Measuring the temperature of very cold substances can be challenging. Here is one way to measure the temperature of liquid nitrogen. A 50-g flake of aluminum is submerged in liquid nitrogen and left i

Measuring the temperature of very cold substances can be challenging. Here is one way to measure the temperature of liquid nitrogen. A 50-g flake of aluminum is submerged in liquid nitrogen and left immersed until it is in thermal equilibrium. The flake is then removed and placed in a well-insulated container with 490 ml of water at 30°C. When water and flake attain thermal equilibrium, the temperature of the water is found to be 25°C. What was the temperature of the liquid nitrogen?