Unit 6 - Chemical Reactions Flashcards
Law of Conservation of Mass
The total mass is conserved
The Conservation Laws
A system is part of the universe being studied
It is a closed system if nothing can enter or leave
If a system isn’t closed with respect to something then that thing can enter or leave; thus we say it is an open system, with respect to that thing
Law of Conservation of Atoms
The total number and type of atoms is conserved
Law of Conservation of Charge
Total electrical charge is conserved
Law of Conservation of Energy
Total energy is conserved
Most compounds containing metals (ionic compounds) are what at room temperature?
What state are they when dissolved in water?
Solids
Aqueous state
Phenyl Thalene
An indicator to see if something’s a base
It will turn bases pink
Acids
Substances that can release a proton when dissolved to form aqueous solutions
Bases
Substances that can release a hydroxide group when dissolved in aqueous solutions
Salts
Ionic substances that are neither acids nor bases
Enthalpy
The total amount of energy contained in a system H
Energy must be input to break reactant bonds, energy is then output when product bonds form. Energy input always different from the energy output. Thus the amount of energy stored before and after is different. This change in NRG, is represented with
Exothermic Reactions
Chemical reactions that release energy to their surroundings
Total amount of Ep and Ek is constant in a closed system. Since the amount of Ep is lower in products it must be true that Ek (of products) is higher (more Ek means higher temp). Since most systems aren’t closed WRT NRG, the surroundings heat up
Endothermic Reactions
Reactions that absorb energy from their surroundings
Since the amount of Ep is greater in products it must be true that Ek of products is lower (less Ek means lower temp). Since most systems aren’t closed WRT energy, heat energy will be absorbed from the surroundings.
Activation Energy, Ea
The energy “push” needed to start any chemical reaction
Miscellaneous
Enthalpy measured in Joules
Thermochemical Equations include the energy term
Exothermic: energy term in products
Endothermic: energy term in reactants
Writing explicitly: exo -
endo +
