NAME: JAIME VIEIRA RUIZ (F19015Z)

SAMPLE: Magnesium subcarbonate

BEHAVIOUR OF COMPOUND DURING HEATING AND BURNING (describe what you should see during the heating
of your sample in burner and choose one of possibility):

- No changes
- Melting to colourless liquid, which acquires the original colour after cooling down
- Change of the colour
- Releasing vapours
- Sublimation

                           ORGANIC/INORGANIC/ORGANIC-INORGANIC COMPOUND

ELEMENTARY ANALYSIS (write down the reactions of tests you should do and mark which of them should
be positive):

Inorganic compound

SOLUBILITY (decide according to the information in Ph. Eur.):

Practically insoluble in water. It dissolves in dilute acids with effervescence

pH of solution/suspension (decide according to nature of your sample):

Basic

REACTIONS FROM THE FLOWCHARTS (write down your “flowcharts pathway”; describe results of your
hypothetical analysis – reactions from the flowcharts you can find in material called
“Identification of an unknown drug”):

Unknown compound à Inorganic compound à solubility in water à no à solubility in HCl à Yes �
reaction with ammonium oxalate solution II à NEGATIVE à reaction with titanium yellow II à POSITIVE
à Magnesium subcarbonate or magnesium peroxide

IDENTIFICATION REACTIONS (from your monography choose the tests necessary for identification of
your substance and describe them):

B) Introduce into a test-tube 0.1 g of the substance to be examined and suspend in 2 mL of water R
or use 2 mL of the prescribed solution. Add 3 mL of dilute acetic acid R. Close the tube
immediately using a stopper fitted with a glass tube bent twice at right angles. The solution or
the suspension becomes effervescent and gives off a colourless and odourless gas. Heat gently and
collect the gas in 5 mL of barium hydroxide solution R. A white precipitate is formed that
dissolves on addition of an excess of hydrochloric acid R1.
1) CaCO[3 ]+ 2CH[3]COOH à Ca(CH[3]COO)[2] + CO[2] (Effervescent + odourless + colourless) + H[2]O
2) CO[2] + Ba(OH)[2] à BaCO[3] + H2O (White precipitate)
3) BaCO[3] + 2HCl à BaCl[2] + H[2]PO[3] (Dissolves the precipitate)

C) Dissolve about 15 mg in 2 mL of dilute nitric acid R and neutralise with dilute sodium hydroxide
solution R. The solution gives the reaction of magnesium.
MgCO[3] + HNO[3 ]--> Mg(NO[3])[2] + CO[2] + H[2]O
Mg(NO[3])[2] + NaOH --> Mg(OH)[2] + 2NaNO[3]

MAGNESIUM: Dissolve about 15 mg of the substance to be examined in 2 mL of water R or use 2 mL of
the prescribed solution. Add 1 mL of dilute ammonia R1. A white precipitate is formed that
dissolves on addition of 1 mL of ammonium chloride solution R. Add  1 mL of disodium hydrogen
phosphate solution R. A white crystalline precipitate is formed.

1) Mg^2+ + 2OH^- à Mg(OH)[2 ](white precipitate) + NH[4]Cl à dissolves
2) Mg^2+ + NH4^+ + HPO[4]^2- à NH[4]MgPO[4] + H^+ (White crystalline precipitate is formed)