The quantity of heat Q that changes the temperature ΔT of a mass m of a substance is given by Q=mcΔT, where c is the specific heat capacity of the substance. For example, for H2O, c=1cal/g∘C. And for a change of phase the quantity of heat Q that changes the phase of a mass m is Q=mL, where L is the heat of fusion or heat of vaporization of the substance. For example, for H2O the heat of fusion is 80 cal/g or 80 kcal/kg, and the heat of vaporization is 540 cal/g or 540 kcal/kg. Use these relationships to determine the number of calories to change (a) 1 kg of 0°C ice to 1 kg 0°C ice water; (b) 1 kg of 0°C ice water to 1 kg 100°C boiling water; (c) 1 kg of 100°C boiling water to 1 kg 100°C steam; and (d) 1 kg of 0°C ice to 1 kg 100°C steam.

When applying kirchhoff's rules, one of the essential steps is to mark each resistor with plus and minus signs to label how the electric potential changes from one end of the resistor to the other. the circuit in the drawing contains four resistors, each marked with the associated plus and minus signs. however, one resistor is marked incorrectly. which one is it?

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects