Unit 2 - Section 2 Flashcards
What is the reactivity of water down group 2?
The reactivity with water increases down group 2 as the elements get oxidised and the first ionisation energy is lower down group 2
What is the solubility of group 2 elements in -1 solutions?
It starts out less soluble and then becomes more soluble further down
What is the solubility of group 2 elements in -2 solutions?
It starts out most soluble and then the solubility falls as you go down group 2
What is the test for sulfate ions?
Add dilute hydrochloric acid and then barium chloride solution, if a white precipitate is formed then it contains sulfate ions
What is a barium meal and what is it used for?
Barium sulfate is swallowed and then it will show up on X-rays so you can see soft tissue
How is titanium purified and what is the equation for this?
First the ore (TiCl4) is heated with carbon in a steam of chlorine gas, it is purified by fractional distillation, and then is reduced by magnesium in a finance at 1000 degrees
TiCl4(g) + 2Mg (l) -> Ti(s) + 2MgCl2(l)
How are sulfur dioxide removed from four gases?
A slurry is made by mixing limestone (CaCO3) with water, this slurry is sprayed onto the flue gases. The alkaline slurry reacts with the sulfure dioxide to produce a solid waste product, calcium sulfite
CaCO3(s) + 2H2O(l) + SO2(g) -> CaSO3(s) + 2H2O(l) + CO2(g)
What are the properties of halogens?
Boiling point - the boiling points increase down group 2, this is because van der Walls increase
Electronegative - decreases down the group as here is more shielding
How do you find out what halogens are in a solution?
Halogens become less reactive down group 7, this means if you have KI it will react with every halogen before it and will turn the colour of the element
How is bleached made?
Chlorine gas is mixed with cold, dilute sodium hydroxide solution. This forms a sodium chlorite solution (NaClO) also known as bleach
2NaOH(aq) + Cl2(g) -> NaClO(aq) + NaCl(aq) + H2O(l)
This is called disproportionation
What are the two ways to form chlorine ions?
Add water to Chlorine
Cl2(g) + H2O(l) 2H^+(aq) + Cl^-(aq) + ClO^-(aq)
Or
In sunlight, chlorine can decompose water
Cl2(g) + H2O(l) 2H^+(aq) + 2Cl^-(aq) + 1/2O2(g)
How to remember oxidation and reduction
OIL RIG
Oxidation is loosing electrons
Reduction is gaining electrons
What are halides ions?
They are formed by the halogens being oxidised (-1 charge)
How do you test for halides?
Using the silver nitrate test.
Add dilute nitric acid to take out any other ions. Then add a few drops of silver nitrate solution (AgNO3). A precipitate is formed
What colour precipitate is formed from the silver nitrate test?
Fluoride - no precipitate
Chloride - white precipitate
Bromide - cream precipitate
Iodide - yellow precipitate
