25.0 mL of ethanol (density = 0.789 g/mL) initially at 4.2°C is mixed with 35.7 mL of water (density = 1.0 g/mL) initially at 25.3°C in an insulated beaker. Assuming that no heat is lost, what is the final temperature of the mixture?

Question

25.0 mL of ethanol (density = 0.789 g/mL) initially at 4.2°C is mixed with 35.7  mL of water (density = 1.0 g/mL) initially at 25.3°C in an insulated beaker. Assuming that no heat is lost, what is the final temperature of the mixture?

DrBob222 · Accepted Answer

[(mass EtOH x specific heat EtOH x (Tfinal-Tinitial)] + [(mass water x specific heat water x (Tfinal-Tinitial)] = 0

Find mass EtOH and mass water from the density.
mass = volume x density. Tf is the only unknown.