C4 - Producing and identifying products in chemical reactions (FAREEHA) Flashcards
What are the properties of alkali metals?
- shiny when freshly cut
- soft (softer going down)
- solid at Room Temp
- good conductor
What do alkali metals form when they react with water?
Alkali metals react in water to form alkaline solutions.
What colour are the ionic compounds formed from alkali metals?
white or colourless ionic compounds
Trends in …… for alkali metals. (GOING DOWN THE GROUP)
- Reactivity
- MP / BP
- Density
Reactivity increases (going down the group);
valence electrons are further from the nucleus, so it is easier to loose - weaker electrostatic forces of attraction
Melting point decreases (going down the group);
more shells, so delocalised electrons are further from the nucleus - weaker electrostatic forces of attraction
Density increases (going down the group);
more shells, denser
Explain how Lithium, Sodium, Potassium react in water.
- Lithium fizzes steadily and slowly disappears.
- Sodium melts to form a silvery ball, fizzes vigorously and then quickly disappears.
- Potassium immediately ignites, burns with a lilac flame and very quickly disappears.
What are the properties of the halogens?
- Brittle
- Poor conductors
- Diatomic molecules
Halogens can displace halides in solution
What do fluorine, chlorine, bromine and iodine look like at RM?
Fluorine - pale yellow gas
Chlorine - green gas
Bromine - orange-brown liquid
Iodine - shiny grey-black crystalline solid
What do halogens and metals react to form?
Halogen + metal -> salt
Trends in …… for the halogens. (GOING DOWN THE GROUP)
- Reactivity
- MP / BP
- Density
Reactivity decreases (going down the group);
more shells, valence shell further from nucleus, so harder to gain electrons - weaker electrostatic forces of attraction
Melting point increases (going down the group);
more shells, larger molecules, so the Intermolecular forces of attraction are stronger
Density increases (going down the group);
more shells, denser
Describe the properties and trends of the noble gases (GROUP 0)
they are unreactive (no tendency to loose/gain electrons as they already have full outer shells - stable)
their MP and density increases going down the group
Describe the properties of the transition metals.
- strong; malleable; shiny when freshly cut
- good conductors
- stronger harder higher MP than group 1
- good catalysts
- less reactive than g1 and g2
- can form 2+ or 3+ charges
- form coloured ionic compounds
Describe the general trends in reactivity for metals
and reacting metals with water/dilute acid.
MOST REACTIVE <-> LEAST REACTIVE
group 1 , group 2 , transition metals
metals can react with water or dilute acid if it is more reactive than hydrogen
metal + acid -> salt + hydrogen
metal + water -> metal hydroxide + hydrogen
List reactivity series.
Potassium, Sodium, Lithium G1 (Lowest first)
Calcium, Magnesium G2 (lowest first)
Aluminium G3
Carbon G4
Zinc, Iron, Tin, Lead Transition Metals
Hydrogen
Copper, silver, gold, platinum
How can you test if Carbon dioxide is present?
bubble the gas through limewater
The Limewater (Calcium hydroxide) will turn cloudy white if Carbon dioxide is present
calcium hydroxide + carbon dioxide -> water + calcium carbonate (White precipitate)
How can you test if Chlorine is present?
Chlorine dissolves in water to form acidic solutions and bleaches dyes.
1. dampen blue litmus paper
2. hold to container
3. is chlorine is present, the paper will turn from blue to red then white
How can you check if hydrogen is present?
hold a lighted splint to the test tube, it will ignite with a squeaky pop if present
How can you check if oxygen is present?
hold a glowing splint to the test tube, it will relight if present
How does a flame test work?
When metal ions are heated, energy is transferred to their electrons, so they move to higher electron shells. When they move back, energy is transferred to the surroundings as radiation (light).
Flame test table
Lithium - Red
Sodium - Yellow
Potassium - Lilac
Calcium - orange red
Copper - green blue
Precipitate colour table (Reacting with hydroxide precipitate)
Iron (II) - green
Iron (III) - orange-brown
Copper (II) - blue
Calcium - white
Zinc - white (but dissolves in excess)
How can you test for the presence of sulfate ions?
Barium reacts with sulfate ions to produce barium sulfate (white, insoluble precipitate)
1. add a few drops of dilute hydrochloric acid
2. add a few drops of barium chloride solution
if present, white precipitate
How can you test for the presence of carbonate ions?
carbonate + hydrogen -> carbon dioxide + water
1. add a few drops of dilute hydrochloric acid
if present, bubbles of gas (CO2) produced
How can you test for the presence of halide ions? (and identify them)
1, add few drops of nitric acid
2. few drops of silver nitrate solution (PRECIPIATE COLOUR)
Chloride - white
Bromide - cream
Iodide - yellow
what is an instrumental method of analysis?
It relies on a machine to carry out an analysis of a substance
what are the advantages of instrumental methods of analysis?
- sensitivity (can analyse very small amounts)
- accuracy (accurate, can be calibrated)
- speed (fast analysis 24/7)
How can you read a chromatogram?
- peaks represent different components
- the area under the peak is the relative amount
- the retention time is individual to each substance like Rf
What does a mass spectrometer do?
measures masses of atoms and molecules, and analyses relative amounts of different isotopes of elements and their structure
how to read mass spectra?
each peak reps fragment of molecule
peak on far right - molecular ion
the mass to charge ratio of the molecular ions equals Mr of substance
