Question

Se incalzesc 150 g de apa de la temperatura t1 la temperatura t2= 90 C. utilizand 43,89 kJ.. Determinati valoarea temperaturii initiale a apei exprimata in kelvin. Se considera ca nu au loc pierderi de caldura .

Answer 1

m H2O = 150g = 0,15 Kg
t1 = ?°C
t2 = 90°C
Q = 43,89 KJ

CH2O= 4,18Kj/kg*gr

Q = m*CH2O*∆t <=> 43,89 = 0,15*4,18*(t2-t1 <=> 43,89 = 0,627(90-t1) <=> 43,89 = 56,43-0,627t1 => 0,627t1 = 56,43-43,89 <=> 0,627t1 = 12,54 => t1 = 20°C

T(°K) = 273+t°C = 273+20 = 293 K