A piece of an unknown substance weighing 124.0 grams is heated in boiling water to 100.0oc. when the substance is placed in a calorimeter containing 300.0 grams of water, the temperature of the water increased from 20.0oc to 26.0oc. what is the specific heat of the unknown substance, assuming all the heat is transferred to the water?

The heat cause 300g water temperature increase from 20 to 26 celcius. The heat transferred would be: 300g * (26 °C - 20 °C) * 4.2 joule/gram °C = 7560J

The unknown substance is added to the water, so its final temperature should be the same as the water. The calculation would be:

7560J = 124g * (100-26) * specific heat

specific heat = 7560J / 124g / 74 °C = 0.8238 J/gram °C