Bonds and Energy and Stuff
What type of bonds are broken during a phase change?
Intermolecular bonds
What sign so you use (+ or -) if a system is liberating energy?
(-)
What are the two ways to manipulate a reaction according to Hess's Law
What types of reactions are in the reaction mechanism?
elementary reactions
There’s only one letter that doesn’t appear in any American state name. What is it?
Q
There's a Z in Arizona and X in Texas
As potential energy increases, do bonds become longer or shorter? more stable or less stable?
Bonds become longer and less stable.
T of F: if the surroundings is doing the work the sign will be positive (+)
True!
The sign would be negative if the system does the work (-).
A substance is cooling and going from a gas phase to a solid phase. Is this an endothermic or exothermic process?
Exothermic!
List the 3 types of elementary reactions
Unimolar, Biomolar, and Termolar.
What is the probability of a blue lobster existing?
One in two million
What is the specific heat capacity of water?
4.184 J/gC
A system has 223 J of work done on it and then is heated through the addition of 72 J of thermal energy. What is the change in the internal energy of the system?
=295 J
What equation would you use if a substance is going through a phase change into a gas?
q= mass x delta Hvap
T or F: Molecules must collide in any random way for a reaction to start.
False. Molecules must collide with the proper orientation for a reaction to start.
T or F: The Eiffel Tower can be 15 cm taller during the summer
True! due to thermal expansion meaning the iron heats up, the particles gain kinetic energy and take up more space.
What is the energy associated with bond breaking and making?
Enthalpy
The system loses 0.031 kJ of thermal energy to the surroundings. The system then has 68 J of work done on it. What is the change in the internal energy of the system?
=37 J
What are the requirements for a chemical reaction to be considered a formation reaction?
One mole of product is formed
The product is formed from its elements
The reactants must be in their standard state.
The partial order of reactant A is 2 and the partial order of reactant B is 1. What is the overall order?
What is the national animal of Scotland?
The Unicorn!!
T or F: Chemical reactions involve the making or breaking of intramolecular bonds.
False!
Phase changes are the breaking or making in intermolecular bonds.
Chemical changes are the making and breaking of intramolecular.
The surroundings gain 137 J of thermal energy, which is followed by 13 J of work done by the system. What is the change in the internal energy of the system?
=-150 J
5g of a liquid with a specific heat of 8 J/gC cools from 30 degrees Celsius to 0 degrees Celsius to form a solid. What is the change in energy?
-1200 J/gC
What will be the partial orders of the reactants in an elementary reaction?
the partial orders will be the reactants coefficients.
What is the real name for a "#" symbol
It is called an octothorp. oc·to·thorp