Unit 5 - Chemistry Flashcards
What does neutralisation mean?
A reaction between an acid and a base which produces a neutral solution
What are the products if you do acid + base?
Salt + water
What is the formula for Hydrochloric Acid?
HCl
Formula for Sulphuric Acid?
H₂SO₄
Formula for Nitric Acid?
HNO₃
Formula for Sodium Hydroxide?
NaOH
Formula for Potassium Hydroxide?
KOH
Formula for Calcium Hydroxide?
Ca(OH)₂
What products are made from Potassium hydroxide + Nitric acid (word equation)
Potassium Nitrate + Water
Which ion is present in all acids?
H⁺
Which ion is present in all alkalis?
(OH⁻)
What is the difference between an alkali and a base?
A base is a something that react with an acid to form water and a salt. An alkali is any base that is soluble in water
How many numbers on the pH scale?
14
What are the alkali pH levels?
8-14
What are the acid pH levels?
6-0
What pH level is neutral?
7
What is an ion?
Charged atom or charged group of atoms
What is the generic word equation for reacting a metal and an acid?
Metal + Acid → Salt + Hydrogen
(You can remember it by MASH)
What’s the formula of hydrogen gas?
H₂ (Diatomic molecule)
What is the general word equation for reacting a metal carbonate and an acid?
Metal Carbonate + Acid → Salt + Water + Carbon Dioxide
Describe what happens when metals bond (in terms of ions)
When metals bond, they lose outer shell electrons to leave a full electron shell. This produces a charge atom with a positive charge.
Describe what happens when nonmetals bond with a metal (in terms of ions)
When nonmetals bond with a metal they gain electrons to achieve a full electron shell. This produces a charge atom with a negative charge.
A calcium atom has 20 electrons and an oxygen atom has 8 electrons. Use the electronic structures of Ca and O to explain why calcium oxide has the formula CaO.
Because Calcium gives 2 electrons to Oxygen which creates a positive Calcium ion and a negative Oxygen ion. Being negative and positive, they cancel each other out, so it’s just CaO.
What is an ionic compound?
It means it is a compound made up of a positive metal ion and a negative non-metal ion
What is an acid? (Not talking about pH values)
A compound containing hydrogen that dissociates in water to form hydrogen ions.
What is a base? (Not talking about pH values)
A compound that reacts with an acid to form a salt and water.
What is alumina?
An alternative name for aluminium oxide
What is the chemical formula for alumina?
Al₂O₃
What does amphoteric mean?
It can act as both an acid and a base
What forms when alumina reacts with acids?
Salt + Water
What does chemically inert mean?
Not chemically reactive
Is alumina chemically inert?
Yes
When does alumina react with an acid?
If it is hot because the heat energy helps cause the chemical reaction
What are examples of things that sodium hydroxide is found in?
Soap, plastic, and oven cleaner
What are examples of things that alumina can be found in?
Glass, sunscreen, and paint
What is an alternative name for calcium hydroxide?
Lime
What is calcium hydroxide used for?
It can be used to neutralise acidic soils or to neutralise acidic factory waste
What happens to the electrons in an ionic compound?
The atom that gains the electrons becomes a negatively charged anion, the atom that loses the electrons becomes a positively charged cation
What properties do ionic compounds have?
High boiling/melting point, hard/brittle, good insulators, conduct electricity when dissolved or melted
What creates electricity?
Current
What is a cation?
A positively charged ion which is attracted to the negative cathode during electrolysis
Is the anode positive or negative in electrolysis?
Positive
Is the cathode positive or negative in electrolysis?
Negative
What is electrolysis?
Using electricity to split ionic compounds
What happens at the positive anode?
Oxidation
What is oxidation in electrolysis?
Loss of electrons
What is reduction in electrolysis?
Gain of electrons
What two things can be done to an ionic compound to allow electrolysis to occur?
Either melt it or dissolve it
Why must ionic compounds be melted/dissolved to allow electrolysis?
Ions are free to move so substance conducts an electrical current
What is the name of the positive, and negative electrode?
Positive Anode, Negative Cathode
Why can’t ionic compounds conduct electricity as solids?
Ions aren’t free to move if they’re in an ionic lattice
What is an electrolytes?
A molten or dissolved ionic compound
Why does melting or dissolving a solid ionic compound turn it into an electrolyte?
The ionic lattice is broken down which allows the ions to move freely
In electrolysis, what do we do to the ionic compound the first stage?
Melt it or dissolve it in water
What are the uses of electrolysis?
Making chlorine gas, making hydrogen gas, extracting metals, and making soaps
What are anions?
Negative ions
What are cations attracted to?
Negative electrode (cathode) which is why they move to the cathode where they are discharged
What are anions attracted to?
Anions are attracted to the anode which is why they move to the anode where they are discharged
Where does oxidation happen?
Anode (positive electrode)
What happens at the cathode?
Reduction
What is the positive electrode called?
Anode
What is the negative electrode called?
Cathode
In the electrolysis of molten lead bromide, what is the product at the anode?
Bromine is the product at the anode.
In the electrolysis of molten lead bromide, what is the product at the cathode?
Lead is the product at the cathode.
In the electrolysis of a solution, which ions from water are attracted to the anode?
Hydroxide ions from the water are attracted to the anode.
In the electrolysis of sodium chloride solution, what is the product at the cathode?
Hydrogen
What are the two types of discharge?
Oxidation and reduction
Which ions need to be reduced to discharge them?
Cations
Which ions need to be oxidised to discharge them?
Anions
What does the word “Aqueous” mean?
When a substance is dissolved in water to form a solution
What might be an advantage of aqueous electrolysis instead of molten?
It uses less energy (as no melting is required) however you might get different products
Why are transition metals good conductors of heat and electricity?
Because they are metals
Why are Scandium and Zinc not transition elements?
Their ions don’t form partially filled d-subshells
What is a transition element?
One that forms at least one stable ion with a partially filled d-subshell of electrons.
What is a complex ion?
Metal ion surrounded by co-ordinately bonded ligands
What is a co-ordinate bond?
A covalent bond in which both electrons in the shared pair come from the same atom
What is co-ordination number?
The number of coordinate bonds to ligands that surround a transition metal ion
What is a ligand?
An ion or molecule that forms a coordinate bond with a transition metal
What is a Monodentate?
Ligand that can only form one coordinate bond
What is a bidentate?
Ligand that can form two coordinate bonds
What is a multidentate?
Ligands that can form more than one coordinate bond
Is a co-ordinate bond a type of metallic, ionic, or covalent bond?
Covalent bond
What are half equations used for?
To show whether or not the electrons went through oxidation or reduction
What is reduction?
Gain of electrons in electrolysis
At which electrode does reduction always take place?
Cathode
At which electrode does oxidation always take place?
Anode
What is the equation for heat?
Q = mc△t
(Heat = mass x specific heat x temperature change)
What does the ‘Q’ stand for in heat equation?
Heat
What does the ‘m’ stand for in heat equation?
Mass of water
What does the ‘△t’ stand for in the heat equation?
Change in temperature
How is aluminium ore taken from the ground?
Open cast mining
What is the name of the main ore in aluminium?
Bauxite
What is the definition of an ore?
A rock that contains enough metal for it to be economical to extract
What is a catalyst?
A substance that speeds up the rate of reaction by lowering the activation energy
What happens to the catalyst at the end of the reaction?
Nothing, catalysts are unchanged at the end of the reaction
What is a homogenous catalyst?
When the catalyst is in the same state as the reactants
What is a liquid catalyst and liquid reactants an example of?
Homogenous catalyst
Give an example of a homogenous catalyst
Enzymes in our saliva or blood
What is a heterogenous catalyst?
When the catalyst is a different state from the reactants
What is a solid catalyst and liquid reactants an example of?
Heterogenous catalyst
What is an example of a heterogenous catalyst?
Iron in the Haber process
How do catalysts lower energy demands?
Reduce costs and helps the environment
What is redox?
When a transition metal ion acts a catalyst it changes oxidation state
What is an example of redox?
The Contact Process
What is catalyst efficiency?
The efficiency with which an enzyme converts a given substrate to a given product
What method do you use to react titanium?
The Kroll Method
Why is extracting titanium expensive?
The Kroll method needs to have Chlorine and Carbon heated to 1000℃ which requires a lot of energy.
The product of Mg / Cl₂ by electrolysis needs lots of energy.
The machine must be shut down and cooled before you remove titanium for purification.
Titanium needs purification steps.
Argon atmosphere required
How long does it take to extract Titanium?
Up to 6 months
What is a hydrocarbon?
A compound made up of only hydrogen and carbon atoms
What is a saturated hydrocarbon?
A saturated hydrocarbon is one in which all of the carbon atoms are connected by a single bond
What is an unsaturated hydrocarbon?
A hydrocarbon that has at least one double bond, triple bond, or ring in its carbon chain
What is empirical formula definition?
The empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound
What is the molecular formula definition?
Actual number of atoms of each element in a molecule
What is a displayed formula?
A displayed formula of a compound shows the arrangement of atoms in a molecule as well as the bonds
What is structural formula?
Structural formula of a compound shows how atoms are arranged in a molecule and which functional groups are present
What is skeletal formula?
Skeletal form of a compound shows the bonds between carbon atoms, but not the atoms themselves. Hydrogen atoms are also ommitted but the other atoms are shown
What is a functional group?
An atom or group of atoms responsible for the typical chemical reactions of a molecule
What is a homologous series?
A group of molecules with the same functional group but a different number of -CH₂ groups
What does fission mean?
Breaking of bonds
What is homolytic fission?
Covalent bond breaks and one electron goes to each atom involved in the bond. This forms radicals (highly reactive and neutral)
What is heterolytic fission?
Covalent bond between two chemical species is broken in an unequal manner, resulting in the bond pair of electrons being retained by one of the chemical species
What are monomers?
Monomers are simple molecules that are joined together to form polymers
What is the most widely used plastic?
Polyethene
What is polyethene used for?
Carrier bags, bin liners, making films in packaging
What does Ra· mean?
A variety of radicals
The overlap of orbitals in alkenes results in the formation of two types of bonds. Name these two types of bonds
Sigma and pi
What is an electrophile?
An electron pair acceptor
What is an example of an electrophile?
HBr
What is enthalpy?
The heat content of a system
How can we measure enthalpy?
We cannot measure enthalpy directly, but we can measure enthalpy changes (▵H)
How do you create energy?
Energy cannot be created or destroyed. It can transfer from one place to another
What is the formula for calculating enthalpy change?
△H = △U +p△V
(Enthalpy Change = Internal Energy Change + (Pressure x Change in volume)
What is the symbol for standard enthalpy change?
△Hθ
What is the unit of enthalpy change?
kJ mol⁻¹
What is an endothermic reaction?
When energy is taken in from the surroundings, this is called an endothermic reaction and the temperature of the surroundings decreases.
What is an exothermic reaction?
Reaction that releases energy from chemicals to its surroundings
What are the steps of electrolysis?
- Using direct electrical currents, the ionic compounds are split up into their positive and negative ions.
- Current passes through to move the electrolyte.
- Positive ions move to the Cathode and negative ions move to the Anode.
- Positive ions are reduced at the Cathode as they gain electrons. Negative ions will be oxidised at the anode, as they lose electrons.
- A flow of charge is created by the movement of ions through the electrolyte. Once the ions gain or lose electrons they become uncharged and are then discharged from the electrolyte
What are positive metal ions called?
Cations
What are cations always attracted to?
The cathode
What does a curly arrow within a molecule show?
The breaking of a bond
Is bond making an exothermic or endothermic process?
Exothermic
Is bond breaking an endothermic or exothermic process?
Endothermic
