J.R. S. answered 10/24/19
Ph.D. University Professor with 10+ years Tutoring Experience
To answer this, we need the specific heats for gold, aluminum and water. Looking them up, I find
gold = 0.13 J/g/deg
aluminum = 0.91 J/g/deg
water = 4.184 J/g/deg
q = mC∆T where q = heat, m = mass, C = specific heat and ∆T = change in temperature
Heat lost by the metal = heat gained by the water, or put into an equation, we have
mC∆T(metal) = mc∆T(water)
For GOLD:
(25 g)(0.13 J/g/deg)(100 - Tf) = (100 g)(4.184 J/g/deg)(Tf - 20)
325 - 3.25Tf = 418.4Tf - 8368
421.65Tf = 8693
Tf = 20.6 degrees
For ALUMINUM:
(25g)(0.91 J/g/deg)(100 - Tf) = (100 g)(4.184 J/g/deg)(Tf - 20)
2275 - 22.75Tf = 418.4Tf - 8368
441.15Tf = 10643
Tf = 24.1 degrees