Estimate the melting point of an unknown substance in deg C if the latent heat of fusion of the substance is 6.42 kJ/mol and the entropy change for the change in state of the substance from solid to liquid at its melting point is 26.40 J/K mol.

Calculate ∆H for the reaction CH4(g) + ½ O2(g) → CO(g) + 2 H2(g) given the following data:   Equation ∆H (kJ) CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) -802 CH4(g) + CO2(g) → 2 CO(g) + 2 H2(g) 247 CH4(g) + H2O(g) → CO(g) + 3 H2(g) 206

For a particular chemical reaction H = 6.8 kJ and S = –29 J/K. Under what temperature condition is the reaction spontaneous?

A certain hydrocarbon of the molecular formula CxH2x has a standard enthalpy of formation ∆Hf° = –115.0 kJ/mol and a standard enthalpy of combustion ∆H°combust = –3281.5 kJ/mol. What is x? Use the following data: ∆Hf°[CO2(g)] = –393.5 kJ/mol, ∆Hf°[H2O(l)] = –285.8 kJ/mol.   A.  x = 7   B.  x = 4   C.  x = 5   D.  x = 6   E.  x = 8

Use the values of ΔHof  to calculate the ΔHo for the following reaction: 4 AB3(g) +  5 C2(g) → 4 AC(g) + 6 B2C(g) Substance ΔHof in kJ/mol AB3(g) 55.8 C2(g) 0 AC(g) 200.5 B2C(g) -65.5

Consider the following reaction: CaCO 3(s) <—> CaO (g) +CO 2(g) For this reaction, delta S = +158.9 J/ mol and Delta * H ^ o = + 177.9kJ / (mol) . These values are fairly constant with changes in temperature. Over what specific temperature range is this reaction spontaneous in the forward direction?

Determine the total entropy change when 15.00 g of ice at –15°C is heated to 75°C. The molar heat of fusion of ice is 6.02 kJ/mol, and its specific heat is 2.11 J/g °C. The specific heat of water is 4.184 J/g °C