Download presentation

1
**15.3 Thermochemical Equations**

Pages 529 – 533

2
**A. Thermochemical Equations**

A thermochemical equation is a balanced chemical equation that includes the physical states of all reactants and products, and energy change In a thermochemical equation, the enthalpy of change for the reaction can be written as either a reactant or a product

3
**A. Thermochemical Equations**

How to write thermochemical equations: Endothermic (positive ΔH) 2NaHCO3(s)+ 129kJ Na2CO3(s) + H2O(g) + CO2(g) Exothermic (negative ΔH) CaO(s) + H2O(l) Ca(OH)2(s) kJ

4
**B. Thermochemical Equation Practice**

Write the thermochemical equation for the addition of oxygen gas to solid iron (III) if the ΔHrxn= kJ Fe(s) O2(g)→ Fe2O3(s) kJ Write the thermochemical equation for the decomposition of sulfur trioxide gas into sulfur dioxide gas and oxygen gas if the ΔHrxn= 198 kJ SO3(g) kJ → SO2 (g) + O2 (g) Exothermic 4 3 2 Endothermic 2 2

5
15.4 Hess’s Law Pages 534 – 540

6
A. Hess’s Law Hess’s law states that if you can add two or more thermochemical equations to produce a final equation for a reaction, then the sum of the enthalpy changes for the individual reactions is the enthalpy change for the final reaction 2S(s) + 3O2(g) 2SO3(g) H = ?

7
A. Hess’s Law

8
**B. Hess’s Law Practice N2(s) + 2O2(g) 2NO2(g) H = ? Known:**

N2 (g) + O2(g) 2NO(g) H = -180 kJ 2NO(g) + O2(g) 2NO2(g) H = -112 kJ Build your equation:

9
**B. Hess’s Law Practice 2H2O2(l) 2H2O(l) + O2(g) H = ?**

Known: 2H2(g) + O2(g) 2H2O(l) H = -572 kJ H2(g) + O2(g) H2O2(l) H = -188 kJ Build your equation:

10
**B. Hess’s Law Practice 2S(s) + 3O2(g) 2SO3(g) H = ? Known:**

S(s) + O2(g) SO2(g) H = -297 kJ 2SO3(g) 2SO2(g) + O2(g) H = 198 kJ Build your equation:

11
**B. Hess’s Law Practice 2B(s) + 3H2(g) B2H6(g) H = ?**

Known: 2B (s) + 3/2O2(g) B2O3(s) H = kJ B2H6(g) + 3O2(g) B2O3 (s) + 3H2O (g) H = kJ H2 (g) + ½ O2(g) H2O (l) H = -286 kJ H2O (l) H2O (g) H = 44 kJ Build your equation:

Similar presentations

Presentation is loading. Please wait....

OK

Thermochemistry.

Thermochemistry.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google