Chemistry-2 (Elements of Life) Flashcards
Colour change of phenolphthalein from acid to alkali
Red/ pink to clear
Colour change of methyl orange from acid to alkali
Yellow to red
What shape is the s orbital?
Spherical
What shape is the p orbital?
Dumbbell
What is a dative covalent bond?
When the electrons come from the same atom
2 special cases of covalent bonding
BF3 boron only has 6 outer electrons not 8
SF6 sulfur has 12 outer electrons not 8
Angle size of tetrahedral molecule
109.5
Angle size of water
<109.5
104.5 due to lone pairs
Draw a standard first ionisation enthalpy equation
X(g) —> x+(g) + e-
Relationship of first ionisation enthalpy down group 1 and 2
Decreases
First ionisation enthalpy trend across periods
Increases
First ionisation enthalpy of group 1 high or low
Low
How to detect carbonates?
Dilute HCl and carbonates will fizz and produce CO2
Then test for CO2 with lime water which will turn cloudy if present
How to test for sulfates?
Add dilute HCl follow by Barium Chloride
If it forms a white precipitate of barium sulfate
( HCl added to get rid of traces of carbonate ions)
Test for ammonium compounds
Ammonia gas is like an alkaline so can be checked using a damp piece of red litmus paper and will turn blue if present
How to test for hydroxides?
Litmus paper
Red litmus paper will turn blue
Test for halides
Add silver nitrate
Cl- Chlorine will form white precipitate
Br- Bromine will form cream precipitate
I- Iodine will form yellow precipitate
How is energy related to frequency
E= hv
Plancks constant x freq
E= hc/ w
Plancks constant x speed of light/ wavelength
Define elimination reaction
When a molecule is removed. Product becomes unsaturated. Double bond formed.
Flame test for lithium
Crimson
Flame test for sodium
Yellow
Flame test for potassium
Lilac
Flame test for calcium
Red
Flame test for barium
Green
Flame test for copper
Blue- Green
Coloured precipitate by adding sodium hydroxide (NaOH) to Silver Ag 2+
Brown
Coloured precipitate by adding sodium hydroxide (NaOH) to Calcium Ca2+
White
Coloured precipitate by adding sodium hydroxide (NaOH) to Copper (II) Cu 2+
Blue
Coloured precipitate by adding sodium hydroxide (NaOH) to Lead (III) Pb 2+
White
Coloured precipitate by adding sodium hydroxide (NaOH) to Iron (II) Fe 2+
Green
Coloured precipitate by adding sodium hydroxide (NaOH) to Iron (III) Fe 3+
Brown
Coloured precipitate by adding sodium hydroxide (NaOH) to Zinc Zn 2+
White, in excess of NaOH is colourless
Coloured precipitate by adding sodium hydroxide (NaOH) to Aluminium Al 3+
White, in excess of NaOH will turn colourless
Describe metallic bonding
Between metals Sea of delicalised electrons Conduct Insoluble High MP 2+ higher than 1+
Describe ionic bonding
Metal and non metal Electrons transferred High MP Soluble Conduct when molten
Describe ionic bonding
Metal and non metal Electrons transferred High MP Soluble Conduct when molten
Describe simple covalent bonding
Between non metals Share electrons Low MP Don't conduct Insoluble
Describe giant ionic lattices
Eg NaCl
Very high MP
Many ionic bonds
Describe giant covalent bonding
Mainly carbon and silicon Don't conduct except graphite High MP Thermal conductors Insoluble
How to calculate percentage composition?
Mass of element/ total mass of compound x100
How to calculate empirical formula from percentage composition
Percentage, pretend it’s in 100g,
1) Divide percent by Mr of element.
2) Divide by smallest number
