density and particle model Flashcards
how to calculate density
density = mass divided by volume
what is density
measure of compactness of a substance
required practical : investigating density of regularly shaped object
method :
1) for each of selected objects measure and record length width and height
2) calculate the volume of each object
3) record your results in a table
4) measure the mass of each object using the digital balance and record results in the table
5) calculate and record density of each object using density = m divided by v
6) standard units of density are kg/ m cubed.
required practical : density of an irregularly shaped object
1) measure the mass of one of the irregular shaped objects
2) record results in a table
3) put the displacement can on your desk. put an empty beaker under the spout and fill the can with water. water should be dripping from the spout and you should wait until you see this stop
4) then put a measuring cylinder that you think will give the most accurate reading under the spout instead of the beaker
5) very carefully lower the object into the displacement can so it can be completely submerged . collect all of the water that comes out of the spout in the measuring cylinder
6) measure the volume of collected water. this volume is equal to the volume of the object
7) calculate and record density of the object
8) repeat the activity for some other objects & remember to refill the can with water each time
solid
particles are fixed regular arrangement
particles vibrate and don’t hv much energy
most dense
strong force of attraction between particles
gases
least dense
no forces of attraction between particles
particles are free to move - travel in random directions
particles have more energy and move at hugh speeds
liquids
least dense than solids
weaker forces of attraction between particles
particles close together , but can move past each other, form irregular arrangement
particles have some energy, they move at low speeds
what is internal energy
the total kinetic energy and potential energy (due to position ) all of the particles of a system
what changes the internal energy of a substance
heating changes internal energy of a substance because in solids and liquids the potential and kinetic energy increases
why does heating cause ice to turn into liquid water
heating a system transfers the energy to the particles (gain more energy in their kinetic energy stores and move faster ) therefore increasing the internal energy
the change of state occurs if the substance is heating enough and there is enough energy in the particles kinetic energy store to break the bonds holding the particles together
what is specific latent heat
the energy needed to change the state of a 1kg mass
how does temperature change gas pressure
the higher the temperature the higher the avergae energy therefore the speed of particles increase, therefore the particles of an average collide with the container surface with the most force and move particles
what is the law of displacement
the law of displacement says that an object completely submerged in a fluid (like water) will replace an amount fluid equal to its own volume
if an object floats..
it’s density must be lower than the density of the fluid
change in internal energy equation
change in internal energy= mass x specific heat capacity x temperature change
