Jotter 2 Flashcards
What is Oxidation?
It is a loss of electrons in reactants in any reaction.
What is Reduction?
It is a gain of electrons in reactants in any reaction.
When in a Redox reaction does Oxidation and Reduction occur?
At the same time.
How do you identify Oxidation and Reduction in a Redox reaction?
Using ion-electron equations.
Where in the data booklet do you find elements and compounds that are strong reducing agents?
Elements and compounds in the top right of the electrochemical series.
Where in the data booklet do you find elements and compounds that are strong oxidising agents?
Elements and compounds in the bottom left of the electrochemical series.
What is an indicator of reduction or oxidation in an element?
It’s electronegativity.
What is the pattern of electronegativity of a reducing agent?
Elements with low electronegativity tend to form ions by losing electrons and are therefore act like reducing agents.
What is the pattern of electronegativity of a oxidising agent?
Elements with high electronegativity tend to form ions by gaining electrons and are therefore act like oxidising agents.
Where in the periodic table are reducing and oxidising agents?
Strongest reducing agents are found in group 1 and the strongest oxidising agents are found in group 7.
What else except elements can be used for oxidation or reduction?
Compounds, group ions and molecules.
What is the gas that used in a blast furnace to reduce iron (III) ions to iron atoms?
Carbon Monoxide.
What are some useful oxidising agents.
Hydrogen Peroxide and Potassium Permanganate.
Potassium Permanganate is a useful oxidising agent, what is its use?
It is very effective against fungal infections such as athletes foot and is also used to prevent disease in fish in ponds.
Hydrogen Peroxide is a useful oxidising agent, what is its use?
Hydrogen Peroxide breaks down coloured compounds meaning it can be used as bleach for clothes and hair.
Where can examples of complex ion-electron equations be found?
In the data booklet and they usually contain hydrogen ions and water.
In what conditions will most of the Redox reactions occur?
In neutral or acidic conditions.
What is one of the things you should make sure happens when balancing a redox equation?
You need to make sure that the same number of atoms is each element is being oxidised or reduced on each side of the half equation.
What should you do in a redox equation if oxygen atoms are present?
Balance them by adding water molecules to the opposite side of the half equation.
What should you do in a redox equation if hydrogen atoms are present?
Balance them by adding hydrogen ions on the other side of the half equation.
What should you make sure both half reactions are in terms of charge?
You have to make sure they have the same overall charge on each side which is achieved by adding electrons.
Why must reactions be controlled in industrial processes?
They must be closely controlled as if the rate is too slow then the reaction will not be economically viable but if it’s too high then an explosion might occur.
What must particles do to have a successful chemical reaction?
They must collide with each other.
When particles collide what are the 2 important factors that must happen?
There must be enough kinetic energy at which these particles collide in order for the reaction to occur (activation energy).
The particles must collide with the correct collision geometry (angle).
In collision theory what does the letter E represent?
The minimum kinetic energy for a reaction to occur.
What happens when the reactant particles collide with the required activation energy (Ea)?
They form an activated complex which is an unstable arrangement of atoms which breaks down to form the products of the reaction.
What happens if particles collide with the correct activation energy but the wrong collision geometry?
The activated complex will not be formed meaning no reaction will occur.
What effect will reducing the particle size have on the rate of reaction in collision theory?
Reducing the particle size will increase the surface area of the reactant as this means that more particles are exposed resulting in a higher chance for successful collision.
What effect will increasing the concentration of the reactants have on the rate of reaction in collision theory?
An increase in concentration of the reactant will overall result in more particle allowing for a higher chance of collision, meaning the rate of reaction is increased.
What effect will increasing the temperature have on the rate of reaction in collision theory?
Raising the temperature will allow the activation energy to be reached o even surpassed and will speed up the rate of reaction as particle will be moving quicker.
What does increasing the temperature increase other than rate of reaction?
Raising the temperature increases the kinetic energy meaning more particles can collide successfully as they will have the right activation energy.
What effect will increasing the pressure have on the rate of reaction in collision theory?
More pressure will result in the particles of the reactant being packed closer together meaning more collisions can occur as there is now a smaller space but the same amount of particles.
What effect will a catalyst have on the rate of reaction in collision theory?
A catalyst will provide the reaction with a different reaction pathway with a lower activation energy meaning more particles will be able to successfully collide.
What needs to be done in order to record the average rate of reaction?
Record the change in mass of the reactants or products in a given time.
OR
Record the change in volume of the reactants or products in a given time.
ESSENTIAL
Change in the concentration of reactants or products.
What else can be done when it is too difficult to measure the change in a chemical reaction (for example colour change)?
The relative rate calculation can be used instead which is a reaction which consists of:
1 over the time taken for the reaction.
AND
1 over the rate over reaction.
What is enthalpy change?
It is the difference between the energy of the reactants and the energy of the products and is represented by a (delta) H
What is the enthalpy change in an exothermic reaction?
Always negative.
What type of chemical reactions are most reactions part of?
Exothermic (meaning they release energy).
What might exothermic reactions in industry require in order to be removed to prevent the temperature from rising to a dangerous level?
Heat.
What 3 groups are alcohols classified in?
Primary, Secondary and Tertiary
Where can the boiling points and melting points of alcohols be found?
In the data booklet (page 10)
What causes the boiling point to increase in alcohols?
An increase in the number of carbon atoms per molecule.
Why do more hydroxyl groups increase the boiling point of alcohols?
Since hydroxyl groups (-OH) are polar this leads to more hydrogen bonding meaning more energy is required to break them.
What is volatility?
Volatility is the ease of evaporation.
Why does volatility decrease?
Volatility decreases as the number of carbon atoms per molecule increases.
What is the process for the preparation of of ethanol called?
Fermentation.
What is used in the preparation of ethanol?
Glucose (C₆H₁₂O₆) and the enzyme Zymase that is found in yeast, this process converts glucose into ethanol and carbon dioxide.
How strong of a solution can fermentation produce?
Fermentation can only produce a solution with a concentration of 15% as anything higher kills the yeast.
What process is required to increase the concentration of an alcohol from 15% to the 40% of a spirit?
Distillation
What is Synthesis Gas (used in industrial preparation of methanol)?
It is a mixture of carbon monoxide and hydrogen.
How is synthesis gas made?
It is made by steam reforming either coal or methane over a nickel catalyst.
What needs to be combined with Synthesis Gas to form Methanol?
Zinc Oxide Catalyst.
What can methanol be converted into and why is it important?
Methanol can be converted into Methanal which is used to make thermosetting plastics.
What is Dehydration?
It is a process which involves the removal of water from a compound.
What product does the Dehydration of alcohol give you?
An Alkene.
What is lost within an alcohol during dehydration?
The hydroxyl group from one carbon and one hydrogen from an adjacent carbon (this forms an alkene).
What else other than Aluminium Oxide can be used as a catalyst during the dehydration of an alcohol?
Concentrated Sulphuric Acid as it is a strong dehydrating agent.
What might happen to larger secondary or tertiary alcohols when they are dehydrated?
They can form a mixture of isomers.
What do alcohols produce when undergoing combustion?
Carbon dioxide and water.
What is Oxidation?
It is when the oxygen to hydrogen ratio increases and is accomplished by removing a H from the Hydroxyl group.
What is complete oxidation also known as?
Combustion.
