AP Heat Flashcards
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| 14372376692 | First Law of Thermodynamics | Energy lost by one object must be gained by another object | 0 | |
| 14372376693 | How heat can be applied in a handshake | Heat is transferred from hotter hand to colder hand | 1 | |
| 14372376694 | Exothermic reaction | Product bonds are stronger Heat is a product (released) ΔH is negative | 2 | |
| 14372376695 | Endothermic reaction | Reactant bonds are stronger Heat is a reactant ΔH is positive | 3 | |
| 14372376703 | Equation for change in enthalpy | q = mCΔT | 4 | |
| 14372376704 | What is the specific heat needed for 2.98 g of aluminum (specific heat of 0.98 J/g°C) to be heated from 21.6°C to 29.8°C? | q = 2.98 g * (0.98 J/g°C) * 8.2°C = 24 J | 5 | |
| 14372376705 | High specific heat | Heats/cools slowly (Takes a lot of energy to change temperature) | 6 | |
| 14372376706 | Low specific heat | Heats/cools quickly (Only a small amount of energy needed to change temperature) | 7 | |
| 14372376707 | A piece of copper is heated to a temperature of 91°C and placed into 125 g of water at 25°C (C of copper = 0.39 J/g°C). What mass of copper was used? | q(H2O) = 125 g * 4.18 J/g°C * (27-25)°C = 1000 J 1000 J = m * 0.39 J/g°C * (91-27)°C m = 40 g | 8 | |
| 14372376708 | What is the specific heat of zirconium if 2514 J is required to raise 298 g of the substance from 23.0°C to 52.8°C? What is it's molar heat capacity? | 2514 J = 298 g * (C) * 29.8°C C = 0.283 J/g°C * (91.224 g/mol) = 25.8 J/mol | 9 | |
| 14372376709 | 1.40 g of wax (C25H52) is burned over 400 g of water. When burned, the temperature of the water goes from 25°C to 76°C. Find the heat of combustion per gram AND per mole of wax. | q = 400 g * (4.18 J/g°C) * 51°C = 85000 J 1.40 g * (1 mol / 355.07 g) = 0.00394 mol 85 kJ / 1.40 g = -61 kJ/g 85 kJ / 0.00394 mol = -22000 kJ/mol | 10 | |
| 14372376710 | Ethanol is combusted in the air, with the ΔH of the reaction being -1367 kJ/mol ethanol. How much heat is released when 3.88 g of ethanol is burned in excess oxygen? | C2H5OH + 3O2 → 2CO2 + 3H2O 3.88 g C2H5OH * (1 mol C2H5OH/46.06904 g) * (1367 kJ/1 mol) = -115 kJ | 11 | |
| 14372376711 | How much heat is released when 12.4 g of ethanol react with 22.3 g O2? | 12.4 g C2H5OH * (1 mol C2H5OH/46.06904 g) = 0.269 mol C2H5OH 22.3 g O2 * (1 mol O2/31.9988 g O2) * (1367 kJ/3 mol O2) = -318 kJ | 12 | |
| 14372376712 | Hess's Law | the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process | 13 | |
| 14372376725 | FeO(s) + CO2(g) → Fe(s) + CO2(g) ΔH = ? |  | 14 | |
| 14372376726 | Acetylene is combusted in the air. Find the ΔH° of the overall reaction from: H2(g) + 1/2O2(g) → H2O(l): ΔH° = -285.8 kJ 2C(s) + H2(g) → C2H2(g): ΔH° = +226.7 kJ C(s) + O2(g) → CO2(g): ΔH° = -393.5 kJ |  | 15 | |
| 14372376713 | Heat of formation | Must come from its ELEMENTS | 16 | |
| 14372376727 | Find the heat of formation for the following reaction: 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) |  | 17 | |
| 14372376728 | Find the standard heat of formation of hexane (C6H14) given the overall heat of combustion is -4141 kJ/mol |  | 18 | |
| 14372376729 | Draw and label a heating/cooling curve |  | 19 | |
| 14372376730 | Calculate the total heat energy in Joules needed to convert 20 g of substance X from -10°C to 70°C given the following: Specific heat (C) of solid phase = 2.0 J/g°C Melting point = 12°C Heat of fusion = 0.232 kJ/mol Specific heat (C) of liquid phase = 5.0 J/g°C Boiling point = 63°C Heat of vaporization = 12000 J/g Specific heat (C) of vapor phase = 1.0 J/g°C |  | 20 | |
| 14372376714 | Entropy | A measure of disorder or randomness. | 21 | |
| 14372376715 | Activation energy | the minimum amount of energy required to start a chemical reaction | 22 | |
| 14372376716 | Heat capacity | the amount of heat needed to increase the temperature of an object exactly 1°C | 23 | |
| 14372376717 | Open system | A system in which matter can enter from or escape to the surroundings. | 24 | |
| 14372376718 | Closed system | A system in which no matter is allowed to enter or leave | 25 | |
| 14372376719 | State function | a property of the system that changes independently of its pathway | 26 | |
| 14372376720 | Enthalpy of fusion | the enthalpy change that occurs to melt a solid at its melting point or freeze at its freezing point | 27 | |
| 14372376721 | Enthalpy of vaporization | the amount of energy absorbed as heat when a specified amount of a substance vaporizes at constant pressure | 28 |