Term
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Definition
| A chemical reaction which evolves heat |
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Term
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Definition
| A chemical reaction which absorbs heat |
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Term
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Definition
| The heat content of a system |
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Term
| Enthalpy Change (State the equation) |
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Definition
The difference in het content between the products and the reactants
ΔH = ΣHProducts - ΣHReactants |
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Term
| Exothermic Reaction: ΔH is (positive or negative) |
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Definition
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Term
| Exothermic Reaction: Enthalpy is (increasing or decreasing) |
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Definition
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Term
| Endothermic Reaction: ΔH is (positive or negative) |
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Definition
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Term
| Endothermic Reaction: Enthalpy is (increased or decreased) |
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Definition
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Term
| List in the order of increasing enthalpy: Liquid, Solid, Gas |
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Definition
Solid (least enthalpy)
Liquid
Gas (most enthalpy) |
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Term
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Definition
A balanced chemical equation which includes the enthalpy change.
H2(g) + ½O2(g) →H2O(l)
Δ H=-285kJ |
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Term
| In a thermochemical equation, what happens to ΔH when the moles of reactants double? |
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Definition
| Enthalpy is directly proportional to mass. Therefore, when the moles double, so does ΔH. |
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Term
Reverse Reaction What is the reverse reaction of:
C + O2 → CO2 |
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Definition
Products becoming reactants
CO2 → C + O2 |
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Term
| How are ΔH for a forward and ΔH for a reverse reaction related? |
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Definition
| ΔH forward is equal in magnitude but opposite in sign to ΔH reverse. |
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Term
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Definition
| ΔH for a reaction is the same regardless of the path traveled from reactants to products |
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Term
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Definition
| The molar heat of formation of a compound is equal to ΔH when 1 mole of compound is formed from its elements at 1 atm. and 25°C. |
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Term
| Write the general equation to calculate ΔH for a chemical reaction. |
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Definition
ΔH = ∑(ΔHF(products)) - ∑(ΔHF(reactants))
ΔHF = Heat of Formation |
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Term
| What is the heat of formation of an element in its most stable state? |
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Definition
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Term
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Definition
| A device used to measure the quantity of heat liberated or absorbed in a chemical reaction or physical change |
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Term
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Definition
| The amount of heat required to raise one gram of substance 1°C |
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Term
| Give the specific heat value for liquid water in calories and Joules. |
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Definition
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Term
| Give the specific heat value for liquid water in Joules. |
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Definition
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Term
| Write an equation to calculate energy change when a fixed mass of substance changes temperature. |
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Definition
ΔH = mCpΔT
m = mass in grams
T = temperature change
Cp = specific heat
ΔH = heat absorbed, released |
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Term
| How many calories to raise 100 grams of water from 20°C to 30°C |
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Definition
ΔH = mCpΔT
Heat = (100g)(1 cal/g°C)(10°C)
Heat = 1000 cal |
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