[afchick7689]

I did parts 1 and 2, but the third part is confusing me-- should i be using Charles's Law? But I know that the volume is not changing, so is this incorrect? What math needs to be done here to calculate the temperature of the metal and the water??


Given a sheet of metal that is 1.2 cm wide, 3.8 cm long, and 1.0 mm thick with a density of 8.57 g/cc, calculate the mass of the metal.
M= D*V
1.0 mm |      1 m      | 100 cm = .1 cm
            | 1000 mm   | 1m
1.2 cm * 3.8 cm * 0.1 cm = .456 cm3 (or .456 cc)
M = 8.57 g/cc * .456 cc
M = 3.91g

The specific heat of the metal is 0.266 j/g-°C.  How much heat would be required to heat the metal from 25deg C to 100 deg C?
Heat required = Mass * Change in Temperature * Specific Heat
Heat required = 3.91 g * 75°C * 0.266 j/g-°C
Heat required = 78 joules (W/SIG FIGS: 80 joules)

**If the metal at 100 C were dropped into 8.5 g of water at 25C, what would be the final temperature of the metal and water?
V1 = V2
T1     T2

3.91 g + 8.5 g = 12.41g

3.91 = 12.41
100C     ?

[xiankai]

for part 2, u may want to round off to 3 sig fig because of the 3 sig fig present in the specific heat capacity

for part 3, its based on part 1 and part 2 i believe. u cant use charles' law as it is for a single, ideal gas, not two different substances. strange that the specific heat capacity of water wasnt given. are u expected to know that? because its instrumental in finding out the answer.

[afchick7689]

for part 2, though, the temperature given is 100 C, which only has 1 sig fig, which is why i left my answer with only one sig fig...

for part 3, i looked up the the specific heat of water and found it is 4.18 j/g C.  So i think i know the equation that i need to use for the third part, is it mDTCp(cold) = -mDTCp(hot) ? --
so i would plug in the values, except the one thing im confused about would be the change in temperature that I should put on both sides??

[xiankai]

let the change in temperature be (x - 25) for water and (100 - x) for the metal. where x is the final temperature of the metal and water.

solve for x.