Elements Of Life Flashcards
Which of Lead Chloride, lead bromide, copper iodide, and lead iodide is yellow?
Lead iodide
The rest are white
What colour is copper carbonate?
Blue/Green
What colour is silver carbonate?
Yellow
What colour are most carbonate precipitates?
White
How do you get pure salt from a precipitation reaction?
1) wait for it to precipitate out
2) filter
3) wash
4) dry on filter paper
What do you need to make a soluble salt
Metal or insoluble base (metal hydroxide or oxide)
What does ‘spin pairing’ mean?
Electrons in orbitals ‘spin’ in opposite directions
What is the shape of a molecule with 2 electron pairs?
Linear
What is the shape and how many electrons can:
1) an S orbital hold?
2) a p orbital hold?
3) how many electrons can a D orbital hold?
1) sphere - 2 electrons
2) dumbbell - 6 electrons
3) 10 electrons
What are the shapes of a molecule with 3 electron pairs?
1) without a lone pair?
2) with a lone pair?
1) trigonal planar
2) bent
What are the shapes of a molecule with 4 electron pairs?
1) no lone pairs
2) 1 lone pair
3) 2 lone pairs
1) tetrahedral
2) trigonal pyramidal
3) bent
What shape would a molecule with 5 electron pairs have?
Trigonal bipyramidal
What shape would an electron with 6 electron pairs have?
Octahedral
Which metal ions precipitation starts white and redissolves to colourless?
Zinc(II) and aluminium(III)
How do group 2 elements produce metal hydroxides
1) react with water
Or
2) burn in oxygen to form metal oxide and then dissolve to form metal hydroxide
What group 2 type breaks down into CO2 and metal hydroxides?
Group 2 carbonates
What are the solubility trends of group 2
1) hydroxides
2) carbonates
1) less soluble down the group
2) more soluble down the group
What is the trend in thermal stability of group 2 carbonates?
More stable down the group
What reactions show that group 2 oxides are a base?
1) react with water to form hydroxides - very alkaline
2) neutralise acids
What do group 2 carbonates decompose to?
Group 2 oxide and CO2
What reaction makes salts?
Neutralisation reaction with an acid and a base
Which of a cation or anion is positive or negative?
Cation = positive (cats) Anion = negative
What is the formula of the ammonium cation?
NH4+
What is the formula of nitrate?
NO3-
What is OH- called
Hydroxide
What is the formula of a sulfate
SO4^2-
What colour is a silver ion in as a precipitate? Ag+
Brown
What colour is a calcium ion (Ca^2+) as a precipitate?
White
What metal ion is has a blue precipitate?
Copper
Cu^2+
What metal ion has a green precipitate?
Iron (II)
Fe^3+
What colour is a lead ion as a precipitate? Pb^2+
White
What metal ion has a reddish brown precipitate?
Iron (III)
Fe^3+
How do you test for a coloured precipitate of a metal ion?
Metal ion + hydroxide solution (NaOH)
Forms an insoluble metal hydroxide which has a coloured precipitate which can be used to identify metal ion
What are the two ways to test for ammonium compounds?
1) damp red litmus paper to test for ammonia gas - paper will go blue if ammonia is present because it’s alkaline
2) Ammonium ions - add NaOH and gently heat ammonia gas is given off which can be tested with red litmus paper
What is a test for hydroxides
Red piece of litmus paper into solution - OH- is alkaline so paper will go blue if present
How do you test tor nitrates?
1) warm solution with NaOH and aluminium foil (aluminium to reduce nitrate ions to ammonium ions)
2) NH4+ reacts with OH- to form ammonia gas and water
3) test for ammonia with damp red litmus paper
4) if ammonia is present it contains nitrate ions
What colour is a barium ion (Ba2+) in a flame test?
Apple green
What does a blue green flame in a flame test mean?
Copper ions
Cu2+
What does a crimson flame mean in a flame test?
Lithium (Li+)
What colour is a potassium ion in a flame test?
Lilac
What colour is a sodium ion in a flame test?
Orange-yellow
What colour is a calcium ion in a flame test?
Brick red
How do you test for sulfate ions?
Add dilute HCl followed by barium chloride solution (BaCl2)
If a white precipitate forms sulfate is present (precipitate is barium sulfate)
What are the results of the test of halides with silver nitrate solution
Chloride = white Bromide = cream Iodide = yellow
What order should you do tests for to avoid false positives?
Carbonates —> sulfates —> halides
How do you carry out a flame test?
1) dip a nichrome wire loop in conc HCl
2) dip loop in sample of compound
3) hold in clear blue flame
4) observe colour change
What two solutions do you need to test to test for halides?
Dilute nitric acid (removes sulfate ions) and then silver nitrate solution
How do you test for metal ions?
Add a few drops of NaOH to a solution of the compound to form an insoluble metal hydroxide
What is the order of electromagnetic radiation? In increasing frequency and decreasing wavelength
Radio waves Micro waves Infrared radiation Visible light Ultra Violet Xrays Gamma rays
How do electrons move energy levels?
Absorb energy to move up energy levels
Release energy to move down
(Fixes amounts of energy)
What does an absorption spectra look like?
Coloured background with black lines
Corresponding to the frequencies in order to change energy level
What does an emission spectra look like?
Black background with coloured lines
Equation for energy
E= hv
Energy (J) = h x frequency (Hz)
Equation for wavelength
Wavelength (m) = c/frequency
What is nuclear fusion?
How much energy does it release?
When two small nuclei combine under high pressure and temp (usually in stars)
Releases a lot of energy
Why do lines on an absorption and emission spectra get closer together at higher frequencies?
Energy levels get closer together with increasing energy
What salts are insoluble?
Carbonates Apart from Lithium Ammonium Potassium and Sodium (LAPS) Or copper or silver (Copper carbonate is blue-green Silver carbonate is yellow)
What salts are soluble?
Lithium Ammonium Pottasium Sodium (LAPS)
Nitrates
Most chlorides bromides and upsides (not leads or silver halides)
Most sulfate (not barium calcium or lead)
How can you test for carbonates?
HCL + carbonate
Produces CO2 which turns lime water cloudy
What is the formula of carbonate
CO3^2-
What is the formula of hydrogen carbonate?
HCO3^2-
What is the equation to calculate percentage yield?
Percentage yield = (actual yield/theoretical yield) x 100
What is the ionic equation for a halide reaction with silver nitrate solution that produces a yellow precipitate?
Ag+ + I- —> AgI
What is the ionic equation for a halide reaction with silver nitrate solution that produces a cream precipitate?
Ag+ + Br- —> AgBr
What is the ionic equation for a halide reaction with silver nitrate solution that produces a white precipitate?
Ag+ + Cl- —> AgCl
What is an ionic reaction?
A reaction which show how dissociated ions react
