A3 inorganics Flashcards
How do all electronic configurations of Group 2 elements end?
S (^2)
What happens to all group 2 elements in redox reactions?
Oxidised to form 2+ ions
General symbol equation for Group 2 elements reacting with dilute acid
General symbol equation for Group 2 elements reacting with water
Q
General symbol equation for Group 2 elements reacting with oxygen
State and explain the reactivity of Group 2 elements.
Reactivity increases down group
More shells
More shielding
Nuclear attraction decreases
Ionisation energy decreases
Less energy required to remove outer-shell electron
Down Group 2, what happens to elements’ reducing power?
Strong reducing agents
State how solubility changes down the group and the effect this has on the solution produced.
Solubility increases
More alkaline solutions form
Solutions have higher pH
General symbol equation for metal oxide reacting with water
What property of group 2 compounds makes them useful?
They are basic
What is the use of calcium hydroxide in commerce, and what is the equation?
Neutralise soil acids in agriculture
What is the use of magnesium hydroxide and calcium carbonate in commerce, and what are their equations?
Antacids to treat indigestion
What electronic configurations do all group 7 elements end with?
s(^2)p(^5)
What happens to all group 7 elements in redox reactions?
Reduced to form 1- ions
How do all group 7 elements exist?
Diatomic molecules
Why does the boiling point of group 7 elements decrease down the group?
London forces become stronger
More energy needed to break London forces
State and explain the trend in reactivity down group 7.
Reactivity decreases
More shells
Atomic radius increases
More shielding
Nuclear attraction decreases
Ionisation energy decreases
More energy required to attract outer-shell electron
Colour of chlorine regular? (room temp)
pale green gas
Colour of chlorine aqueous? in water
pale green
Colour of chlorine organic?
pale green
Colour of bromine regular?
Red-Brown liquid
Colour of bromine aqueous? water
Orange
Colour of bromine organic?
orange
Colour of iodine regular?
shiny grey black solid
Colour of iodine aqueous?
brown
Colour of iodine organic?
Violet
What is the state of astatine (At₂) at room temperature?
Predicted to be a solid, but never observed.
Why is cyclohexane used to identify halogens?
Halogens dissolve better in non-polar solvents, making their colours more distinct
Which halogen is the most reactive?
Fluorine (F₂).
Which halogen is the least reactive?
Iodine (I₂).
What is the state of fluorine (F₂) at room temperature?
Pale yellow gas.
Define Disproportionation.
The reduction and oxidation of the same element in the same redox reaction
Equation for chlorine reacting with cold, dilute aqeous sodium hydroxide, to form bleach
Chemical formula and name for bleach?
NaClO
Sodium Chlorate (I)
When chlorine is used to form bleach, what are the conditions required for sodium hydroxide?
Cold
Dilute
Equation for chlorine used for water treatment
Formula and name of acid created when chlorine is used for water treatment (not HCl)?
Chloric (I) acid
HClO
Benefits of using chlorine for sterilising drinking water?
Kills bacteria
Risks with using chlorine for sterilising drinking water?
Chlorine gas is toxic
Chlorinated hydrocarbons formed which are carcinogenic
How to test for halide ions and result?
Add HNO3
Add AgNO3
Add ammonia
Chloride white ppt dissolved in dilute ammonia (used to identify which one)
Bromide ppt dissolved in concentrated ammonia
Iodide ppt insoluble in concentrated ammonia
Equation for halide ion test
How to test for carbonate ions, and result?
Add HCl
Bubble gas through limewater
Limewater turns cloudy
Equation for carbonate ion test
How to test for sulfate ions?
Add HCl to remove any carbonates
Add BaCl2
White ppt will form
Equation for sulfate ion test
How to test for ammonium ions and result?
Add NaOH
Gently heat
Ammonia gas produced
Turns damp litmus blue
Equation for ammonium ion test
flame test method +ve ions
nicromere wire clean
dip in conc HCl
dip in sample
put into non- luminous bunion burner
Group 1 flame test results
Li - red
Na - yellow
K - lilac
group 2 flame test results
Mg - no colour
ca - orange-red
sr - red
Ba - green
What is the method to test for ammonium ions?
Add NaOH to the sample, heat, and place damp red litmus paper on the mouth of the test tube.
What indicates a positive result for the test for ammonium ions?
Indicator paper turns blue.
What is the order of the test for anions?
- Carbonate 2. Sulphate 3. Halide
What acronym helps remember the order of the test for anions?
CaSH.
What is the method to test for carbonate ions?
Add nitric acid to the sample, observe effervescence, and test the gas produced.
How do you test for the identity of the gas produced in the carbonate test?
Bubble it through limewater.
What indicates a positive result for the test for carbonate ions?
Limewater turns cloudy.
What is the method to test for sulphate ions?
Add nitric acid and then add barium chloride.
Why do you add nitric acid in the test for sulphate ions?
To remove any carbonate ions.
What is the positive result of the test for sulphate ions?
White precipitate.
What is the method to test for halide ions?
Add nitric acid and then add silver nitrate.
What is the positive result if there are chloride ions present in the test for halide ions?
White precipitate.
What is the positive result if there are bromine ions present in the test for halide ions?
cream precipitate.
What is the positive result if there are iodide ions present in the test for halide ions?
Yellow precipitate.
cl2 test and equation
damp blue litmus - white
cl2 + h20–> ccl + hclo
hydrogen test
burning split
- squeaky pop
oxygen test
glowing splint
- relights
when heated with NA0H - 1- iod is hydrolysed faster than 1- chloro why?>
c- I bond requires less energy to break than c- cl bond
one benefit and risk of cl in water treatment
benefit - harmful bacteria killed
risk - toxic - forms chlorinated hydrcarbosn
regagent for ppt test between halides
Agno3
how would the apperance of the Ppt allow you to distinguish between cl br and I ions
Cl - white Ppt
Br- cream ppt
I - yellow ppt
Explain the trend of halogens
down - icnewase Bp
increase Lf
increased strength
more energy
number of electrons increases
What happens when chlorine is added to bromide solution?
Chlorine displaces bromide, forming Br₂ (orange solution).
Reaction: Cl₂(aq) + 2Br⁻(aq) → 2Cl⁻(aq) + Br₂(aq)
What happens when chlorine is added to iodide solution?
Chlorine displaces iodide, forming I₂ (violet solution).
Reaction: Cl₂(aq) + 2I⁻(aq) → 2Cl⁻(aq) + I₂(aq)
What happens when bromine is added to iodide solution
Bromine displaces iodide, forming I₂ (violet solution).
Reaction: Br₂(aq) + 2I⁻(aq) → 2Br⁻(aq) + I₂(aq)
What happens when iodine is added to a halide solution?
No reaction, because iodine is the least reactive halogen.
How can you tell if a displacement reaction has occurred?
A colour change in solution indicates the formation of a new halogen.
what is the organic
cyclohexane
why is the 2nd ionisation energy important when explaining group 2 reactivity
group 2 elements react by losing 2 electrons to form 2+ ions
Heartburn is a form of indigestion caused by an excess of stomach acid.
State a compound of magnesium that could be used to treat heartburn. (1 mark)
magnesium carbonate, hydroxide or oxide
In an experiment, a student makes a solution of strontium chloride, SrCl₂, by adding excess dilute hydrochloric acid to strontium carbonate.
(i) Describe what the student would observe and write the equation for the reaction. (2 marks)
fizzing and solid dissolves
In another experiment, a student attempts to make a solution of strontium chloride by adding chlorine water to aqueous strontium bromide.
(i) Describe what the student would observe. (1 mark)
(ii) Write the ionic equation for the reaction which takes place. (1 mark)
solution turns orange
Chlorine is more reactive than bromine. Explain why. (4 marks)
cl gains an electron more easily than br
AN atom of cl is smaller than br
cl atoms there are fewer shells, less shielding
CL nuclear attraction on an electron to be gained in greater than br
b) A student was provided with an aqueous solution of calcium iodide. The student carried out a chemical test to show that the solution contained iodide ions. In this test, a precipitation reaction took place.
i) State the reagent that the student would need to add to the solution of calcium iodide. (1 mark)
ii) What observation would show that the solution contained iodide ions? (1 mark)
c) Write an ionic equation, including state symbols, for the reaction that took place. (1 mark)
d) The student is provided with an aqueous solution of calcium bromide that is contaminated with calcium iodide. The student carries out the same chemical test but this time needs to add a second reagent to show that iodide ions are present.
State the second reagent that the student should add. (1 mark)
i) Reagent: Silver nitrate solution (AgNO₃). (1)
ii) Observation: Yellow precipitate forms. (1)
Ag⁺(aq) + I⁻(aq) → AgI(s)
Concentrated ammonia solution (NH₃).
Silver iodide does not dissolve in ammonia, whereas silver bromide does.
ii. A student adds a small volume of aqueous silver nitrate to an aqueous solution of bromide ions in a test-tube. The student then adds a similar volume of dilute aqueous ammonia to the same test-tube.
Describe what the student would see in the test-tube after the addition of aqueous ammonia.
cream PPT
adding sodium carbonate
effervescences
calcium carbonate to calcium oxide type of reaction
thermal decomposition
a student prepared some calcium hydroxide by addition a small piece of calcium to large excess of water that is the observation
effervescence and solid disaapears
