L1 - Chemical Reactivity Flashcards
Define ‘energy’.
The ability to do work.
Define ‘work’.
The distance moved against an opposing force.
What is the equation for work?
Work = Force x Distance
What units is energy measured in?
Joules (J)
Define ‘1 Joule’.
The amount of energy required to raise a 1kg substance 10cm against the force of gravity.
Define ‘1 Calorie’.
The amount of heat necessary to raise the temperature of exactly one gram of water by one degree Celsius.
What are the conversions into kcal and cal for 1 calorie.
1 calorie = 1 kcal = 1000 cal
Describe potential energy.
- Stored energy
- Energy due to position
What is the equation for potential energy?
PE = mgh
Describe kinetic energy.
- Energy of motion
- Depends on mass and velocity
What is the equation for kinetic energy?
KE = 1/2mv^2
Describe chemical energy.
- Energy stored in bonds
State the 5 different types of energy.
- Potential energy
- Kinetic energy
- Electromagnetic energy
- Nuclear energy
- Chemical energy
State the ‘First Law of Thermodynamics’ / Law of Conservation of Energy.
“Energy cannot be created or destroyed by any physical and chemical changes - it can only be converted from one form to another.”
What are the conditions for chemical reactions to occur?
- Reactants energetic
- Reactants oriented correctly
Energy is either ________ or ________.
Energy is either released or absorbed.
What is the change in energy?
The difference between bond energies of reactants and products.
Enthalpy change of reaction (ΔH)
Define ‘enthalpy’.
A measure of the heat content of a substance at constant pressure.
What does ΔH° mean?
Heat released / absorbed during a chemical reaction at standard conditions
What is the equation for ΔH°?
ΔH° = H.products - H.reactants
What can you not measure?
Cannot measure the actual enthalpy of a substance (but can measure enthalpy change)
What is the standard state of an element?
- 1 atmosphere
- 25°C