| Chapter 6 |
| The Heat Capacity of Water= 4.184J/gC |
| qm=-qm |
| Formulas: |
| q= (specific heat capacity) (mass) (change in temperature) |
| q= (heat capacity) (change in temperature) |
| w= (-p) (change in volume) |
| Delta H= (EChange in Hp) - (EChange in Hr) |
| Examples: |
| 2.41x10^4 J are needed to raise the temperature of 105.0g of Mg from 25.0C. What is the heat capacity of Mg? q= (specifc heat capacity) (mass) (change in temp.) 2.41x10^4J= (SH) (105.0g) (250-25) x= 1.02 J/gC |
| Ex 1) |
| Ex 2) |
| The Delta H value for the reaction: 1/2 O2 (g) + Hg (l) --> HgO(s) is -90.8 kJ/mol How much heat is released when 32.5 Hg is reacted with Oxygen? 32.5g Hg 1 mol Hg ---------- x --------------- = .162 mol Hg 1 200.59 gHg -90-8 kJ 1.62 mol ---------- x -------------- = 14.7 kJ mol 1 |
| Ex 3) |
| C+O2 --> CO2 delta H= -393.5 kJ/mol S+O2 --> SO2 delta H= -296.9 kJ/mol CS2+3O2 --> CO2 + 2SO2 delta H= -1075.2 kJ/mol What is the Delta H for the reaction: C+2S --> CS2 C+O2 --> CO2 -393.5 kJ/mol 2SO2 + CO2 --> 3O2 + CS2 1075.2 C + 2SO2 --> 2O2 + CS2 2S+2O2 --> 2SO2 -593.9 C=2SO2+2S+2O2-->2O2+CS2+2SO2 C+2S--> CS2 Answer: 87.8 kJ/mol |