Question

today, the us penny is made of copper-coated zinc. devise a calorimetric experiment to test for the metal content in a collection of pennies. the specific heat of copper and zinc are known. using the physics for, chapter 11, figure out how to measure how much copper or how much zinc (fractionally) are in a penny. Note: once you know one, you know the other by process of elimination. Do not perform the calculations but set up the expression. You also can assume all pennies are identical.

Answer 1

measure the current temperature of the penny.

let the temperature be Ti degree celcius.

put the penny in hot water , let say at temperature T degree celcius, in a thermally insulated chamber.

if mass of the penny is m kg and the percentage of copper in it is x%,

then mass of copper=mc=x*0.01*m kg

mass of zinc=mz=(100-x)*0.01*m kg

wait for the system to come into equilibrium and then measure the temperature of the system

as there is no heat exchange with outside,

heat lost by water=heat gained by copper+heat gained by zinc

==>mass of water*specific heat of water*temperature difference=mass of copper*specific heat of copper*temperature difference+mass of zinc*specific heat of zinc*temperature difference

as all the values are known except the unknow quantity x, it can be calculated from the above equation.

that will give you the percentage of copper in the penny and percentage of zinc in penny.