Lake Erie contains roughly 4.00 1011 m3 of water.

(a) How much energy is required to raise the temperature of that volume of water from 9.0°C to 11.0°C?
J

(b) How many years would it take to supply this amount of energy by using the 1250-MW exhaust energy of an electric power plant?
yr

1 answer

For water, density is ρ =1000 kg/m ³,
V =4•10¹¹ m³ => m=ρ•V=1000•4•10¹¹ =4•10¹⁴ kg,
c =4183 J/kg•K, ΔT=11-9 =2 K.
E=Q= m•c• (T₁-T)= m•c• ΔT =4•10¹¹•4183•2=3.3464•10¹⁸ s
(b) E=P•t
t=E/P=3.3464•10¹⁸/1250•10⁶=2.677•10⁹ s=2.677•10⁹/365•24•3600=84.9 years.