a gold nugget and a silver nugget have a combined mass of 14.9g. The two nuggets are heated to 62C and dropped into 15.0mL of H2O at 23.5C. When thermal equilibrium is reached, the temperature of the H2O is 25.0C. Calculate the mass of each nugget. Denisty of H2O=0998g/mL Specific heat: Gold=0.128H.g/C; Silver 0.235J/gC;H2)=4.184J/gC.

Answer 1

mass Au + mass Ag = 14.9; therefore,
mass Au = (14.9-mass Ag) and you will substitute 14.9-mass Ag for mass Au in the below equation.

The general set up is
[mass Au x sp.h. Au x (Tfinal-Tinitial)] + [mass Ag x sp.h. Ag x (Tfinal-Tintial)] + [mass H2O x sp.h. H2O x (Tfinal-Tinitial)] = 0

You have Tfinal and Tinitial, specific heat Au and specific heat Ag and specific heat H2O; the only unknowns are mass Au and mass Ag. For mass Au substitute 14.9-mass Ag which leaves just one unknown, namely mass Ag. Solve for that, and using mass Au + mass Ag = 14.9 you can solve for the Au. The mass H2O is volume x density = ? (Note: when you substitute mass Au = 14.9-mass Ag in that one place, remember that sp.h. Au still goes in that slot)

Post your work if you get stuck.