Vocabulary
Define heat
Transfer of thermal energy from one object to another
Endothermic reactions have a ________ q value.
positive
How much heat is needed when 40.7 grams of water (specific heat of 4.18 J/gC) goes from 14.0 C to 18.0 C?
681 J
Sections of graph with increasing kinetic energy
A,C,E (solid, liquid, and gas phase)
When you have an endothermic reactions, enthalpy has a _______ value and is written with the ___________ in a thermochemical equation.
Positive, reactants
Define specific heat
Energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius.
In an exothermic reaction, the energy of the products is ____________ than the reactants.
Lower
What type of specific heat would you want if you want an object to heat up slowly?
High specific heat
What phase of matter has the highest kinetic energy?
Gas
Rewrite C + O2 --> CO2 DeltaH: -393.5 kJ as a thermochemical equation
C + O2 --> CO2 + 393.5 kJ
Define first law of thermodynamics
Energy cannot be created nor destroyed
A reaction takes place in a beaker. Afterwards, the beaker feels cold to the touch. What type of reaction?
Endothermic
What is the final temperature of a 35 grams piece of metal with a specific heat of 0.342 J/gC that is initially at 20.0C and absorbs 507 J of heat
62 C
How much energy is absorbed when 43 grams of NH3 is converted from a solid to a liquid?
Heat of fusion: 5.65 kJ/mol
Heat of vaporization: 23.5 kJ/mol
14 kJ
Using the equation: 2H2 + O2 --> 2H2O + 571 kJ
How much energy is released when 4.2 moles of oxygen is used?
-2400 kJ
Define the 0th law of thermodynamics
Heat flows from hot to cold until thermal equilibrium is reached
50 grams of methanol gas is condensed into 50 grams of liquid methanol. This process is________
Exothermic
What is the specific heat of a 50.0 gram piece of metal that absorbs 345 J and raises its temp from 10.0C to 18.0C?
0.938 J/gC
How much energy is released when 78 moles of H2O is converted from a gas to a liquid
Heat of fusion:6.01 kJ/mol
Heat of vaporization: 40.7 kJ/mol
-3100 kJ
In the reaction C2H5OH + 3O2 --> 2CO2 + 3H2O + 1368 kJ
How much energy is released when 12.5 of ethanol (C2H5OH) is used?
-371 kJ
What is enthalpy and what is its units?
Change in heat. Units: kJ/mol
How do you find activation energy in a potential energy diagram and can it ever be negative?
Subtract top of hill by the reactants. Should always be positive
The ΔH for the solution process when solid lithium bromide (LiBr) dissolves in water is –48.8 kJ/mol.When 14.5 g of LiBr dissolves in 120.0 g of water, the temperature increases from 24.0°C to _____ °C. Assume the solution has a specific heat of 4.18 J/g°C
40.2C
How much energy is released when 12 grams of C2H5OH is converted from a liquid to a solid
Heat of fusion: 4.60 kJ/mol
Heat of vaporization: 43.5 kJ/mol
-1.2 kJ
In the reaction CaO + H2O + 65.2 kJ --> Ca(OH)2
How many grams of CaO is needed to absorb 168 kJ?
145 g