IB SL Chemistry Unit 5 | Kentucky State University

University:
Kentucky State University
Course:
CHE 101 | General Chemistry I
Academic year:

2023
Views:

204

Pages:

3
Author:

accionox1v

UNIT FIVE ● HEAT ○ Transfer of energy between two objects of different temperature. ○ Heat is not the same as temperature ○ Heat content is enthalpy, measured as 𝛥𝐻 ○ Measuring Heat in a system ○ Use the equation 𝑞 = 𝑚𝑐𝛥𝑇 ○ C is specific heat of water ○ T is temperature in kelvin ○ M is mass in grams. ○ 𝛥𝐻 = 𝑄/𝑛 where n is moles of the limiting reactant ● Temperature- measure of average kinetic energy in a system ● Exothermic Vs endothermic reaction ○ Exothermic Reaction releases heat. This means that the surroundings will become hotter as the system releases heat. ○ Endothermic reaction absorb heat, leaving the surroundings cooler as the system becomes hotter ● Hess Law ○ Heat is a state function- final value is independent of the path the reaction takes ○ As long as you reach the final temperature, that’s what matters. ○ We can visualize this through enthalpy cycles ○ Overall enthalpy chart for a reaction. Doesn’t matter if the reactant goes directly to the product or through an intermediate reaction, it just needs to reach the product. ○ 𝛥𝐻3 = 𝛥𝐻1 + 𝛥𝐻2 ● Enthalpy of formation ○ In the comp book you’ll be given enthalpy values. Subtract reactant from product to get total enthalpy. ● Enthalpy of combustion ○ Use enthalpy of combustion values given in the comp book. Subtract product from reactant to find total enthalpy. ● Enthalpy change ○ Total sum of reactants enthalpies - total sum of products enthalpies ● Haber Process- Need to know ○ N2 (g) + 3H2 (g) ⇌ 2NH3 (g) ○ One N triple bond broken ○ Three h-h bonds broken ○ Six n-h bonds formed ○ Take relevant enthalpies and multiply by amounts of each bond, then subtract products from reactants.