Chemistry Jan 7 Specific Heat Heating Cooling Specific
- Slides: 9
Chemistry Jan 7 Specific Heat, Heating, Cooling
Specific Heat – the amount of heat it takes to raise the temperature of 1 g of the substance 1○ C. Each substance has its own specific heat (Cp), including water, ice, steam. Cp = q m X ΔT heat (joules or calories) mass (g) X change in temp (C)
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.
When 25. 0 m. L of water containing 0. 025 mol HCl at 25 C is added to 25. 0 m. L water containing 0. 025 mol Na. OH at 25. 0 C in a foam cup, a reaction occurs. Calculate the enthalpy change (in k. J) during the reaction if the highest temperature is 32 C. Assume the densities of the solutions are 1. 00 g/m. L.
Thermochemical Equations Use heat of reaction to calculate thermochemical change. 2 Na. HCO 3(s) + 129 k. J → Na 2 CO 3(s) + H 2 O(s) + CO 2(g) How much heat is required to decompose 2. 24 mol Na. HCO 3(s)?
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.
How many grams of ice at 0 C will melt if 2. 25 k. J of heat are added?
How much energy is necessary to convert 10. 0 g of ice at -20. 0 C to steam at 125 C?
