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## Homework Statement

A constant-volume gas thermometer is cal-

ibrated in dry ice (which is carbon dioxide

in the solid state and has a temperature of

−80◦C) and in boiling ethyl alcohol (78◦C).

The two pressures are 1 atm and 1.542 atm.

What value of absolute zero does the cali-

bration yield?

Answer in units of ◦C.

003 (part 2 of 2) 10.0 points

What is the pressure at the boiling point of

water?

Answer in units of atm.

## Homework Equations

y-y

_{1}=m(x-x

_{1})

m = dy/dx

## The Attempt at a Solution

pt 1.

(-80C,1.0atm)

(78C,1.542atm)

m = (1.542-1.0)/(78-(-80)) = .0034

y-1.542 = .0034(x-78)

y-1.542 = .0034x -.2652

y = .0034x + 1.2768

if we assume temp v. pressure is linear.. and according to the text this is a good assumption

so i put the pressure equal to zero at absolute zero

0 = .0034x +1.2768

-1.2768 = .0034x

x = -1.2768/.0034 = -375.5294 C

this is wrong according to the homework program

but!... I got the second half right using that equation

boiling point of water in C is 100C so..

y=.0034(100) +1.2768 = 1.6168 atm

and this leads me to believe that my equation is correct.. what am i doing wrong?