How much energy is released during the combustion of 3.50moles of propane (C3H8 ΔH=−2220kJ/mol)

6) (a) calculate the absorbance of the solution if its concentration is 0.0278 m and its molar extinction coefficient is 35.9 l/(mol cm). the depth of the cell is 5 mm. (b) what is the %t? (7) calculate the absorbance of the solution if the transmitted light intensity is 70% of the initial light beam intensity

Stoichiometry- i need with 14 and 15! an explanation would be appreciated!

A0.10 m aqueous solution of sodium sulfate is a better conductor of electricity than a 0.10 m aqueous solution of sodium chloride. which of the following best explains this observation? (a) sodium sulfate is more soluble in water than sodium chloride. (b) sodium sulfate has a higher molar mass than sodium chloride. (c) to prepare a given volume of 0.10 m solution, the mass of sodium sulfate needed is more than twice the mass of sodium chloride needed. (d) more moles of ions are present in a given volume of 0.10 m sodium sulfate than in the same volume of 0.10 m sodium chloride. (e) the degree of dissociation of sodium sulfate in solution is significantly greater than that of sodium chloride.