Topic 1 - Solids, Liquids and Gases Flashcards
Heat, Thermal equilibrium, Temperature, Brownian motion, Thermal energy, SHC, Latent heat, Amount of a substance
What is the triple point?
At one specific temperature and pressure the three phases of matter of a substance can exist in thermal equilibrium
What is thermal equilibrium?
No net transfer of thermal energy between the phases
What is temperature?
Temperature is a measure of the hotness of an object/A bulk measure of the internal energy of a system of molecules
What is the relationship between temperature and internal energy?
Temperature is proportional to the amount of internal energy in a substance
What is heat?
If the temperature of one object is higher than another object there is a net flow of thermal energy from the hotter object to the colder one, this is known as “heat”. When the object reaches thermal equilibrium they will be at the same temperature
What is the zeroth law in of thermodynamics?
If 2 objects are each in thermal equilibrium with a third, then all 3 are in equilibrium with each other
How is temperature measured?
In order to measure temperature a scale is needed that includes 2 fixed points at defined temperatures
How was Celsius discovered?
In 1742 a Swedish astronomer Anders Celsius proposed using a scale with the 2 fixed points as the freezing and boiling point of pure water (when the atmospheric pressure is 1.01x10^5) with 100 degrees between 0 degrees and 100 degrees
What are the problems with the Celsius?
The 2 fixed points vary slightly depending on the surrounding atmospheric pressure
What is the absolute temperature scale?
It uses the triple point of pure water and absolute zero as its fixed points
What SI base unit of temperature is used for the absolute scale?
Kelvin (K)
What us the lowest value of Kelvin?
0K, here the atoms have the minimum internal energy and all classical atomic motion stops. At this point a change of 1K equals a change of 1 degrees
What is the equation you can use to convert between Kelvin and Celsius?
T(K) = (Celsius) + 273
What is the kinetic model?
It describes how all substances are made up of atoms or molecules, which are arranged differently depending on the phase substance
How are solids arranged?
The atoms/molecules are regularly arranged and packed closely together, with strong electrostatic forces holding them in a fixed position, but they can vibrate and so have kinetic energy
How are liquids arranged?
The atoms/molecules are still and very close together, but they have more Ek than solids so can change positions and flow past each other
How are gases arranged?
The atoms/molecules have much more Ek than in liquids, they are much further apart. They’re free to move past each other as there are negligible electrostatic forces between them, unless they collide with each other or the container walls. They move randomly with different speeds in different directions
Brownian motion
It explains the random motion of very small particles suspended in a liquid or gas. The small particles move as a result of collisions with the atoms and molecules that make up the liquid or gas
How does a particle’s phase relate to its density?
Generally a substance is most dense in its solid phase and least dense in its gaseous phase
How does water differ from different elements regarding density?
Water freezes into a regular crystalline pattern held together by strong electrostatic forces between the molecules. In this structure the molecules are held slightly further apart than in their random arrangement in liquid water, so ice is slightly less dense
What is the internal energy of a substance?
The sum of the randomly distributed kinetic and potential energies of atoms/molecules within the substance
What is the formulae for total kinetic energy
Total kinetic energy = Total PE + Total KE
How does the internal energy of a body increase?
. Temperature increases the kinetic energy in the body, this makes the atoms/molecules that make up the substance move faster and increases the internal energy
. When a substance changes phase the electrostatic potential energy increases significantly
Define SHC
The energy required to increase the temperature of an object with a mass of 1kg by 1K
SHC equation
E=mC(change in temperature)
Define Specific latent heat
The energy required to change the phase of 1kg of a substance at a constant ttemperature
Specific latent heat of fusion
Solid - Liquid
Specific latent heat of vaporisation
Liquid - Gas
Specific latent heat equation
E=mL
What happens to the energy of a body when the temperature increases?
The kinetic energy increases
The potential energy stays constant
The total energy increases
What happens to the energy of a body during the phase?
The kinetic energy stays constant#
The potential energy increases
The total energy increases
What is the amount of a substance?
The amount of a substance is measured in moles. One mole of a substance contains 6.02x10^23 atoms/molecules
What is the equation linking the number of moles of a substance, Avogadro’s constant and the number of atoms/molecules in a substance?
N=n.Na
The number of atoms/molecules in a substance) = (number of moles of a substance).(Avogadro’s constant
What is the equation linking the number of moles of a substance, the mass of a substance in grams and the molar mass of the substance (g/mol)?
n=m/V
The number of moles of a substance) = (The mass of a substance (g)).(The molar mass of the substance (g/mol)
What is the equation for density?
Density = Mass/Volume
