# Physics question, stuck

1. Jun 21, 2004

### winston0064

Problem: A glass vial containing a .016kg sample of an enzyme is cooled in an ice bath. The bath contains water and .12kg of ice. The sample has specific heat capacity 2250 J/kg k; the glass vial has mass .006kg and specific heat capacity 2800 J/kg K. How much ice melts in cooling the enzyme sample from 19.5 C to the temp of the ice bath?

My work thus far: (initial approach may be what I am finding trouble with...)

Qh2o = .12kg (4190J/kg K)(19.6 - 0 C)
Qenz = .016(2250)(19.6 - 0 C )
Qvial = .006(2800)(19.6 - 0 C)
I believe this problem may involve latent heat but I am stuck as to where to go from here to find the mass of the ice that melted. Any help would would be much appreciated.

2. Jun 21, 2004

### HallsofIvy

Staff Emeritus
You have already calculated the total heat the various things must lose in order to go down to 0 degrees. Yes, you need the "latent heat of melting" (which is exactly the same as the "latent heat of freezing"!). That should be given as the heat required to melt 1 kg of ice. Divide the total heat by that to find out how many kg of ice it can melt.