully collide.
What is a successful collision?
A collision that leads to a reaction happening.
What is activation energy?
The minimum energy reacting particles must have when they collide for the reaction to take place.
What factors can change the rate of a reaction?
- Temperature
- Concentration
- Surface area
- Catalyst
How does temperature affect the rate of reaction?
Increasing temperature makes particles move faster, increasing the chance of successful collisions.
What happens to particles at a higher temperature?
Particles have more kinetic energy and move faster.
How does concentration affect the rate of reaction?
Increasing concentration increases the number of reacting particles.
What effect does breaking a solid into smaller pieces have?
It increases the surface area.
Why is a larger surface area beneficial in reactions?
It provides more space for reacting particles to collide, increasing the chance of successful collisions.
What is a catalyst?
A substance that speeds up a reaction without being used up.
How does a catalyst affect activation energy?
It lowers the activation energy of the reaction.
What is the purpose of rate graphs?
To follow the course of reaction and compare the rates of similar reactions.
What factors contribute to a faster reaction?
- Higher temperature
- Higher concentration
- Larger surface area
- With catalyst
What factors contribute to a slower reaction?
- Lower temperature
- Lower concentration
- Smaller surface area
- Without catalyst
What is the rate of a reaction?
How quickly reactants are used up or products are produced
What is the equation for calculating the mean rate of reaction?
Mean rate = change in quantity of product or reactant / time taken
What is the unit for rate of reaction in a reaction involving a change in mass?
g/s
What is the unit for rate of reaction in a reaction involving a change in volume?
cm³/s
What is the activation energy?
The minimum amount of energy colliding particles have to have before a reaction will take place
What effect does increasing concentration have on the rate of reaction?
Increases
Why does increasing concentration have this effect?
More reactant particles in the same volume lead to more frequent collisions
What effect does increasing pressure have on the rate of reaction?
Increases
Why does increasing pressure have this effect?
Less space between particles means more frequent collisions
What effect does increasing surface area have on the rate of reaction?
Increases
Why does increasing surface area have this effect?
More reactant particles are exposed and able to collide, leading to more frequent collisions
What effect does increasing temperature have on the rate of reaction?
Increases
Why does increasing temperature have this effect?
Particles move faster, leading to more frequent collisions - particles have the same activation energy, so more collisions result in a reaction
What is a catalyst?
A substance that increases the rate of a reaction but is not used up in the reaction
How do catalysts increase the rate of a reaction?
Lower the activation energy of the reaction, so more collisions result in a reaction
What is the first step in the reaction of marble chips with hydrochloric acid?
Measure out the HCL
What should be done after pouring hydrochloric acid into a conical flask?
Measure out the marble chips
What is the purpose of adding a bung and delivery tube to the flask?
To collect the gas produced in the reaction
How often should gas volume be measured during the reaction?
Every 10 seconds
What is the formula to calculate the mean reaction rate?
Mean rate = total volume of gas produced / time taken
What does a steep tangent on a reaction rate graph indicate?
A faster rate of reaction
What does it mean when the line on a graph goes flat?
The reaction has finished
Fill in the blank: The quicker the mass lost, the ______ the reaction.
quicker
Mystery reward
All of your decisions in life have led you to see this card. Breathe and rest for 10 seconds.
Mystery reward
Free slot to rest for 10.7892 seconds.
Calculate the mean rate of reaction from the given data: At 30s, 20cm³; at 60s, 75cm³.
1.8 cm³/s
What is the significance of adding a tangent to the graph?
To see how the reaction rate changes
What happens to the volume of gas produced as time increases in a quick reaction?
It increases rapidly
What type of graph would show a slow reaction?
A graph with a gentle slope
What does the steepness of the tangent on a graph represent?
The rate of reaction
What does the rate of reaction graph show?
The rate of reaction goes quickly to start with and then starts to level off.
What is the formula to calculate the rate of reaction?
rate of reaction = quantity of product formed / time taken
Calculate the rate of reaction if 650g of product is formed in 50 seconds.
Mean rate = 13g/s
How does increasing the surface area of a solid reactant affect the rate of reaction?
The reaction occurs quicker due to more surface area for reactants to react.
What happens when a reaction is in equilibrium?
The rate of the forward reaction is equal to the rate of the reverse reaction.
Why does increasing surface area lead to a quicker reaction?
There is more surface area for the reactants to react with.
What is the definition of a catalyst?
A catalyst speeds up the rate of a reaction without being used up.
How do catalysts work?
They lower the activation energy and provide a surface area for reactants to bind.
What happens to particles when they are heated?
Particles have more kinetic energy, collide more frequently, and have more successful collisions.
Why does an increase in concentration lead to an increased rate of reaction?
There are more particles in the same volume, leading to more frequent collisions.
