Week 1
A chemical reaction occurs when....
the atoms are rearranged.
The most basic building block of an element.
atom
Why do molecules change phase?
Energy is transferred into the system or energy is transferred out of system
The average kinetic energy is the...
temperature
Keith notices that his metal bike has rust on it. This is a _________ change.
chemical.
The metal is reacting with oxygen in the air.
A physical change occurs when...
the molecules are rearranged.
Anything that has mass and volume
matter
When a solid turns into a liquid?
the sum of all the kinetic energy in an object
Total Thermal Energy
Tremaine is very tired right before school. He decides to mix sugar in his coffee. This is an example of a _____ change.
physical. The sugar does not react with the coffee, it is part of a mixture.
When you boil water on the stove a ________ change occurs, because__________.
composed of 2 or more atoms
molecule
When a gas turns into a liquid?
Condensation
an energy transfer between two objects due to a temperature differnce
heat
Byron swam in a pool, but forgot to bring a towel to dry himself off. Eventually, the water disappears this is an example of a _______ change.
physical.
The water evaporates.
When the mentos was added to the diet coke the _____ rearranged because it was a ________ reaction.
atoms, chemical
mass/volume=
density
Why does condensation occur?
The H20 gas molecules transfer energy to their surroundings.
Can one object transfer energy to another object when they both have the same temperature?
No, when both objects have the same temperature, they have the same average internal kinetic energy. The molecules are moving at the same rate, so net energy transfer will not occur.
matter cannot be created or destroyed
When you break two H2O molecules into 2H2 and O2 a ____________ reaction occurred because the ________ were rearranged.
chemical, atoms
Composed of only one type of molecule or element
Pure Substance
What could you do to cause condensation (think about your drink at a restaurant)?
Fill your drink with ice water. It will cause the H20 gas molecules to transfer energy to cold drink. This energy transfer will cause the water molecules to slow down and become a liquid.
More mass (# of molecules) and add kinetic energy
What do you need to know to show that the law of conservation of mass is followed?
Same number and type of atoms on both side of the equation.