When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH°f) of NaF(s)?

When a 3.00 g sample of RbBr is dissolved in water in a calorimeter that has a total heat capacity of 0.903 kJ⋅K−1, the temperature decreases by 0.440 K. Calculate the molar heat of solution of RbBr.

[2] When 1.045 g of CaO is added to 50.0 ml of water at 22.0 °C in a coffee-cup calorimeter, the temperature of the water increases to 29.3 °C. Assume that the specific heat and density of the solution is 4.184 J/g-°C and 1.00g/ml, respectively. The heat capacity of the calorimeter is 18.0 J/°C. Calculate AH for the reaction. CaO(s) + H2O(1) –→ Ca(OH)2(aq); AH =

How many moles of butane, C4H10(l), must be burned to produce 234 kJ of heat under standard state conditions? (The heat of combustion for butane is −2855.7 kJ/mol.)

Consider the following reaction: 2Mg(s)+O2(g)⟶2MgO(s)ΔH∘=−1203kJ What mass of magnesium must be combusted in order to generate 174.0 kJ of heat?

What is the enthalpy of reaction, ΔHrxn for the reaction of nitrogen gas with oxygen gas to produce NO2(g), based on the following information? These reactions are not at standard state or at 298 K. N2(g) + O2(g) → 2 NO(g); ΔH = 332.9 kJ2 NO2(g) → 2 NO(g) + O2(g); ΔH = 718.4 kJ Report your answer in kJ to 1 decimal place.

（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?

Given the standard enthalpy changes for the following two reactions: (1) 2Pb(s) + O₂(g) → 2PbO(s) (2) 2Zn(s) + O₂(g) → 2ZnO(s) Standard enthalpy change = AH-434.6 kJ AH° -696.6 kJ What is the standard enthalpy change for the following reaction? (3) PbO(s) + Zn(s) → Pb(s) + ZnO(s) AH° = ? KJ =