posted by Akitsuke
1. How much ice at -10 degrees Celsius is required to cool a mixture of 0.1 kg ethyl alcohol and 0.1 kg water from 20 degrees Celsius to 0 degrees Celsius?
2. Find the heat produced by 1 KW heating element in one hour.
3. A 3g lead bullet at 30 degrees Celsius is fired at a speed of 240 m/s into a large block of ice at 0 degrees Celsius in which it becomes embedded. What quantity of ice melt?
1. Write an energy balance equation: Heat absorbed by heating (from -10) and melting X g of ice equals heat removed from the liquid water and alcohol as they is lowered to 0 C. Solve for the amount of melting ice, X
2. Watts is Joules per seond. Multiply 1000 W by the number of seconds
3. First compute the number of Joules of kinetic energy in the bullet. It will equal the heat available to melt, Q. Assume a final equilibrium of 0 C and write an equation saying that much Q lowers the temp of the lead to 0 C while melting X g of ice. X will be the only unknown in that equation. Solve for it.