What is the general equation for the reaction of a Group 2 metal (M) with oxygen?

2M (s) + O 2 (g) → 2MO (s) Note: Sr and Ba also form MO 2 in addition to MO.

All Group 2 metals react with water according to: M (s) + 2H 2 O (l) → .......... + .......... , except .......... which does not react with water.

All Group 2 metals react with water according to: M (s) + 2H 2 O (l) → M(OH) 2 (s) + H 2 (g) , except Be which does not react with water.

True or False? Barium sulfate (BaSO 4 ) and strontium sulfate (SrSO 4 ) are both insoluble in water.

True. Both BaSO 4 and SrSO 4 are insoluble, which means barium and strontium do not dissolve readily in dilute H 2 SO 4 , unlike magnesium and calcium.

Write the general equation for the reaction of a Group 2 metal (M) with dilute hydrochloric acid.

M (s) + 2HCl (aq) → MCl 2 (aq) + H 2 (g)

When excess sodium hydroxide is added to a solution of Mg 2+ ions, a .......... precipitate of .......... forms; with Ba 2+ ions, .......... is observed.

When excess sodium hydroxide is added to a solution of Mg 2+ ions, a white precipitate of Mg(OH) 2 forms; with Ba 2+ ions, no change is observed (Ba(OH) 2 is soluble).

True or False? All Group 2 metals form a white precipitate when excess sodium hydroxide solution is added.

False. Mg 2+ and Ca 2+ give white precipitates; Sr 2+ gives only a slight precipitate; Ba 2+ gives no visible change with NaOH because Ba(OH) 2 is soluble.

Which Group 2 ions give a white precipitate when reacted with ammonia solution, and which do not?

Only Mg 2+ gives a white precipitate (Mg(OH) 2 ) with ammonia solution. Ca 2+ , Sr 2+ and Ba 2+ show no change, because their hydroxides are too soluble to precipitate under these conditions.

A precipitate is an insoluble solid that forms when two solutions are mixed and a product is produced that is insoluble in the solvent, appearing as a solid within the solution.

What is the correct order of testing for anions in an unknown solution and why?

Test for carbonate first , then sulfate , then halide . Carbonate interferes with both barium chloride and silver nitrate tests; it must be removed first so that subsequent tests are unambiguous.

To test for sulfate ions, acidify the sample with dilute .......... and add aqueous .......... ; a .......... precipitate of .......... is a positive result.

To test for sulfate ions, acidify the sample with dilute HCl and add aqueous barium chloride ; a white precipitate of BaSO 4 is a positive result.

True or False? Silver chloride dissolves in concentrated ammonia, silver bromide dissolves in dilute ammonia, and silver iodide does not dissolve in ammonia at all.

False. Silver chloride dissolves in dilute ammonia; silver bromide dissolves in concentrated ammonia; silver iodide does not dissolve in ammonia.

What colour precipitate is formed when silver nitrate solution is added to a solution containing iodide ions (I - )?

A yellow precipitate of silver iodide (AgI) is formed.

To test for ammonium ions, add .......... solution and warm; hold damp red litmus paper over the mouth of the test tube. A positive result turns the paper .......... , indicating the presence of .......... gas.

To test for ammonium ions, add sodium hydroxide solution and warm; hold damp red litmus paper over the mouth of the test tube. A positive result turns the paper blue , indicating the presence of ammonia gas.

True or False? Dilute nitric acid is added before silver nitrate when testing for halide ions to prevent false positives from carbonate or hydroxide ions.

True. Carbonate and hydroxide ions also precipitate with silver nitrate (as Ag 2 CO 3 and AgOH). Acidifying with HNO 3 first removes these ions, preventing false positives.

What observation confirms the presence of carbonate ions (CO 3 2- ) in an unknown solution?

Adding dilute HCl produces bubbles of gas ; when this gas is bubbled through limewater (Ca(OH) 2 (aq)), the limewater turns milky , confirming the gas is CO 2 .

A carbonyl compound is an organic compound containing the carbonyl group (C=O). This includes aldehydes (–CHO), ketones (C=O within the chain), carboxylic acids (–COOH), esters (–COO–), and amides (–CONH–).

Why is an electric heating mantle used instead of a Bunsen burner when distilling an organic product?

The temperature can be controlled precisely and, more importantly, it eliminates an open flame, which is essential when working with flammable organic solvents and reactants.

In distillation apparatus, water enters the condenser at the .......... and exits at the .......... , ensuring efficient cooling of vapour rising from the flask.

In distillation apparatus, water enters the condenser at the bottom and exits at the top , ensuring efficient cooling of vapour rising from the flask.

True or False? The distillate should be collected across the full temperature range during distillation, not just at a specific temperature.

False. Only the fraction collected within ±2 °C of the boiling point of the desired product should be kept. Distillate collected below this range should be discarded using a separate vessel.

In the preparation of cyclohexene from cyclohexanol, what reagent is used to remove acidic impurities from the crude distillate?

Saturated sodium hydrogen carbonate solution, added in a separating funnel. It reacts with and removes traces of phosphoric acid and other acidic impurities.

After washing the crude organic product with sodium hydrogen carbonate solution, solid .......... is added to the organic layer to remove remaining .......... , before the final distillation.

After washing the crude organic product with sodium hydrogen carbonate solution, solid anhydrous calcium chloride is added to the organic layer to remove remaining water , before the final distillation.

True or False? An aldehyde can be produced from a primary alcohol by distilling the product off as soon as it forms, preventing further oxidation to a carboxylic acid.

True. The aldehyde has a lower boiling point than the alcohol (due to loss of H-bonding) so it can be distilled off immediately. If left in contact with the oxidising agent, it would be further oxidised to a carboxylic acid.

How can you confirm that the product collected from the distillation of cyclohexanol is an alkene?

Add a small portion to bromine water : a positive result is decolourisation from orange-brown to colourless , confirming the C=C double bond of cyclohexene.

A drying agent is an anhydrous solid added to an organic liquid to absorb traces of water . Anhydrous calcium chloride (CaCl 2 ) is commonly used after washing an organic product in a separating funnel.

What is Tollens' reagent and what is its other name?

An aqueous alkaline solution of silver nitrate in excess ammonia solution. It is also called ammoniacal silver nitrate solution .

True or False? Acidified potassium dichromate can be used to distinguish a primary alcohol from an aldehyde.

False. Both primary alcohols and aldehydes turn acidified potassium dichromate from orange to green. Use Tollens' reagent or Fehling's solution to distinguish between them.

When bromine water is shaken with an alkene, the orange-yellow solution .......... due to an .......... reaction with the double bond.

When bromine water is shaken with an alkene, the orange-yellow solution decolourises due to an addition reaction with the double bond.

What observation confirms a positive Fehling's solution test for an aldehyde?

The clear blue solution turns opaque and a red precipitate (copper(I) oxide, Cu 2 O) forms. A colour change alone without mentioning the precipitate is insufficient.

True or False? A tertiary alcohol turns acidified potassium dichromate from orange to green.

False. Tertiary alcohols cannot be oxidised, so the solution remains orange. Only primary and secondary alcohols cause the colour change to green.

When an aldehyde is warmed with Tollens' reagent, the Ag + ions are .......... to Ag atoms, forming a silver .......... on the inside of the test tube.

When an aldehyde is warmed with Tollens' reagent, the Ag + ions are reduced to Ag atoms, forming a silver mirror on the inside of the test tube.

True or False? When adding sodium carbonate solution to an unknown compound, effervescence confirms the presence of a carboxylic acid.

False. Effervescence alone only confirms that a gas is produced. The gas must also be bubbled through limewater. If it turns milky/cloudy, CO 2 is confirmed, proving a carboxylic acid is present.

A bidentate ligand is a ligand that donates two lone pairs of electrons to the central metal ion, forming two dative covalent bonds. Examples include ethane-1,2-diamine (en) and the ethanedioate ion (C 2 O 4 2- ).

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Organic & Inorganic Chemistry Practicals (AQA A Level Chemistry): Flashcards

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FrontReactions of Group 2 Elements
What is the general equation for the reaction of a Group 2 metal (M) with oxygen?

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What is the general equation for the reaction of a Group 2 metal (M) with oxygen?
2M (s) + O₂ (g) → 2MO (s)
Note: Sr and Ba also form MO₂ in addition to MO.
All Group 2 metals react with water according to: M (s) + 2H₂O (l) → .......... + .......... , except .......... which does not react with water.
All Group 2 metals react with water according to: M (s) + 2H₂O (l) → M(OH)₂ (s) + H₂ (g), except Be which does not react with water.
True or False?
Barium sulfate (BaSO₄) and strontium sulfate (SrSO₄) are both insoluble in water.
True.
Both BaSO₄ and SrSO₄ are insoluble, which means barium and strontium do not dissolve readily in dilute H₂SO₄, unlike magnesium and calcium.
Write the general equation for the reaction of a Group 2 metal (M) with dilute hydrochloric acid.
M (s) + 2HCl (aq) → MCl₂ (aq) + H₂ (g)
When excess sodium hydroxide is added to a solution of Mg²⁺ ions, a .......... precipitate of .......... forms; with Ba²⁺ ions, .......... is observed.
When excess sodium hydroxide is added to a solution of Mg²⁺ ions, a white precipitate of Mg(OH)₂ forms; with Ba²⁺ ions, no change is observed (Ba(OH)₂ is soluble).
True or False?
All Group 2 metals form a white precipitate when excess sodium hydroxide solution is added.
False.
Mg²⁺ and Ca²⁺ give white precipitates; Sr²⁺ gives only a slight precipitate; Ba²⁺ gives no visible change with NaOH because Ba(OH)₂ is soluble.
Which Group 2 ions give a white precipitate when reacted with ammonia solution, and which do not?
Only Mg²⁺ gives a white precipitate (Mg(OH)₂) with ammonia solution.
Ca²⁺, Sr²⁺ and Ba²⁺ show no change, because their hydroxides are too soluble to precipitate under these conditions.
Precipitate
A precipitate is an insoluble solid that forms when two solutions are mixed and a product is produced that is insoluble in the solvent, appearing as a solid within the solution.
What is the correct order of testing for anions in an unknown solution and why?
Test for carbonate first, then sulfate, then halide.
Carbonate interferes with both barium chloride and silver nitrate tests; it must be removed first so that subsequent tests are unambiguous.
To test for sulfate ions, acidify the sample with dilute .......... and add aqueous .......... ; a .......... precipitate of .......... is a positive result.
To test for sulfate ions, acidify the sample with dilute HCl and add aqueous barium chloride; a white precipitate of BaSO₄ is a positive result.
True or False?
Silver chloride dissolves in concentrated ammonia, silver bromide dissolves in dilute ammonia, and silver iodide does not dissolve in ammonia at all.
False.
Silver chloride dissolves in dilute ammonia; silver bromide dissolves in concentrated ammonia; silver iodide does not dissolve in ammonia.
What colour precipitate is formed when silver nitrate solution is added to a solution containing iodide ions (I^-)?
A yellow precipitate of silver iodide (AgI) is formed.
To test for ammonium ions, add .......... solution and warm; hold damp red litmus paper over the mouth of the test tube. A positive result turns the paper .......... , indicating the presence of .......... gas.
To test for ammonium ions, add sodium hydroxide solution and warm; hold damp red litmus paper over the mouth of the test tube. A positive result turns the paper blue, indicating the presence of ammonia gas.
True or False?
Dilute nitric acid is added before silver nitrate when testing for halide ions to prevent false positives from carbonate or hydroxide ions.
True.
Carbonate and hydroxide ions also precipitate with silver nitrate (as Ag₂CO₃ and AgOH). Acidifying with HNO₃ first removes these ions, preventing false positives.
What observation confirms the presence of carbonate ions (CO₃^2-) in an unknown solution?
Adding dilute HCl produces bubbles of gas; when this gas is bubbled through limewater (Ca(OH)₂(aq)), the limewater turns milky, confirming the gas is CO₂.
Qualitative analysis
A carbonyl compound is an organic compound containing the carbonyl group (C=O). This includes aldehydes (–CHO), ketones (C=O within the chain), carboxylic acids (–COOH), esters (–COO–), and amides (–CONH–).
Why is an electric heating mantle used instead of a Bunsen burner when distilling an organic product?
The temperature can be controlled precisely and, more importantly, it eliminates an open flame, which is essential when working with flammable organic solvents and reactants.
In distillation apparatus, water enters the condenser at the .......... and exits at the .......... , ensuring efficient cooling of vapour rising from the flask.
In distillation apparatus, water enters the condenser at the bottom and exits at the top, ensuring efficient cooling of vapour rising from the flask.
True or False?
The distillate should be collected across the full temperature range during distillation, not just at a specific temperature.
False.
Only the fraction collected within ±2 °C of the boiling point of the desired product should be kept. Distillate collected below this range should be discarded using a separate vessel.
In the preparation of cyclohexene from cyclohexanol, what reagent is used to remove acidic impurities from the crude distillate?
Saturated sodium hydrogen carbonate solution, added in a separating funnel. It reacts with and removes traces of phosphoric acid and other acidic impurities.
After washing the crude organic product with sodium hydrogen carbonate solution, solid .......... is added to the organic layer to remove remaining .......... , before the final distillation.
After washing the crude organic product with sodium hydrogen carbonate solution, solid anhydrous calcium chloride is added to the organic layer to remove remaining water, before the final distillation.
True or False?
An aldehyde can be produced from a primary alcohol by distilling the product off as soon as it forms, preventing further oxidation to a carboxylic acid.
True.
The aldehyde has a lower boiling point than the alcohol (due to loss of H-bonding) so it can be distilled off immediately. If left in contact with the oxidising agent, it would be further oxidised to a carboxylic acid.
How can you confirm that the product collected from the distillation of cyclohexanol is an alkene?
Add a small portion to bromine water: a positive result is decolourisation from orange-brown to colourless, confirming the C=C double bond of cyclohexene.
Drying agent
A drying agent is an anhydrous solid added to an organic liquid to absorb traces of water. Anhydrous calcium chloride (CaCl₂) is commonly used after washing an organic product in a separating funnel.
What is Tollens' reagent and what is its other name?
An aqueous alkaline solution of silver nitrate in excess ammonia solution. It is also called ammoniacal silver nitrate solution.
True or False?
Acidified potassium dichromate can be used to distinguish a primary alcohol from an aldehyde.
False.
Both primary alcohols and aldehydes turn acidified potassium dichromate from orange to green. Use Tollens' reagent or Fehling's solution to distinguish between them.
When bromine water is shaken with an alkene, the orange-yellow solution .......... due to an .......... reaction with the double bond.
When bromine water is shaken with an alkene, the orange-yellow solution decolourises due to an addition reaction with the double bond.
What observation confirms a positive Fehling's solution test for an aldehyde?
The clear blue solution turns opaque and a red precipitate (copper(I) oxide, Cu₂O) forms. A colour change alone without mentioning the precipitate is insufficient.
True or False?
A tertiary alcohol turns acidified potassium dichromate from orange to green.
False.
Tertiary alcohols cannot be oxidised, so the solution remains orange. Only primary and secondary alcohols cause the colour change to green.
When an aldehyde is warmed with Tollens' reagent, the Ag⁺ ions are .......... to Ag atoms, forming a silver .......... on the inside of the test tube.
When an aldehyde is warmed with Tollens' reagent, the Ag⁺ ions are reduced to Ag atoms, forming a silver mirror on the inside of the test tube.
True or False?
When adding sodium carbonate solution to an unknown compound, effervescence confirms the presence of a carboxylic acid.
False.
Effervescence alone only confirms that a gas is produced.
The gas must also be bubbled through limewater. If it turns milky/cloudy, CO₂ is confirmed, proving a carboxylic acid is present.
Fehling's solution
A bidentate ligand is a ligand that donates two lone pairs of electrons to the central metal ion, forming two dative covalent bonds. Examples include ethane-1,2-diamine (en) and the ethanedioate ion (C₂O₄^2-).

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