1. Specific Heat, Heating, Cooling
Chemistry Jan 7
Specific Heat, Heating, Cooling

2. Specific Heat – the amount of heat it takes to raise the temperature of 1g of the substance 1○ C. Each substance has its own specific heat (Cp), including water, ice, steam. Cp = q heat (joules or calories) m X ΔT mass (g) X change in temp (C)

3. Enthalpy is the heat content of a system (H)
Enthalpy is the heat content of a system (H). The heat released or absorbed by a reaction is the same as change in enthalpy (ΔH), which will be the same as heat (q) So, q = ΔH If heat is absorbed, this is a negative number.

4. When 25.0 mL of water containing mol HCl at 25 C is added to 25.0 mL water containing mol NaOH at 25.0 C in a foam cup, a reaction occurs. Calculate the enthalpy change (in kJ) during the reaction if the highest temperature is 32 C. Assume the densities of the solutions are 1.00g/mL.

5. Thermochemical Equations
Use heat of reaction to calculate thermochemical change.
2NaHCO3(s) + 129kJ → Na2CO3(s) + H2O(s) + CO2(g)
How much heat is required to decompose 2.24 mol NaHCO3(s)?

6. Heat in Changes of State ΔHfus = heat absorbed by 1 mole of solid as it melts to liquid. ΔHvap = heat absorbed by 1 mol of liquid vaporizing.

7. How many grams of ice at 0 C will melt if 2.25 kJ of heat are added?

9. How much energy is necessary to convert 10. 0 g of ice at -20
How much energy is necessary to convert 10.0 g of ice at C to steam at 125 C?