Exp. 7: Water: Its properties and purification

ChemLab

Water

Water

_______ is one of the most abundant compound on Earth. It is essential in all living organisms and necessary to sustain life. Its chemical components that consists of 2 hyrdogen atoms and an oxygen atom covalently bonded together. Its unique physical properties, it can exists in three state of matter.

high polarity characteristics

Water is known to be a universal solvent due to its ________ characteristics as a molecule.

Hydrate

A compound containing  water molecules

Anhydrous compound

a compound does not contain water molecules.​

Efflorescence

property of a crystal releases water when exposed to atmosphere with low vapor pressure, it becomes anhydrous.​ ex. Gauleber's salt (Na 2SO 4 ● 10 H 2O (s)

No reaction

Gauleber's salt (Na 2SO 4 ● 10 H 2O (s) ) on watch glass for 5 mins. Reaction?

Deliquescence

property of a crystal that absorbs water from the atmosphere with high vapor pressure, it becomes hydrated. ​ex. CaCl2

Dissolved (liquid state)

Anhydrous calcium chloride (CaCl2), white powder, on watch glass for 5 mins. Reaction?

Light blue to White

Heated blue vitriol CuSO 4 ● 5 H 2O (s) + heat -> CuSO 4 (s) + 5 H 2O (g) Reaction?

white crystal to light blue

Anhydrous copper (II) sulfate CuSO 4 (s) + 5 H 2O (l) -> CuSO 4 ● 5 H 2O (s)Reaction?

solvent and dilution

Uses of water

solute

_______ is the one that dissolves

solvent

______ is the one that does the dissolving

dilution

resulting for a less concentrated solution​

precipitate

a reaction between two solutions forming a solid substance

No reaction

Mixed barium chloride (BaCl2) (white) and potassium chromate (K2CrO4) (egg yellow) on a dry test tube. Reaction?

dissolves in water

Mixed barium chloride (BaCl2) and potassium chromate (K2CrO4) + water. Reaction?

egg yellow precipitate

Mixed barium chloride (BaCl2) and potassium chromate (K2CrO4) on a dry test tube added with water after 5-10 mins.

BaCl2(aq) + K2CrO4(aq)  BaCrO4(s) --> 2 KCl(aq) Reaction?

blue green solution, brown gas

Copper wire with 1 mL concentrated Nitric acid (HNO3).

4 HNO3(l) +Cu(s) -> Cu(NO3)2(aq) + 2 NO2(g) + 2 H2O(l)

Reaction?

blue solution, yellow gas

Copper wire with 1 ml Nitric acid (HNO3) + 2 mL water.

8 HNO3(aq) +3 Cu(s) -> Cu(NO3)2(aq) + 2 NO(g) + 4 H2O(l)

Reaction?

Hydrolysis

a chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water

Yellow, clear liquid

Water + ferric chloride. Reaction?

Brown acidic solution

Water + ferric chloride + heat (5mins). Reaction?

Surface Tension

the tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area.

Diffusion

is the movement of a fluid from an area of higher concentration to an area of lower concentration.

Turbidity

is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.

Alum solution

___________ is used as coagulants or flocculants  (forming large particles). It causes them to clump together so that they can settle out of the water or be easily trapped by a filter. ​

red

blue litmus paper turns _____ in an acidic solution

blue

red litmus paper turns _____ in an basic solution

Distillation

is a process of purifying a substance; or a miscible liquid with different boiling temperature; or soluble mixture.

Thermometer

Name that thing (No. 1)

Distilling Flask

Name that thing (No. 2)

Bunsen burner

Name that thing (No. 3)

Condenser

Name that thing (No. 4)

adapter

Name that thing (No. 5)

Erlenmeyer flask

Name that thing (No. 6)

Distillated water

Name that thing (No. 7)

carbonate, bicarbonates, chlorides and sulfates

Hardness in water is due to the present of mineral salts of _______, ______, ________, and __________ of Ca 2+, Mg 2+,Fe +3

Least

Distilled water (standard soap sol, detergent sol, observation)

More

Tap water (standard soap sol, detergent sol, observation)

moderate

Boiled Water (standard soap sol, detergent sol, observation)

Temporary and permanent

Types of Hardness of Water

Temporary hardness

due to the presence of bicarbonate , HCO 3 – 1 & carbonate, CO 3 – 2 of Ca 2+, Mg 2+, Fe +3 like calcium carbonate, magnesium carbonate and ferric carbonate can be removed by boiling or distillation.

Permanent hardness

due to the presence of chlorides, Cl – 1 and sulfates, SO 4 – 2 of Ca 2+, Mg 2+, Fe +3 and can be removed by cation and anion exchange.

Soft water

treated water, absence of minerals and removal of permanent hardness