C8 - Reactivity Trends Flashcards
What state are each of the halogens in at room temp (F, Cl, Br, I)
F - gas
Cl - gas
Br - liquid
I - solid
What does F look like at room temp
Very pale yellow gas
What does Cl look like at room temp
greenish gas
What does Br look like at room temp
red liquid
What does I look like at room temp
shiny grey solid
What is the trend in melting point for group 7 elements?
Melting point increases down the group
Bigger molecules, more electrons, stronger london forces
more energy required to overcome
The halogens higher in the group (F and Cl) are MORE POWERFUL ___ ___ than those lower in the group (Br and I)
oxidising agents
State and explain the role halogens play in redox reactions
Oxidising agents
They gain electrons (so are reduced - RIG) meaning they oxidise the other species
During a displacement reaction, chlorine becomes the free halogen. What colour is the solution in the test tube?
Very pale green (often colourless)
During a displacement reaction, bromine becomes the free halogen. What colour is the solution in the test tube?
Yellow
During a displacement reaction, iodine becomes the free halogen. What colour is the solution in the test tube?
Brown (sometimes black solid)
A displacement reaction occurs between a halide and a halogen, the colour of the solution is not immediately obvious, what could you do to change this?
Add an organic solvent and shake, a coloured precipitate will form in the solvent clearly indicating the free halogen
During a displacement reaction, chlorine becomes the free halogen. An organic solvent is added. What colour is the solution in the solvent?
colourless
During a displacement reaction, bromine becomes the free halogen. An organic solvent is added. What colour is the solution in the solvent?
Yellow
During a displacement reaction, iodine becomes the free halogen. An organic solvent is added. What colour is the solution in the solvent?
purple
Reaction of a group 2 element with oxygen makes…
Group 2 oxide (eg. CaO)
Reaction of a group 2 element with water makes…
Group 2 hydroxide and hydrogen
Reaction of a group 2 element with acid (HCl) makes…
Group 2 chloride and hydrogen
What would the products be from a reaction between Calcium and oxygen be?
Calcium oxide
What would the products be from a reaction between Calcium and water be?
calcium hydroxide and hydrogen
What would the products be from a reaction between Calcium and hydrochloric acid be?
Calcium chloride and hydrogen
What 3 reactions do you need to know for group 2 elements
Group 2 + oxygen
Group 2 + water
Group 2 + acid
What is the trend in the solubility of group 2 elements
Solubility increase down the group
State and explain the trend in pH of group 2 hydroxides
More alkaline (pH increases) down the group as the hydroxides are more soluble so more free OH- ions
Group 2 oxides + water makes…
Group 2 hydroxides + hydrogen
State 2 uses of group 2 compounds
agriculture- decrease acidity of soil
medicine - acid indigestion - neutralise some acidic fluids
H2O + Cl2 —>
HCl + HOCl (reversible)
2NaOH + Cl2 —>
NaCl + NaOCl + H2O
Describe how you would Distinguish which he lied you had in a compound
Add AG plus ions (silver nitrate). Precipitate formed
AgCl = white (dissolves in dilute NH3)
AgBr = cream (dissolves in conc NH3)
AgI = yellow (does not dissolve in NH3)
What is the test for carbonate ions
Add dilute nitric acid, CO2 will be evolved, effervescence.
What is the test for sulphate oils
Add Ba2+, white precipitate will form, sulfates soluble in water except barium sulphate
What is the test for ammonium irons
Add an NaOH, NH3 gas will be formed when warmed, damp litmus paper will turn blue
