Chemical Changes Flashcards (4)
What is oxidation
Oxidation is loss of electrons, gain of oxygen or loss of hydrogen
What is reduction?
Reducation is gain of electrons, loss of oxygen or gain or hydrogen.
What is the reactivity series of metals?
The series shows the metals in order of their reactivity.
How do you remember the reactvity series
What does the polite reprsent in the reactvity series
potassium (K)
What does the spotted reprsent in the reactvity series
sodium (Na)
What does the leopard reprsent in the reactvity serie
Lithium Li
What does the can reprsent in the reactvity serie
Calcium Ca
What does the meet reprsent in the reactvity serie
Magnesium Mg
What does the affectionate reprsent in the reactvity serie
Aluminium Al
What is inbetween Alminium and zinc in the reactvity series
Carbon C
What does the zebra reprsent in the reactvity serie
Zinc Zn
What does the into reprsent in the reactvity serie
Iron Fe
What does the tender reprsent in the reactvity serie
Tin Sn
What does the loving reprsent in the reactvity serie
Lead Pb
Whats inbetween Lead(Pb) and Copper(Cu)
Hydrogen (H)
What does the care reprsent in the reactvity serie
Copper Cu
What does the single reprsent in the reactvity serie
Silver Ag
What does the girls reprsent in the reactvity serie
gold (Au)
What does the please reprsent in the reactvity serie
Platinum
What the reactvity series order from most to least reactvie
Potassium K
Sodium Na
Lithium Li
Calcium Ca
Magnesium Mg
Aluminium Al
Carbon C
Zinc Zn
Iron Fe
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Silver Ag
Gold Au
Platinum Pt
What happens to metals above H( 2 ) and those in the reactvity series
Metals above H( 2) in reactivity series react with acid to produce H(2).The more reactive the metal is, the quicker and more violent reaction with acid occurs.
What happens to metals bellow H(squared 2 ) and those in the reactvity series
Metals below H(squared 2) don’t react with acids.
Do all metals above H2 react with water
Mostly group 1 and 2.Aluminium is the borderline case.
What is a displacement reaction?
A reaction where a more reactive metal (in the reactvity series) displaces a less reactive metal from a compound
How are unreactive metals found in Earth?
In their natural state (well, they are unreactive…)
How can metals less reactive than carbon be
extracted?
Reduction with carbon. Carbon displaces the metal in a metal oxide - gets oxidised to carbon oxides. Metal from the metal oxide gets reduced to the pure metal.
How are metals more reactive than carbon extracted?
By electrolysis
How are oxidation and reduction defined in terms of electron transfer?
Oxidation – loss of electrons
Reduction – gain of electrons
What is the general equation for a reaction between metals and
acids? What type of reaction is this?
Which metals in the reactivity series will react with acid?
Those above hydrogen
What is the general equation for a neutralisation reaction?
What is the general equation for the reaction between metal carbonate and acid?
What is the general equation for the reaction between metal oxides
and acids?
What is a redox reaction?
A reaction where both oxidation and reduction occurs
Explain in terms of gain or loss of electrons which species has been oxidised and which species has been reduced when magnesium reacts with hydrochloric acid
Magnesium has lost electrons and thus has been oxidised (Mg to Mg2+(squared)
The hydrogen in HCl has gained electrons and thus has been reduced (H+ to H2 (squared)
How is a soluble salt formed?
a) React the excess acid with some insoluble chemical (e.g. metal oxide)
b) Filter off the leftovers
c) Crystallise the product
What do acids and alkalis produce in aqueous solutions? Interms of hydrogens
Acids produce hydrogen ions,
alkalis produce hydroxide ions
What are bases, acids and alkalis?
Bases are compounds that neutralise acids
acids produce hydrogen ions in aqueous solutions
alkalis are soluble bases - produce hydroxide ions in aqueous solutions
What is the pH scale and what does a pH of 7 show?
The measure of acidity/alkalinity of a solution; neutral solution
State the general equation for a neutralisation reaction in a short, ionic form.
What is a strong acid? What is a weak acid?
Strong acid is completely ionised in aqueous solution; weak acid is only partially ionised in aqueous solution
What happens to pH as concentration of H+ increases?
The pH decreases
What is a concentrated acid and what is a dilute acid? Is this the same as a strong and weak acid?
- Concentrated acid has more moles of acid per unit volume than dilute (dilute refers to solutions of low concentrations)
- It is not the same - concentration is not the same thing as strength of an acid.
- Strength refers to whether the acid is completely ionised in water (strong) or
only partially (weak).
As the pH is decreased by one unit, what change is seen in the
hydrogen ion concentration?
Increases by a factor of 10
Name this salt
Lithium nitrate
Name this salt
Potassium carbonate
Name this salt
Magnesium bromide
Name this salt
Barium sulfate
What is electrolysis?
The passing of an electric current through ionic substances that are molten or in solution to break them down into elements
ions are discharged (they lose/gain electrons) at electrodes to produce these
What is an electrolyte?
The liquid/solution which conducts electricity
What is a cathode and what is an anode?
Cathode is the negative electrode, anode is the positive electrode
What occurs at the cathode in electrolysis ?
Reduction occurs at the cathode
What occurs at the anode in electrolysis ?
Oxidation occurs at the anode
In aqueous electrolysis, which element is discharged at the cathode?
The less reactive element discharges at the cathode. Hydrogen is produced unless there is a less reactive metal, in which case the said metal is produced.
Oxygen is produced at the anode unless what?
Oxygen is produced at the anode unless the solution contains halide ions, in which case halogen molecules are produced.
How is aluminium manufactured?
Aluminium is made through the electrolysis of aluminium oxide and cryolite.
Why is aluminium expensive to manufacture
Lots of energy is needed to produce the current in electrolysis which makes this process expensive.
What are the half equations in the extraction of aluminium?
Why is cryolite used in manufacturing of aluminium?
It lowers the melting point of aluminium oxide, reducing energy costs
What are the half equations in electrolysis of the aqueous Na2(squared)SO4(power of 4)?
What are the half equations in electrolysis of the molten and aqueous KCl?
What are the half equations in electrolysis of the aqueous CuBr2?
