Group 7 - The Halogens Flashcards
What colour is F2 at room temperature?
Pale yellow
What is the physical state of F2 at room temperature?
Gas
What colour is Cl2 at room temperature?
Green
What is the physical state of chlorine at room temperature?
Gas
What colour is Br2 at room temperature?
Red-brown
What is the physical state of Br2 at room temperature?
Liquid
What colour is I2 at room temperature?
Grey
What is the physical state of I2 at room temperature?
Solid
What is the trend in boiling points of halogens down a group?
Increases
Why does the boiling point increase down a group?
Due to the increased strength of the Van der Waals as the relative mass of molecules increases
What is the trend in electronegativity down a group of halogens?
Decreases
Why does electronegativity increase down the group?
The halogens are highly electronegative
Larger atoms attract less than smaller ones
Their outer electrons are further from the nucleus and more shielded
Are halogens oxidising or reducing agents? Why?
Oxidising agents
They gain an electron
What happens to the oxidising power of the halogens as you move down the group?
They become less oxidising
What does “halide” describe?
The negative X- ion
What does the term “Halogen” refer to?
The atom X or the molecule X2
What colour is potassium chloride solution? (KCl)
Colourless
What is the reaction between potassium chloride solution and chlorine water?
No reaction
What colour is chlorine water (Cl2)?
Colourless
What colour is potassium bromide solution (KBr)?
Colourless
What is the reaction between potassium bromide solution and chlorine water?
Orange solution (Br2) formed
What colour is potassium iodide solution (KI)?
Colourless
What is the reaction between potassium iodide solution and chlorine water?
Brown solution (I2) formed
What is the colour of bromine water (Br2)?
Orange
What is the reaction between potassium chloride solution and bromine water?
No reaction
What is the reaction between potassium bromide solution and bromine water?
No reaction
What is the reaction of potassium iodide solution and bromine water?
Brown solution (I2) formed
What colour is iodide solution (I2)?
Brown
What is the reaction between the potassium chloride solution and iodine solution?
No reaction
What is the reaction between potassium bromide solution and iodide solution?
No reaction
What is the reaction between potassium iodide solution and iodine solution?
No reaction
What is the equation for the displacement reaction of chlorine and potassium iodide ions?
Cl2 + 2KI -> 2KCl +I2
What is the ionic equation for the displacement reaction of chlorine and potassium iodide ions?
Cl2 + 2I- -> 2Cl- + I2
What is the equation for the displacement reaction between chlorine and potassium bromide?
Cl2 + 2KBr -> 2KCl + Br2
What is the ionic equation for the displacement reaction between chlorine and potassium bromide?
Cl2 + 2Br- -> 2Cl- + Br2
What is the equation for the displacement reaction between bromine and potassium iodide?
Br2 + 2KI -> 2KBr + I2
What is the ionic equation for the displacement reaction between bromine and potassium iodide?
Br2 + 2I- -> 2Br- + I2
Why won’t iodine displace either Cl- or Br- halide?
It is below chlorine and bromine in group 7 so it is less reactive
What is formed when you mix chlorine gas with cold, dilute sodium hydroxide solution at room temperature?
Sodium chlorate (I) solution NaClO
What is a use of NaClO?
Household bleach
What is disproportionation?
In the reaction, chlorine being both oxidised and reduced
What is the equation for the formation of bleach?
2NaOH +Cl2 -> NaClO + NaCl + H2O
What is chlorine’s oxidation state in Cl2?
O
What is chlorine’s oxidation state in NaClO?
+1
What is chlorine’s oxidation state in NaCl?
-1
What happens when chlorine reacts with water?
Disproportionation
What is formed when chlorine reacts with water?
A mixture of chloride ions and chlorate (I) ions
What is the equation when chlorine reacts with water?
Cl2 + H2O 2H+ + Cl- + ClO-
What is chlorine’s oxidation state in Cl-?
-1
What is chlorine’s oxidation state in ClO-?
+1
Why is chlorine used in water treatment?
Chlorate ions kill bacteria
Why is chlorine an important part of water treatment?
It kills disease-causing microorganisms
Prevents reinfection further down the supply
Prevents the growth of algae, eliminating bad tastes and smells and removing discolouration caused by organic compounds
What are the risks of using chlorine in water treatment?
Chlorine is toxic
Harmful if chlorine gas is breathed in - irritates the respiratory system
Liquid chlorine causes chemical burns on the skin and eyes