Name_____________________________________________ Date__________________ Period_____ SPS7. Students will relate transformations and flow of energy within a system. c. Determine the heat capacity of a substance using mass, specific heat, and temperature. You have probably noticed that a metal spoon heats up quickly when placed in a cup of soap while a plastic spoon heats more slowly. The difference between the final temperatures of the two spoons depends on whether they are good conductors or good insulators. (The metal spoon heats up quickly, making it a good conductor. The plastic spoon does not, making it a good insulator.) But what makes a substance a good or poor conductor depends on the amount of energy that can be absorbed before the substance experiences a temperature change. This is called specific heat. Specific heat is the amount of energy that can be transferred as heat that will raise the temperature of 1 kg of a substance by 1°C. Imagine that you are at the pool on a hot summer day. Think of how the water in the pool feels against your skin. Now imagine getting out of the pool and stepping on the concrete. How didthe water feel? How did the concrete feel? Which absorbed more energy without a change in temperature? Water has a higher specific heat than concrete which means it requires more energy to change the temperature of water. Specific Heat Equation Energy= (mass) x (specific heat) x (temperature change) Q= mcΔT Q is energy and is measured in joules. m is mass and is measured in kilograms. c is specific heat and is measured in J/kg ·°C ΔT is change in temperature (final temp- initial temp) Specific heat is the heat needed to raise the temperature of 1 gram of material by 1°C. Practice Problems 1. How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the water’s temperature from 25°C to 37ºC? 2. How much energy is needed to increase the temperature of 755 g of iron from 283°C to 403°C? 3. Aluminum has a specific heat of 0.902 J/g x oC. How much heat is lost when a piece of aluminum with a mass of 23.984 g cools from a temperature of 415.0 oC to a temperature of 22.0 oC? 4. How much heat is needed to raise the temperature of 100.0 g of water by 85.0°C? 5. How much heat is absorbed by a 750-g iron skillet when its temperature rises from 25°C to 125°C? 6. In setting up an aquarium, the heater transfers 1200 kJ of heat to 75,000 g of water. What is the increase in the water's temperature? (Hint: Rearrange the specific heat formula to solve for ΔT.) 7. To release a diamond from its setting, a jeweler heats a 10.0-g silver ring by adding 23.5 J of heat. How much does the temperature of the silver increase? 8. What mass of water will change its temperature by 3.0°C when 525 J of heat is added to it?