Is Matter Around Us Pure? Flashcards
What is a pure substance?
A pure substance consists of a single type of particle which means that all the constituent particles of that substance are the the same in their chemical nature.
What are Mixtures?
Two or more than two different substances (element or compound) put together in no fixed
proportion.
What are Homogeneous Mixtures? Give an example.
Mixtures in which the components mix with each other uniformly. Eg Salt in water, Sugar in water
What are Heterogenous Mixtures?
Mixtures in which the composition of a mixture is non-uniform. Eg Oil in water, Sand in water
What is a solution? What are its properties?
It is a homogeneous mixture of two or more substances.
Properties:-
* A solution is a homogeneous mixture
* The particles of a solution are smaller than 1 nm in diameter.
* The particles of a solution do not scatter a beam of light passing through the solution.
* The solute particles cannot be separated from the mixture by the process of filtration
* A solution is stable.
examples-
Explain the concentration of a solution, what are the different types of concentration in a solution?
- The amount of solute present in a given amount of solution is called concentration of a solution.
- Solution in which no more solute can be added at a given temperature since it has already dissolved the maximum amount of solute it can, is called a Saturated Solution.
- A solution, in which we can add more amount of solute as it has not achieved its saturation level yet, is called an unsaturated Solution.
- A solution in which the concentration of the solute is much less than that of the solvent is called dilute solution.
- A solution with a large amount of solute is called a concentrated solution is called concentrated solution.
What is solubility?
The amount of solute present in a saturated solution at a given temperature is called its
solubility. It varies with temperature.
Formulas to find concentration of a solution.
Concentration can be expressed as:
Mass by mass percentage of a solution =
𝑴𝒂𝒔𝒔 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒆 / 𝑴𝒂𝒔𝒔 𝒐𝒇𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏 × 𝟏𝟎𝟎
Mass by volume percentage of a solution =
𝑴𝒂𝒔𝒔 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒆 / 𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏 × 𝟏𝟎𝟎
Volume by volume percentage of a solution =
𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒆 / 𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏 × 𝟏𝟎𝟎
What is a suspension? State its properties
It is formed when two or more substances are mixed in a non-uniform manner. The solute does not mix with the solvent and can be seen with naked eyes. Eg- Chalk powder in water.
- heterogenous mixture
- particles can be seen through the naked eye
- scatter a beam of light passing through it and make its path visible.
- seetle down when a suspension is left undistubed (unstable). Can be seperated through filtration. Once particles settle down, suspension breaks and the particles settle down.
*
What is a colloidal solution?
State its properties
A colloidal solution or a colloid is a mixture of two or more substances in which particles are uniformly spread throughout the solution. The particles are usually very small, so that the solution appears as a homogeneous mixture but it is not, it is heterogeneous. Eg- Milk in water.
- A heterogeneous Mixture
- Size of particles of a colloid is too small to be indivisually seen by naked eyes.
- Big enough to scatter a beam of loght passing through it and make its path visible.
- They do not settle down when left undisturbed (stable)
- Cannot be seperated by filtration, special technique called centrifugation is used.
What is solute and solvent?
SOLUTE: The component of the solution that is dissolved in the solvent. (Usually lesser quantity)
SOLVENT: The component of the solution that dissolves the other component in it is called solvent.
(Usually in larger quantity)
Give the types of colloids with examples.
Liquid + Gas = Aerosol -> Fog, clouds, mist
Solid + Gas = Aerosol -> Smoke, automobile exhaust
Gas + Liquid = Goam -> Shaving cream
Liquid + Liquid = Emulsion -> Milk, face cream
Solid + Liquid = Sol -> Milk of magnesia, mud
Gas + Solid = Foam -> Foam, Rubber, sponge, pumice
Liquid + Solid = Gel -> Jelly, cheese, butter
Solid + Solid = Solid Sol -> Coloured gemstones, milky glass
What are the components of colloidal solutions?
DISPERSED PHASE: The dispersed particles or the solute-like components in a colloid.
DISPERSING MEDIUM: The substance in which these solute-like particles are dispersed OR dispersed
phase is dispersed.
Difference betwen physical and chemical change.
Physical Change
1. Only physical properties such as colour physical State, density, volume etc change, chemical properties remain unchanged.
2. No new substance is formed
3. Very little energy in the form of light or heat is given or absorbed during physical change.
4. Temporary change
5. Original form of substance can be regained using physical methods.
6. physical change is reversible.
Chemical Change
1. Chemical composition and properties change.
2. New substance is formed
3. Always accompanied by absorption or evolution of energy
4. Permenant Change
5. Cannot be obtained by simple physical methods.
6. Irreversible.
What are elements?
State properties of elements.
An element is the basic form of matter that cannot be broken down into simpler substance by chemical reaction. They are of three types Metals, Non-metals and Metalloids.Robert Boyle was the first scientist to use the term element in 1661.
Properties-
* Have lustre (shine)
* silver-grey or golden-yellow colour.
* conduct heat and electricity
* ductile (can be drawn into wires)
* Malleable (can be hammered into thin sheets)
* sonorous (make a ringing sound when hit.
What are the three types of elements.
METALS: Elements that are hard, lustrous, malleable and ductile & good conductors of heat and electricity.
Eg- Gold, Silver, Copper, Iron, etc.
NON-METALS: Elements that are soft, non-lustrous, brittle & poor conductors of heat and electricity. (also display variety of colors) Eg- Hydrogen, Oxygen, Sulphur, Phosphorus, etc.
METALLOIDS: Elements which have properties between metals and non-metals. Eg- Boron, Silicon,
Germanium, etc.
What are compounds?
A compound is a substance composed of two
or more elements, chemically combined with
one another in a fixed proportion.
Difference between compounds and mixtures.
Compounds -
1. Elements react to form new compounds.
2. The composition of each new substance
is always fixed.
3. The new substance has totally different properties.
4. The constituents can be separated only
by chemical or electrochemical reaction
Mixtures-
1. 1. Elements or compounds just mix together to form a mixture and no new compound is formed.
2. A mixture has a variable composition
3. A mixture shows the properties of the constituent substances.
4. The constituents can be seperated 4. The constituents can be separated only fairly easily by physical methods.
