Water Part2 Flashcards
What comprises all the water bodies present on the Earth’s surface?
Surface water
Includes lakes, rivers, oceans, and seas.
What are the sources of rivers?
Glaciers, snow, and rainfall
These sources contribute to the flow of rivers.
What is the process of removing salt from seawater called?
Desalination
This process makes seawater suitable for drinking.
What is groundwater?
Water that collects underground after rainwater percolates through rocky layers
It can be accessed through wells and tube wells.
What are springs?
Natural fountains where groundwater spontaneously comes out
Hot springs are a specific type of spring with heated water.
What happens to groundwater during summer?
It supplements the demand for water
Groundwater is crucial during dry seasons.
What is dissolution?
The process involving the disappearance of a solid in water
The resulting mixture is called a solution.
What is a sugar solution?
The product formed when sugar dissolves in water
This process is called dissolution.
What type of change is the dissolution of sugar in water?
Physical change
No new substance is formed, and the properties remain unchanged.
What is the dissolution of salt in water classified as?
Chemical process
It breaks down into sodium and chloride ions.
What happens to salt when it dissolves in water?
It breaks down into sodium and chloride ions
This process involves the attraction of water molecules to the ions.
What is the equation representing the dissolution of sodium chloride?
NaCl(s) → Na+(aq) + Cl-(aq)
This illustrates the ionic dissociation in water.
True or False: Dissolving a covalent compound like sugar results in a chemical reaction.
False
The chemical identity of sugar remains unchanged.
Fill in the blank: The process of a solid disappearing in water is called _______.
Dissolution
What is a solute?
A solid that dissolves in a liquid.
What is a solvent?
The liquid in which the solid dissolves.
What is a solution?
A mixture formed when a solid dissolves in a liquid.
What does ‘aqueous solution’ mean?
A solution where a substance dissolves in water.
What is an example of a solute and solvent?
Common salt is the solute and water is the solvent, resulting in a salt solution.
Why is water called a universal solvent?
Because it dissolves almost all substances on earth.
What can water dissolve?
Most minerals, nutrients, salts, metals, and gases like oxygen and carbon dioxide.
What is solubility?
The ability of a solute to dissolve in a given solvent at a given temperature.
How is solubility usually expressed?
As a percentage.
What is the solubility of a solid?
The amount of solute which 100 grams of a solvent can dissolve at a given temperature.
What is a saturated solution?
A solution in which no more solute can dissolve at a specific temperature.
What is an unsaturated solution?
A solution in which more solute can dissolve at a specific temperature.
What is a supersaturated solution?
A solution that contains more solute than the solvent can dissolve at a specific temperature.
How does temperature affect solubility?
Solubility increases with temperature; a saturated solution becomes unsaturated on heating.
How does stirring affect the formation of a solution?
Stirring increases the rate of formation of a solution.
How does particle size affect solubility?
Smaller particle size leads to faster dissolution.
What is an example of a colloid?
Starch solution, gum, blood, ink, and clouds behave like colloids.
Why does the sky appear blue when looking through a cloud?
The sky appears blue due to the scattering of light by colloidal particles.
How can colloids be identified?
Colloids can be identified by the Tyndall effect.
What is a true solution?
A true solution is a homogeneous mixture where the solute has a particle size of less than 1 nm.
What is an example of a true solution?
A simple solution of sugar in water is an example of a true solution.
Can particles of a true solution be filtered?
Particles of a true solution cannot be filtered through filter paper.
What is a suspension?
A suspension is a heterogeneous mixture where solute particles remain visible and can be removed by filtration.
What is the Tyndall effect?
The Tyndall effect is the scattering of light by colloidal particles, making the path of light visible in a colloid.
How do colloids differ from suspensions and true solutions?
Colloids have particle sizes smaller than those in suspensions but larger than those in true solutions.
What happens to light when passed through a true solution?
When light is passed through a true solution, its path is not illuminated.
What is the appearance of colloids?
Colloids are translucent, and their particles are partially visible.
What is the Tyndall effect?
Light scattering by colloidal particles is called the Tyndall effect.
What is an example of a true solution?
A starch solution is an example of a true solution.
What is water of crystallisation?
Water of crystallisation is the fixed amount of water necessary for certain salts to crystallise out from their aqueous solutions.
What role does water of crystallisation play in crystal formation?
It makes it possible for salts to form crystals and is responsible for the shapes of their crystals.
What do crystals contain?
Crystals contain salts and water combined in definite proportions.
What happens to crystals when heated?
When heated, the water is lost, and the crystals may form a white powder.
Give an example of a salt that crystallises with water.
CuSO₄·5H₂O (blue crystals) is an example, formed by the combination of 1 mole of CuSO₄ with 5 molecules of H₂O.
When heated, it loses the water of crystallisation (i.e., 5 molecules) and forms a white powder, CuSO₄.
What is the chemical formula for hydrated salts?
Hydrated salts contain water of crystallisation, such as Na₂CO₃·10H₂O, Na₂SO₄·10H₂O, and FeSO₄·7H₂O.
What happens to hydrated salts when heated?
When heated, hydrated salts lose their water of crystallisation and become anhydrous salts.
What are efflorescent substances?
Efflorescent substances lose their water of crystallisation when exposed to air.
What is lattice water?
Lattice water occupies certain positions in the crystal structure and is not attached by chemical bonds.
Give an example of a hydrate with lattice water.
KAl(SO₄)₂·12H₂O has 6H₂O molecules as lattice water and 6 as water of crystallisation.
What is the phenomenon called when a substance loses water of crystallisation?
The phenomenon is called efflorescence.
What is hygroscopic substance?
Hygroscopic substances absorb moisture from the atmosphere but do not form solutions.
What is the phenomenon called when substances absorb moisture from the atmosphere?
The phenomenon is called hygroscopy.
What are drying agents?
Substances used to remove moisture from other substances without chemically reacting with them.
Example: Concentrated sulphuric acid (H2SO4), quicklime (CaO), silica gel, etc.
What is deliquescence?
The phenomenon where substances absorb water from the atmosphere and become moist, ultimately turning into solutions.
Example: Caustic soda (NaOH), crystalline magnesium chloride (MgCl2), calcium chloride (CaCl2), etc.
Which common substance turns moist and forms a solution when exposed to air?
Table salt (NaCl) can turn moist and form a solution due to impurities like magnesium chloride and calcium chloride.
Sodium chloride itself is not deliquescent.
How do metals react with cold water?
Some metals like sodium (Na), potassium (K), and calcium (Ca) react vigorously with cold water to form hydroxides and liberate hydrogen gas.
How do metals like magnesium (Mg), zinc (Zn), and aluminum (Al) react with water?
They react with hot water to form oxides, hydroxides, and hydrogen gas.
What happens when iron (Fe) reacts with steam?
Iron reacts with steam to form iron(III) oxide (Fe2O3) and hydrogen gas (H2).
Which metals do not react with water?
Metals like copper (Cu), silver (Ag), gold (Au), mercury (Hg), lead (Pb), and platinum (Pt) do not react with water because they are less reactive than hydrogen.
What are drying agents?
Substances used to remove moisture from other substances without chemically reacting with them.
Example: Concentrated sulphuric acid (H2SO4), quicklime (CaO), silica gel, etc.
What is deliquescence?
The phenomenon where substances absorb water from the atmosphere and become moist, ultimately turning into solutions.
Example: Caustic soda (NaOH), crystalline magnesium chloride (MgCl2), calcium chloride (CaCl2), etc.
Which common substance turns moist and forms a solution when exposed to air?
Table salt (NaCl) can turn moist and form a solution due to impurities like magnesium chloride and calcium chloride.
Sodium chloride itself is not deliquescent.
How do metals react with cold water?
Some metals like sodium (Na), potassium (K), and calcium (Ca) react vigorously with cold water to form hydroxides and liberate hydrogen gas.
How do metals like magnesium (Mg), zinc (Zn), and aluminum (Al) react with water?
They react with hot water to form oxides, hydroxides, and hydrogen gas.
What happens when iron (Fe) reacts with steam?
Iron reacts with steam to form iron(III) oxide (Fe2O3) and hydrogen gas (H2).
Which metals do not react with water?
Metals like copper (Cu), silver (Ag), gold (Au), mercury (Hg), lead (Pb), and platinum (Pt) do not react with water because they are less reactive than hydrogen.
What is hard water?
Hard water does not easily form lather with soap.
What is soft water?
Soft water easily forms lather with soap.
What causes water to be hard?
Water is said to be hard when it contains calcium and magnesium in large amounts.
Where is hard water commonly found?
Groundwater contains more salts that contribute to hardness.
What are the differences between hard water and soft water?
The differences between hard water and soft water are given in Table 8.3.
What metals react with steam?
Metals such as aluminium, zinc, and iron react vigorously with steam to form oxides of metal and hydrogen gas.
What does magnesium metal react with?
Magnesium metal reacts with hot water to form magnesium hydroxide.
What is hard water?
Hard water does not easily form lather with soap.
What is soft water?
Soft water easily forms lather with soap.
What causes water to be hard?
Water is said to be hard when it contains calcium and magnesium in large amounts.
Where is hard water commonly found?
Groundwater contains more salts that contribute to hardness.
What are the differences between hard water and soft water?
The differences between hard water and soft water are given in Table 8.3.
What metals react with steam?
Metals such as aluminium, zinc, and iron react vigorously with steam to form oxides of metal and hydrogen gas.
What does magnesium metal react with?
Magnesium metal reacts with hot water to form magnesium hydroxide.
