Chem Ch.8

• System: Water
• Surroundings: stove, air, pot itself

The system is the part of an action that is most focused on. The surroundings exchange energy with the system, but are insignificant in comparison with the system.

mass, temperature, and pressure

• A state property is basically a value (or quantity) of something that holds true no mater how that value is reached.
• Ex: delta(T ) because no matter what temperature you started with the delta(T ) value will still the same

The reaction absorbed heat and the temperature of the solution must have dropped so you know it was endothermic.

4.184J

• This is the amount of heat energy needed to raise the temperature of one gram of a certain substance by 1^oC
• It's Units are J/g*^oC

4.18J/g*^oC

q_reaction=-q_calorimeter=-(m_water*c_water)*delta(t)=-C_cal*delta(t)

They aren't the same because Specific Heat instead is the amount of heat needed to raise a single gram of the substance 1^oC hotter unlike Heat Capacity, which is simply the heat needed to raise something 1^oC

Enthalpy

q = deltaH_reaction = deltaH_products - deltaH_reactants

It was endothermic

Thermochemical Equation

-1.20kJ

You would assume the products & reactants are at the same temperature, usually 25^oC

24kJ; this means heat was absorbed

Says that the change in enthalpy of a series of reactions is equal to the summation of the change in enthalpy of each step of that reaction.

• 1) deltaH is directly proportional to amount of reactant or product
• 2) deltaH changes sign when reaction is reversed
• 3) deltaH for a series is equal to the sum of deltaH's in that series

This is the amount of enthalpy change established as true when a compound is formed from the reaction between molecules at a standard pressure (1atm) and a standard temperature (25^oC)

0 kJ

The change in standard enthalpy is equal to the summation of the enthalpies of formation of products minus the summation of the enthalpies of formation of the reactants

This is known as deltaH when one mole of bonds is broken up in the gaseous state...units are kJ/mole

Heat is always absorbed when bonds are broken, and always given off when bonds are formed.

Yes

Bond energies for bonds between 2 different elements are the average of values found from different experiments and should not be used over heats of formation.

Work is all forms of energy other than heat

• Says that the total change in energy of a system is equal to the sum of the heat (q) and work (w) transferred between the system and surroundings.
• deltaE = q + w

• deltaH = q_p (q_p is heat flow at constant pressure)
• deltaE = q_v (q_{v is heat flow at constant volume)}

• H = E + PV
• deltaH = deltaE + deltaPV
• deltaH = deltaE + (delta n_g)RT