Question

this is the answer but i dont get why they put (45.8-Tf) instead of (Tf-45.8). shouldnt the format be (Tf-Ti)? like for the eqution on the other side of the = sign its (Tf-15.4) and its in the format of (Tf-Ti). help

A 32.5 g cube of aluminum initially at 45.8 Celsius is submerged into 105.3g of water at 15.4 Celsius. What is the final temperture of both substances at thermal equilibrium Best Answer Sharlene J answered this lets tf be the final temperature you write that the energy lost by Al is equal to the amount of Energy gained by water formula E=m*Cs* (tf-ti) E (AI) = 32.5*0.903"(tf-45) E(w) = 105.3*4.18*(tf-15.4) You write that E(AI) = - E(w) 32.5*0.903*(45-tf) = 105.3*4.18*(tf-15.4) 29.3475(45-tf) = 440.154(tf-15.4) 1321.8525 -29.3475tf =-6778.3716+440.154tf 8100.1685=469.5015tf tf=17.250

Answer 1

actually the head released by Alumunium will be absorbenty water, it means the magnitude of heat released will be equal to magnitude of heat absorbed. Now, since heat released will be in negative, it we use (1f-45) the left amount of heat will be in negative while right mout of heat will be positive. so we will be comparing heat released and absorbed with sign belt we have to compare heat only the magnitud of heat so making the value of heat releaked, positive we are using (45-1f) instead of (Tf-45) or you could have written like 32.5x0.903 XT 105-3x 4.18 (Tf - 15:4) mod