Question

Liquid sodium is being considered as an enegine coolant. How many gramd of liquid sodium (minimum) are needed to absorb 3.80 MJ of energy in the form of heat if the temperature of the sodium is not to increase by more than 10.0 C? Use Cp= 30.8 J/(K • mol) for Na(I) at 500 K.

mass of Na(I): _______ g

Answer 1

When looking at absorbance of heat from a substance in a single phase We need to use the formula q=nCOT where q = The heat absorbed or released from the substance. n = number of moles of substance ce The specificheat of the substance GT a The Change in temperature of the substance. * Reananging to find mass of liquid sodium, we can plug in the numbers make sure the units cancel out to leave only grams, then calculate. * Sodium ip 22-998(mol, a 10°C temperature change is the same as a temperature change, and a MegaJig a million Jonces = 186J. - na q/(ex oT) = (3.8*1868) (30.85/mol-k) x 10k a na 1.23x18t moles of Na. Convert moles to grams of Na for mass (w): weight (W) 7 1.23 X204 = 22.99 - mole (n) = morint. gwa (1.23x104}x 22.99 W = 2.8*10 grams of Na. Mass of Sodium = 2.83x105 g