If the molecular weight of air is 28.9, what is the density of air at atmospheric pressure and a temperature of 354.5 k? 1 atm = 1.013 × 105 n/m2 , the mass of a proton is 1.67262 × 10−27 kg , avogadro’s number is 6.02214 × 1023 mol−1 and k = 1.38065 × 10−23 n · m/k . answer in units of kg/m3

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.