Conservation of Energy
What states energy cannot be created or destroyed, but can be converted from one form to another?
First Law of Thermodynamics
What is the minimum amount of energy needed to start a reaction?
Activation Energy
What is the theory that successful collisions result in a chemical reaction that releases or absorbs energy ?
Collision Theory
What is the change in mass during a chemical reaction?
None; rearranges
NaOH + HCL -> H2O + NaCl + 57.9 kJ/mol
Is this chemical reaction endothermic or exothermic?
Exothermic
What is the energy held by an object because of its position relative to other objects?
Potential Energy
What is a reaction that releases energy?
Exothermic Reaction
What are the units of specific heat?
Joules per gram degrees Celsius
What is the change in energy during a chemical reaction?
None; rearranges
NH4NO3 + 650.9 kJ/mol -> NH4+ + NO3-
Is this reaction endothermic or exothermic?Endothermic
What is the energy an object possesses due to its motion
Kinetic Energy
What is a reaction that absorbs energy?
Endothermic Reaction
What two scenarios would explain why collisions between two reacting particles do not always result in the formation of a product?
1. Orientation of molecules
2. Speed of reaction is too slow
What 3 things are required for a reaction to occur?
1. Energy
2. Collisions
3. Activation energy
25.0 g of mercury is heated from 25°C to 155°C, and absorbs 455 joules of heat in the process. What is the Cp ?
0.14 J/g degrees C
What is the energy needed to break bonds between atoms?
bond energy
What is the amount of thermal energy in a system at constant pressure?
Enthalpy
What five factors affect reaction rate?
1. Concentration
2. Temperature
3. Surface Area
4. Catalysts
5. Pressure
What happens to the concentration of a reaction when the reaction rate decreases?
The concentration of the reactants decreases and the concentration of the products increases.
2NH4Cl -> 2NH4+ + 2Cl-
Calculate the enthalpy for the reaction
NH4Cl =-315 kJ/mol NH4=-133 kJ/mol
Enthalpy= -896 kJ/mol
What is a measure of the amount of kinetic energy in substance that can be measured using a thermometer?
Temperature
What type of reaction took place if the enthalpy was negative?
Exothermic Reaction
What effect will increasing the temperature of the reactants have on the reaction?
Will speed up the reaction.
What is the equation for enthalpy?
Enthalpy of Reaction = (enthalpy formation of products) - (enthalpy formation of reactants)
ΔHrxn = ΔHf(products) - ΔHf(reactants)
Calculate the amount of heat released when a bottle of water (150g) is cooled from 20 C to 17 C. The specific heat of water is 4.18 J/g C.
Q= -1,881 J