CHEMISTRY COMMUNITY

In 1750, Joseph Black performed an experiment that eventually led to the discovery of enthalpies of fusion. He placed two samples of water, each of mass 150. g, at 0.00 degreesC (one ice and one liquid) in a room kept at a constant temperature of 5.00 degreesC. He then observed how long it took for each sample to reach its final temperature. The liquid sample reached 5.00 degreesC after 30.0 min. However, the ice took 10.5 h to reach 5.00 degreesC. He concluded that the difference in time that the two samples required to reach the same final temperature represented the difference in heat required to raise the temperatures of the samples. Use Black’s data to calculate the enthalpy of fusion of ice in kilojoules per mole. Use the known heat capacity of liquid water.

The solutions manual states that because both the water and ice samples started at 0 degreesC and the water sample took .5 hr to reach 5.00 degreesC, then the ice took 10.0hr to melt. Where do you get the 10.0 hours from?

It's mentioned that the ice took 10.5 (10 hours and 30 minutes) hours to reach 5.00 degrees. If it takes 30 minutes for water to increase five degrees in temperature, it's safe to say that the ice took ten hours to melt, and as water also took thirty minutes to reach 5.00 degrees.