Which describes the enthalpy change associated with an endothermic reaction? a) it is negative because the enthalpy of the products is greater than the enthalpy of the reactants. b) it is positive because the enthalpy of the products is greater than the enthalpy of the reactants. c) it is negative because the enthalpy of the reactants is greater than the enthalpy of the products. d) it is positive because the enthalpy of the reactants is greater than the enthalpy of the products.

When 225mg of anthracene, c14h10(s), was burned in a bomb calorimeter the temperature rose by 1.75k. calculate the calorimeter constant. by how much will the temperature rise when 125mg of phenol, c6h5oh(s), is burned in the calorimeter under the same conditions? (δch< (c14h10,s)=–7061 kj mol−1.)

What reaction is taking place? 02 + c3h8 = h20 + co2

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.