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Please help me with lab caculation Specific Heat of a Quarter In this lab , will determine the specific heat of a coin (a quarter) . In lecture 15_2
Please help me with lab caculation
Specific Heat of a Quarter In this lab , will determine the specific heat of a coin (a quarter) . In lecture 15_2 we discussed finding the specific heat of a material by the method of mixtures. In this lab , will be "mixing" a hot quarter with cooler water. When using the method of mixtures the specific heat of the object that is hot to begin with is given by: In the above equation the subscript l refers to the hot quarter because that is the object that loses heat, and the subscript g refers to the water in the calorimeter because that is the substance that gains heat. Thus the variables have the following meanings: cl = specific heat of quarter dollar cg = specific heat of water ml = mass of quarter (*** make sure to measure the mass in units of grams!!) mg = mass of water in calorimeter Tl = initial temperature of the hot quarter (When doing this experiment it will be 100 oC (**make sure to measure all temperatures in degrees Celsius, NOT Fahrenheit!) Tg = initial temperature of water in calorimeter Tf = final temperature of mixture of water and quarter in calorimeter c_l=(c_g m_g (T_f-T_g ))/(m_l (T_l-T_f ) ) Equipment: · Quarter dollar · Calorimeter · Kitchen tongs OR needle nose pliers OR standard pliers · Scale (Measure in grams) · small pan · Thermometer (Make sure to measure in Celsius degrees, not Fahrenheit) Procedure Briefly: You will be heating your quarter in boiling water and then quickly placing it into a measured amount of water in your calorimeter. You will measure the final temperature after the quarter and water in the calorimeter have reached the same temperature. Once the water in your pan is boiling must finish of the steps quickly to get good data. You should read through the following detailed instructions before starting the experiment so you have an idea what all the steps are going to be. Here are more detailed instructions: 1. Take the heating coil out of your calorimeter. You will not be using it in this experiment. You will use it in a later experiment. You should have a little cap in place of the heating coil to place on the lid. 2. Get your thermometer ready to use. You will be placing it in the calorimeter through the hole provided. You should find a way to keep your thermometer from resting on the bottom of the calorimeter. A rubber band around the thermometer at the appropriate height, or a close pin will probably work. 3. Place 100 - 125 grams of water in your calorimeter. You will need to know the exact mass of water, so measure the mass of the calorimeter empty first, then add your water, and then measure the mass again. 4. Measure and record the temperature of the water in the calorimeter. (In Celsius) 5. Set the lid of the calorimeter, including the thermometer through it, off to the side until later. 6. Measure the mass of your quarter (In grams) 7. Get a small pot of water boiling on the stove. 8. After the water is boiling use tongs or pliers to hold the quarter, submerged in the boiling water, for about 15 -20 seconds. This should be more than enough time for the temperature of the quarter to rise to 100oC, the same temperature as the boiling water. 9. After holding the quarter in the boiling water for 15-20 seconds, quickly drop the quarter into the water in the calorimeter. (It is essential to do step quickly to obtain useful data. If you delay, the heat from the quarter will dissipate into the air) 10. Quickly put the lid on the calorimeter. 11. Move the stirring handle (see calorimeter image above) continuously up and down to make sure the water temperature is evenly distributed. 12. Watch the thermometer, and when it has reached its maximum record the value. This should only take a few seconds. Data As mentioned at the beginning of this handout, the subscript "g" refers to the water (that is the substance that gains energy), and subscript "l " refers to the quarter (that is the substance that loses energy). Fill in all of the following data. ml = ________ (grams) mg = _______ (this is the mass of the water in the calorimeter NOT INCLUDING THE CALORIMETER) Tg = ________( OC) The specific heat of water (cg ) is already known to be 1.00 cal/goC Since the quarter was held in boiling water you know that Tl is equal to 100oC Tf = ________ (This is the final equilibrium temperature of the mixture) Use the method of mixtures to find the specific heat of the quarter. Show your calculation. cl = ____________
