Emergency learn Flashcards
What’s the oxidation number of O in OF₂?
+2
What’s the oxidation number of O in H₂O₂?
-1 (as it’s a peroxide)
What’s the oxidation number of H in NaH?
-1
Defn oxidation number
The oxidation number of an element is the charge an element has or appears to have when it is in a compound when certain rules are applied.
What’s the oxidation number of Group 7 elements?
-1 (but more electronegative +1)
What’s the oxidation number of H?
+1
How does the oxidation number of a reducing agent change during a redox reaction?
Is oxidised so the oxidation number will increase.
How do strong acids differ from weak acids in their behaviour in water according to the Arrhenius theory?
S: Fully dissociates to give hydrogen ions in solution.
W: Only slightly dissociates to give hydrogen ions in solution.
How do strong acids differ from weak acids in their behaviour in water according to the Bronsted-Lowry theory?
S: Good proton donor
W: Poor proton donor
Is the conjugate base of a strong acid or weak acid stronger?
Weak acid
What is an alkali?
A base that is soluble in water.
Give a problem with Arrhenius’ theory.
Excluded common bases such as NH₃.
Defn salt
A salt is formed when the H+ of the acid is replaced by a metal ion or ammonium ion.
Acid + Metal →
Salt + H₂
Acid + Metal oxide/hydroxide →
Salt + H₂O
Acid + Metal carbonate/hydrogen carbonate →
Salt + H₂O + CO₂
Metal + oxygen gas →
Metal oxide
Reactive metal + water →
Metal hydroxide + hydrogen gas
If Cl-, is there more or less electrons than Cl?
More
Name an instrument used to detect radiography.
Geiger-Muller tube
Give 3 uses of radioisotopes.
- Nuclear power
- Cancer treatment (using cobalt-60)
- Sterilisation (by radiation)
Give an example of alpha, beta and gamma emitters.
A: Americium-241
B: Carbon-14
G: Cobalt-60
Phosphate ion
PO₄³⁻
Manganate ion
MnO₄⁻
Hypochlorite ion
ClO⁻
Hydrogencarbonate ion
HCO₃⁻
Nitrate ion
NO₃⁻
Carbonate ion
CO₃²⁻
Why do metals generally have high electronegativity values?
As they are electropositive
Defn ionic bond
Formed due to the electrostatic attraction between oppositely charged ions caused by the complete transfer of electrons from one atom to another.
Why are ionic compounds crystalline?
Because they are made up of an orderly arrangement of oppositely charged ions which give rise to a lattice structure.
Why are ionic compounds solid?
There are extremely strong attractions between the oppositely charged ions which hold the ions tightly together giving a solid structure.
Why do ionic compounds have high boiling points/melting points.
The extremely strong attractions between the oppositely charged ions require large amounts of energy to break, hence ionic compounds have high b.p/m.p.
Give a sample of a flocculating agent.
Aluminium sulphate
Are ionic compounds soluble in polar compounds such as H₂O?
Yes
Why are ionic compounds soluble in polar solvents?
As the attraction between the ions in the compound and polar water are strong enough to pull the crystalline lattice apart.
Inert =
Unreactive
Defn pure covalent bonding
Occurs when electrons are shared equally between atoms.
Defn polar covalent bonding
Occurs when electrons are shared unequally between atoms.
Give 4 properties of covalent compounds.
- Usually gases or liquids
- Do not conduct electricity
- Insoluble in polar water
- Low melting and boiling points
Ionic bonding (table)
- Permanent dipole
- Ionic attractions
Pure covalent (table)
- Temporary dipole
- Van der Waals forces
Polar covalent (table)
- Permanent dipole
- Dipole-dipole attractions
Water, ammonia and hydrogen fluoride (table)
- Permanent dipole
- Hydrogen bonding
Defn polar molecule
The slight positive and slight negative poles of a molecule do not coincide.
Give two examples of molecules with polar bonds that are non-polar molecules.
- BH₃
- CH₄
Is the bonding in BF₃ ionic as expected?
No, sharing occurs
Why do ionic substances conduct electricity when molten or dissolved in water but not in the solid state?
Molten: ions are free to move
Solid: Ions not free to move
The diagram shows a thin stream of liquid flowing from a burette. A stream of water is deflected towards a positively charged rod whereas a stream of cyclohexane is undeflected. Account for these observation.
Polarity of water causes attraction to charged tod and non-polarity of cyclohexane means it is not affected by charged rod.
The diagram shows a thin stream of liquid flowing from a burette. A stream of water is deflected towards a positively charged rod whereas a stream of cyclohexane is undeflected. Explain what would happen in the case of the stream of water if the positively charged rod were replaced by a negatively charged rod.
Stream of water still attracted to rod as molecules arrange themselves with positive pole towards rod.
Defn hydrogen bonding (inter force of attraction)
A force of attraction thar occurs between molecules when hydrogen is bonded to a smaller more electronegative element such as O, F or N.
2 b.p, 2 l.p
V-shaped
4 b.p, 0 l.p
Tetrahedral
3 b.p, 0 l.p
Triangular planar
3 b.p, 1 l.p
Pyramidal
2 b.p, 0 l.p
Linear
Linear bond angle
180°
V-shaped bond angle
104.5°
Triangular planar bond angle
120°
Pyramidal bond angle
107°
Tetrahedral bond angle
109°
What is Kc dependent on?
Temperature
Which word, reaction ‘shifts’ to or ‘moves’ to?
SHIFTS!
Write an equation for the manufacture of ammonia.
N₂ + 3H₂ ⇌ 2NH₃
What name to the process of the manufacture of ammonia?
Haber process
What are the ideal conditions for the Haber process?
Low temp, high pressure
Catalyst used in the manufacture of sulfuric acid.
Vanadium pentoxide
What is the effect of a catalyst on a reversible reaction?
Increases rate for both - reaches equilibrium faster
Colour flame of sodium
Amber/yellow
Colour flame of potassium
Lilac
Colour flame of copper
Blue/green