REDOX Flashcards
Reduction
The gaining of electrons
Oxidation
The loss of electrons
Oxidant
Gains electrons
Reductant
Loses electrons
Eg of Reduction (Including Oxidant)
Cu 2+ (aq) + 2e- -> cu (s) Cu 2+ is oxidant
Eg of Oxidant (Including Reductant)
Fe (S) -> Fe 2+ (aq) + 3e- Fe is reductant
Electrolyte
Solutions that allows ion movments
Anode
A Postive Electrode
Cathode
A negative Electrode
3 types of observations which may be made to indicate that a spontaneous redox reaction has occured
Bubbles at electrode
Colour Change
Deposit of metal on electrode
Conjugate redox pairs (ZN as a reductant)
Zn2+
Conjugate redox pairs (Fe2+ as a reductant)
Fe3+
Would it be sensible to store copper (II) sulfate in an iron tank?
Cu 2+ (aq) + Fe -> Cu (s) + Fe 2+
Cu 2+ is the strongest oxidant and Fe is the strongest reductant. Fe will decompose into Fe 2+ allowing cu2+ to break out. It would not be sensible
Conjugate of bases
loses Hydrogen atoms
Conjugate of Acids
gains Hydrogen atoms
Amphiprotic
Able to act as both an acid and base
What is a weak/ Tiprotic acid?
When its weak it means that it does not release H+ readily and Triprotic means that it is ready to donate 3H+ from the substance.
State the Bronsted- Lowry definitions of both an acid and base.
Acids donate Protons and base accepts protons
What is it meant by a strong acid
Low on the Ph scale and they are more ready to donate protons. They also have high amount of H+ atoms. eg h2so4
What is it meant by a strong base
Higher Ph and are more ready to accept protons. and with more OH-. eg is Nacl2
Show that H3PO4 is polyprotic
H3Po4+ H2o -> H2Po4 + H3O (INCLUDE STATES)
Water has a high surface tension
The water molecules attract one another due to the water’s polar property. Insects can walk on the surface of water because of surface tension of water
Water has a high heat of vaporisation.
a high input of energy is required to transform one gram of liquid water into water vapor, an energy requirement called the heat of vaporisation
Copper (II) Carbonate crystals are added to dilute sulphuric acid
CuCo3 (s) + H2So4 (aq) -> Co2(g) + Cuso4 (aq) + H20 (l)
Co2 bubbles forming would of seen the solution turn blue
Show that a reaction between mg and hcl is a redox equation
The Mg reductant is oxidised by H+
Q=mc^T
100 g of water at 25.00 degrees absorbs 100J of heat. What is its final temp?
100 divided by (100x 4.18) = 0.24 Degrees
25 degrees plus 0.24 equals 25.2 degrees
Q= mc^T
80g of acetone was heated from 25.5 degrees to 63.4 degrees. how much energy was transferred to the acetone during heating?
SHC of acetone = 2.13jg -1
80 x 2.13 x 37.9 = 6458.16 j
= 6.46 KJ of enegry
C=
n divided by v
Properties of a acid
Tastes sour, Molecular in structure, Forms conducting soloutions
What is least likely to act as an acid
A Structure that has non polar bonds
When an alkaline solution with a pH of 8 has a large volue of water added to it , the pH will
Fall as the concentration of the OH- ion has decreased
Which of the following lists the solutions in order of increasing pH
H2sO4, HNo3, Ch3COOH, H2O, NH3, NaOh
The pH of 25.0ml of solution of nitric acid (HNo3) is closest to
[h3o+] = -log(0.002)
Hydrolysis
One which a substance reacts with water to form OH- or H3O+ ions.
Acid- Base
Protons are being donated to OH- Ions
Ionisation
when a substance reacts with to produce.
[ OH-]
10^-14 divided by 10^ pH
[H30+]
M= 9,2x 10^14
M+ -log(9.2x10^-14 =3
Why is Ethanoic acid (CH3C00H) Monoprotic even though it has 4 hydrogen atoms
Because one hydrogen is in a polar bond which can be donated and 3 are not in a polar bond therefor cannot be donated
Equation and observation of MgO powder being added to dilute HCL
MgO (s) + 2HCl (aq) -> H2O (l) + Mgcl2 (aq)
The solid powder would disappear
the Ph of a 0.010M solution of a strong DIprotic acid will be
between 1.7 and 2.0 as the second proton is only partially donated.
- log(0.01) =2
- log (0.02) = 1.7
Neutralisation
The process of an acid reacting with a base. the properties of the acid and base can be cancelled out.
Pepitte (Aliquot)
used to transfer fixed volume of solution to conical flask. Rinse with solution that it will transfer
Conical Flask
Receives the aliquot. Add 1-2 drops of indicator. Rinse with distilled water
Standard Flask
Always used to prepare solution of known concentration.
Rinse with distilled water
Burette
Delivers variable volume. Rinse with solution that it will contain
Polyprotic Acids
An acid that can donate more than one proton.
Self Ionisation of water
Since water can act as both an acid and base, it can also react with itself according to the equation
H2O (l) + H2O (l) -> H3O= + OH-
Why is a nuetral solution a pH of 7
Because it has an equal amount of [H+] and [OH-] Ions.
Dilution: calc volume of
0.250x 2.15 Divided by 12
Standerd Solution
It must have a high state of purity
It must have an accurately known formula
It must be stable
Calculate Concentration in gL-1 and mgL-1 for
0.425g Barium Nitrate in 25 ml of solution
25 divided by 1000 = 0.055
0.425 divided by 0.055.
= 480gL-1 and or 4.8x10^-14 mgL-1
Corrosion
Oxidation of metals by materials in their enviroment
Dry Corrosion
When a metal reacts differently with oxygen. K and Na combine readily with oxygen so they undergo dry corrosion quickly
Wet Corrosion rusting
When a metal reacts with oxygen in the presence of water. Water can speed up corrosion reactions.
Fe (s) -> Fe 2+ (aq) +2e-
Adverse effects of corrosion
A severly corroded metal cannot conduct electricity.
Products of corrosion are brittle and flake off.
Metal oxides have less tensile strength.
Corrosion Protection
Surface Protection
Alloying
Electrochemical Protection
Surface Protection + equation
A metal surface being prevented from being into contact with oxygen, such as using oil.
Alloying + equation
Iron can be alloyed with small quantities of metals such as chronium, nickel, manganse to produce stainless steel
Electrochemical Protection + equation
placing a more reactive metal in a electrical contact with the metal that needs protection
Zinc and Copper2+ Displacement reaction
When zinc was placed in copper sulfate solution a reaction occurs, causing copper metal to form Zinc.
Zn (s) + Cu2+ (aq) -> Zn2+ (aq) + Cu (s)
Concentration dosent determine strength. it is based on
the amount of ions and how much acid in the solution
Chemical equation of ethonaic acid reacting h20
Ch3CooH+ H20 -> Ch3COO- + H30+
Nuetralisation equation
HCL (aq) + NaOH (aq) -> NaCl (aq) + h20
Ionic equation of nuetralisation
H3O + (aq) + OH- (aq) - 2H20 (l)
Corrosion of Iron
2Fe(s) + O2 (g) +2h2o (l) -> 2Fe(OH)2 (s)
Copper and Zinc 2+ reaction
No reaction would occur. this makes zinc more reactive
Calculate pH of solution Ca(OH)2
10^-14 divided 0.02 then -log( )
