Tetraphosphorus decaoxide, P4O10, is an acidic oxide. It reacts with water to produce phosphoric acid, H3PO4, in an exothermic reaction. P4O10(s) + 6 H2O(l) → 4 H3PO4(aq) ΔHorxn = -257.2 kJ a) Rewrite the thermochemical equation to include the enthalpy change as a term in the equation. b) How much energy is released from the reaction of 5.00 mol of P4O10 with excess water?

O THERMOCHEMISTRY Using Hess's Law to calculate net reaction enthalpy Lindsay Dimethyl ether, a useful organic solvent, is prepared in two steps. In the first step, carbon dioxide and hydrogen react to form methanol and water: CO,(g) + 3 H,(g) → CH;OH(1) + H,0(1) AH=-131. kJ In the second step, methanol reacts to form dimethyl ether and water: 2 CH,OH(1) → CH;OCH,(g) + H,0(1) AH=8. kJ Calculate the net change in enthalpy for the formation of one mole of dimethyl ether from carbon dioxide and hydrogen from these reactions. Round your answer to the nearest kJ. II

Calculate the heat of neutralization for limewater, Ca(OH):(aq), and hydrochloric acid, HCl: Ca(OH):(aq) + 2 HCl(aq) → CaCl:(aq) + 2 H¿O(1) AH° = ? using Hess's Law and the three thermochemical equations below. Show work. (1) СаО(s) + 2 HС(аq) > СаСl,(аq) + H.О(1) (2) СаО(s) + H:0(1) > Са(ОН):(s) (3) Са(ОН):(s) watery Ca(ОH):(аq) AH° = - 186 kJ AH° = - 62 kJ AH° = - 13 kJ

Rearrange the thermochemical equations given to determine the AH value for the equation of interest. Determine: 2 Fe203(s) + 3 C(s) → 3 CO2(g) + 4 Fe(s) Given Enthalpy (K/mol) 3 -833.8 O2(g) Fe203(s) 2 1. 2 Fe(s) + ch 2. C(s) + - O2(8) → CO(g) -110.4 1 O2(g) → CO2(g) -264.8 3. CO(g) + K/mol

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Acetylene, C2H2, is a gas commonly used in welding. It is formed in the reaction of calcium carbide, CaC2, with water. Given the thermochemical equations, calculate the value of AH'† for acetylene in units of kilojoules per mole. CaO(s) + H2O(1) → Ca(OH)2(s) AH°=-65.3 kJ 2CaO(s) + 5C(s) → 2CAC2(s) + CO2(g) AH°=+753 kJ CaCO3(s) → CaO(s) + CO2(g) AH° = +178 kJ CaC2(s) + 2H2O(1) → Ca(OH)2(s) + C2H2(g) AH°=-126 kJ C(s) + O2(3) → CO2(3) AH°=-393.5 kJ 2H20(1) → 2H2(g) + O2(g) AH°=+572 kJ i kJ/mol

When methanol, CH3OH,CH3OH, is burned in the presence of oxygen gas, O2,O2, a large amount of heat energy is released. For this reason, it is often used as a fuel in high performance racing cars. The combustion of methanol has the balanced, thermochemical equation CH3OH(g)+32O2(g)⟶CO2(g)+2H2O(l)ΔH=−764 kJCH3OH(g)+32O2(g)⟶CO2(g)+2H2O(l)ΔH=−764 kJ How much methanol, in grams, must be burned to produce 639 kJ639 kJ of heat?

（1）Consider the reaction: 2A (g) + 3 B (g) → 2 C (g)     ΔHrxn = +254.3 kJ What will be the enthalpy change (in kJ) if 0.471 mol B reacts in excess A?   （2）Consider the reaction: C (s) + O2 (g) → CO2 (g)     ΔHrxn = -393.5 kJ What mass of carbon (in g) must be reacted via this mechanism to release 581.2 kJ of heat?