Group 7-halogens Flashcards
what happens to the boiling point of halogens
decrease down the group, vvw forces increases in strength, lower the bp the more volatile the element
what is the trend in electronegativity
decreases down the group , larger atoms attract electrons less than smaller ones, outer electrons further away from nucleus
what is the trend in oxidising ability?
increases going up the group
how are halogens involved in displacement reations
they become oxidising agents ,and a halogen will displace a halide from the solution
what element has the highest reducing ability
i-
why is chlorine used in water treatment
prevents life threatening diseases by killing bacteria by oxidation
how does chlorine react with alkali
reacts with cold dilute sodium hydroxide to form sodium chlorate-forms bleach
What is the formula for Chlorine (CL) reacting with potassium bromide solution
Cl2+2kBr–>2KCl(aq)+Br2(aq)
What are halides and names
Halides are the 1- ions formed by halogens and end in ide
What is the reaction between sodium hydroxide and chlorine(bleach)
2naoh+Cl2–>NaClO+NaCl+H20
What is the formula for chlorine and water
cl2+h20=HClO+HCl
How do u test for halides using silver nitrate test
- Add dilute nitric acid remove ions
- add silver nitrate=precipitate
- add amonnia distinguish halides
How do u test for positive ions in flame test
Dip wire in hcl to clean it and then dip it in unknown compound ,hold the loop in. The blue flame and observe the colour change
How do you test for ammonium ions
Damp litmus paper so ammonia gas can dissolve ,if present the paper will turn blue, adding hydroxide ions cause ammonia to react to form NH+h20
How do you test for hydroxide ions
Add a PH indicator
How do you test for halide ions
Add dilute nitric acid followed by silver nitrate and then add ammonia solution to tell them apart ,silver chlride will dissolve in dilute ammonia solution silver bromide will only dissolve in concentrated ,iodide won’t at all
Test for carbonate ions
Adding an acid and it should fiz and test for carbon dioxide using like water and should go cloudy
how do halides react with sulfuric acid
NaX+h2so4->nahso4+HX
forms a hydrogen halide
How do you test for sulphate ions
using barium chloride. If barium chloride solution is added to a sample of water containing sulfate ions, barium sulfate is formed. Barium sulfate is insoluble in water, and will be seen as a white precipitate.
