Rates Of Reaction Flashcards
What is the equation for the rate of reaction?
1/ Average time
Average time = Time 1 + Time 2 / 2
Rate = Change in a measured quantity / time taken
Explain collision theory?
For a reaction to take place between reacting particles it must:
- Have a successful collision
- Have enough energy to react
What is activation energy?
The minimum amount of energy needed to for a chemical reaction to occur.
How does increasing the surface area affect the rate of reaction?
- More particles are exposed to the other reactants
- Meaning there are more successful collisions in a given time period
- Increases the rate of reaction
Diagram for measuring the rate of reaction
Look in book!
What are the properties of carbon dioxide?
- odourless gas
- Colourless gas
- Heavier than air
- When cooled to -78 degrees it sublimes into dry ice
- It does not support combustion
- It is slightly soluble in water giving an acidic solution
Explain the combustion of carbon when there are different supplies of oxygen?
Complete combustion - Plentiful supply
Carbon + Oxygen = Carbon dioxide
Incomplete combustion - Limited supply
Carbon + Oxygen = Carbon Monoxide
Properties of carbon monoxide?
- Toxic
- Colourless
- Odourless gas
What are some uses of carbon dioxide?
- Fire extinguishers - does not aid combustion
- Carbonated drinks - soluble in water and dissolved under high pressure
- Dry ice via sublimation
Diagram for the preparation of carbon dioxide?
Look in book :]
How does temperature effect the rate of reaction?
At the temp increases, the particles gain energy and move faster, leading to more successful collisions in a given period of time.
The rate of reaction increases
What is a catalyst?
A catalyst is a substance that can increase the rate of a reaction.
The catalyst itself remains unchanged at the end of the reaction it catalyses.
How does a catalyst increase the rate of reaction?
As it provides an alternative pathway with a lower activation energy
Example of a catalyst?
Hydrogen peroxide will decompose to form water and oxygen:
Hydrogen peroxide –> water + oxygen
The reaction is extremely slow but can be speeded up using a catalyst called MANGANESE(IV) OXIDE.
What is the test for oxygen?
Relights a glowing splint
What are the properties of oxygen?
- Colourless, odourless gas
- Slightly soluble in water
- It is neutral
- It is very reactive. Will react with many substances to form the oxides
What are uses of oxygen?
- Medicine
- welding
- Rocket Engines
What are the observations of the reaction of oxygen with Magnesium?
Grey magnesium burns with a bright white flame producing a white ash of magnesium oxide. The solid is a basic oxide.
What are the observations of the reaction of oxygen with Cooper
Red-brown solid glows red when heated and a blue-green flame is produced. A black layer of basic copper oxide is formed.
What are the observations of the reaction of oxygen with Iron
Grey solid burns with orange sparks. A black basic oxide is formed.
What are the observations of the reaction of oxygen with Sulphur
Yellow solid melts to form a viscous brown liquid. This burns with a blue flame to produce the pungent smelling acidic sulfur dioxide gas.
What are the observations of the reaction of oxygen with Carbon
Carbon monoxide produced in a limited supply
Carbon dioxide produced in a plentiful supply
Black carbon burns with orange sparks producing an acidic colourless gas
What are the properties of Hydrogen?
- Colourless, Odourless Gas
- Insoluble in Water
- Less dense than air
- Neutral
What is the test for Hydrogen?
Squeaky pop when a lit splint is put in a test tube
Uses of hydrogen and their reasons?
Meteorological Balloons - less dense than air
Hardening Oils - can convert unsaturated vegetable oils into solid at room temperature
Potential Clean Fuels - reacts with oxygen only producing water
What are the observations of the reaction of Hydrogen with Oxygen
Hydrogen + Oxygen –> Water
Oxygen is reduced as it gains hydrogen.
Hydrogen is the reducing agent as it has caused the reduction to take place.
What are the observations of the reaction of Hydrogen with Copper Oxide
Hydrogen acts as the reducing agent and reduces copper oxide to copper.
Copper oxide + Hydrogen –> Copper + Water
What are the observations of the reaction of Hydrogen with Nitrogen
Nitrogen is a very unreactive element and will react with very few other elements.
It will however react with hydrogen to produce ammonia in a process known as the Haber Process.
Nitrogen + Hydrogen Ammonia
How does concentration increase the rate of reaction?
The higher the concentration the higher the rate of reaction as there are more acid particles to successfully collide with in a given period of time.
How do you prepare carbon dioxide for use?
Look for diagram in first book (5/12/24)
