Heat
What is heat?
A type of energy. Measured in joules.
Where does energy come from in the universe?
The sun, chemical reactions, radioactive elements (another type of chem reaction), fossil fuels (substances with lots of chemical energy). Food (substances high in chemical energy, which your body is able to extract).
What can you measure with a calorimeter?
The amount of chemical energy in a substance.
What is the formula for the kinetic energy of an object?
k.e. = 1/2 mass x velocity2
The S.I. Unit for Energy
Joule
How is heat transferred?
Hot molecules move and can bump into other molecules, making them move.
What is mechanical energy?
Total kinetic energy + potential energy
How do you release the chemical energy in a substance?
Burn it up.
What is the formula for gravitational potential energy of an object?
g.p.e. = mass x g x height
g is the universal acceleration due to gravity (10m/s2)
Another unit for energy (not SI)
Calorie (you find this on the box of Cheerios)
What piece of equipment do you use to measure heat?
thermometer.
Can energy ever disappear?
No! The amount of energy in the universe is constant. Energy just changes form from kinetic to potential to chemical to heat to kinetic.
How does a calorimeter trap the chemical energy released by a substance?
The energy is absorbed (soaked up) by the water in the calorimeter.
What equation can you use to calculate the amount of heat or chemical energy in a substance?
q (heat) = mass x heat capacity x change in temperature
Each substance has a heat capacity. What does it describe?
Heat capacity tells you how much heat the substance can absorb before it starts to heat up. Things with high heat capacity can absorb lot of heat from a chemical reaction without heating up too much.
How is kinetic energy releated to temperture?
Gasses at higher temperature have more kinetic energy.
Can energy ever appear?
No! It must have come from somewhere. So where did the sun get all of its energy? Many different things are happening on the sun. Some of its energy comes from the gravitational collapse of material on the sun. This is potential energy being converted into light an heat energy. Awesome!
Released that energy into a known amount of water and measured the temperature change of the known amount of water.
What is the equation for the amount of energy before a transformation and after the transformation?
energy before = energy after
What are the units for work?
Work is force x distance (how hard you are pushing x how far you pushed).
Same as the units for energy! Joules.
Heat capacity is a characteristic property of metals. You can use the heat capacities that you measured to determine what metals you were working with. What do you need to do this?