Matter in our surroundings Flashcards
What is matter? How is it classified?
Any object that has mass (kg) and volume (m^3). It is anything in our surroundings. There are two classifications of matter based on physical properties and chemical nature.
What is the physical nature of matter?
Matter is made up of particles, these particles are extremely small and can’t be seen by the naked human eye.
Ex: Potassium permanganate’s crystals in water.
What are the characteristics of the particles of matter?
The characteristics of the particles of matter are:
1. They have space between them
2. They are continuously moving (The kinetic theory of matter)
3. They attract each other.
What is the kinetic theory of matter and changes in states of matter.
The kinetic theory of matter states that all matter has kinetic energy, hence the particles are continuosly moving. States of matter exist because of changes in kinetic energy. When the kinetic energy increases to a certain point the forces of attraction are overcome, changing its state, this can happen in reverse also.
What are the states of matter? Briefly describe them
The states of matter are:
1. Solid - Have definite shape, distinct boundaries and fixed volumes. Have tendency to maintain shape when force applied. Don’t show diffusion
- Liquid - They have no fixed shape but a fixed volume. They flow and change shape, so they aren’t rigid but can be called fluids. Solids, liquids and gases can diffuse into liquids. The rate of diffusion of liquids is higher than that of solids.
- Gas - They are highly compressible as compared to solids and liquids. The liquified petroleum gas (LPG) that we use for cooking or the O2 cylinders in hospitals are compressed gasses. Compressed natural gasses (CNG) us used as fuel these days in vehicles. Gases can diffuse very fast into liquids and gases. The gas particles are moving very fast due to high kinetic energy.
The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.
Change in state of matter.
What is the effect of change of temperature?
When temperature is increased, kinetic energy also increases, hence the particles vibrate and move a lot faster, this helps overcome the forces of attraction between the particles. Solid changes to liquid in a process called melting. Liquid changes to gas in a process called vaporization. This can happen the other way around also. The process of a gas becoming a liquid is called condensation. The process of a liquid becoming a solid is called freezing or solidification. When solid directly changes to gas it is called sublimation. When a gas directly becomes a solid it is called deposition.
What is melting point?
The melting point of a solid is an indication of the strength of the force of attraction between its particles.
When a solid melts, its temperature remains the same, so where does the heat energy go?
The heat gets used up in changing the state by overcoming the forces of attraction between particles. The heat energy is absorbed by the particles, increasing kinetic energy, increasing speed of vibration and helping overcome the forces of attraction. This is called latent heat. Latent means hidden.
What is boiling point?
The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point. Boiling is a bulk phenomenon. The particles from the bulk of the liquid gain enough energy to change into the vapor state.
Change in state of matter.
What is the effect of the change of pressure?
Applying pressure and reducing temperature can liquefy gases. Hence pressure can only change the state of a gas. An example is dry ice or solid CO2, that is directly changes to gas (CO2) in a process called sublimation when pressure is reduced.
What is evaporation?
It is the phenomenon of change of a liquid into vapors at any temperatures below its boiling point.
What is the difference between evaporation and vaporization?
Evaporation:
1. Can happen at all temperatures
2. Can happen below boiling point
3. Occurs is the surface of the liquid
4. Slow and silent
Vaporization:
1. Can happen only at certain temperatures (depends on liquid)
3. Can happen only at the boiling point
3. Occurs through the whole mass of the liquid
4. Fast and vigorous
What are the factors affecting evaporation?
The factors affecting evaporation are:
1. Increase in surface area
Evaporation occurs only at the surface (it is a surface phenomenon), if surface area is increased then the rate of evaporation also increases
- Increase in temperature:
With increase in temperature, more number of particles get enough kinetic energy to go into the vapor state. - Humidity
As humidity increases evaporation decreases - Wind speed.
Increase in wind speed increases rate of evaporation - Nature of liquid
Liquids with low boiling point evaporate faster - Viscosity
If viscosity increases, rate of evaporation increases.
How does evaporation cause cooling?
The particles of a liquid absorb energy from the surrounds to regain the energy lost during evaporation. This absorption of energy from the surrounds makes the surroundings cooler.
What is diffusion?
It is the intermizing of two or more particles of different types of matter.
