The specific enthalpy of liquid n-hexane at 1 atm varies linearly with temperature and equals 25.8 kJ/kg at 30°C and 129.8 kJ/kg at 50°C. Determine the equation that relates ˆ H ( kJ / kg ) Hˆ(kJ/kg) to T(°C) and calculate the reference temperature on which the given enthalpies are based. Then derive an equation for ˆ U ( T ) ( kJ / kg ) Uˆ(T)(kJ/kg) at 1 atm. Calculate the heat transfer rate required to cool liquid n-hexane flowing at a rate of 20 kg/min from 60°C to 25°C at a constant pressure of 1 atm. Estimate the change in specific internal energy (kJ/kg) as the n-hexane is cooled at the given conditions.

The atomic radius of sodium is 186 pm and of chlorine is 100 pm. the ionic radius for na+ is 102 pm and for cl– is 181 pm. in going from na to cl in period 3, why does the atomic radius decrease while the ionic radius increases? a. the inner electrons in the sodium cation shield its valence electrons more effectively than the inner electrons in the chloride anion do. b. the inner electrons shield the valence electrons more effectively in the chlorine atom than in the chloride anion. c. the outermost electrons in chloride experience a smaller effective nuclear charge than those in the sodium cation do. d. the outermost electrons in chloride experience a larger effective nuclear charge than those in the sodium cation do. e. monatomic ions are bigger than the atoms from which they are formed.

How much energy is made when a pice of wood burns. how do you know

The tendency of water molecules to stick together is referred to as a) adhesion b) polarity c) cohesion d) transpiration e) evaporation