Thermodynamics physics help

[jbrookins3]

Homework Statement

a constant-volume gas thermometer has a pressure reading of 0.900 atm at -50.0ºC and a reading of 1.510 atm at 100.0ºC. What temperature is associated with: a) a pressure of 1.000 atm and b) 1.200 atm?

Homework Equations

The Attempt at a Solution

well I am not sure where to start i thought i should use PV=nRT and i could use a proportion PV/T=PV/T and with the V constant it would just be P/T=P/T but the 2 pressures and temps in the problem don't follow that

if i just knew what direction to go in i should be able to solve the problem

 

[Fewmet]

Homework Statement

a constant-volume gas thermometer has a pressure reading of 0.900 atm at -50.0ºC and a reading of 1.510 atm at 100.0ºC. What temperature is associated with: a) a pressure of 1.000 atm and b) 1.200 atm?

Homework Equations

The Attempt at a Solution

well I am not sure where to start i thought i should use PV=nRT and i could use a proportion PV/T=PV/T and with the V constant it would just be P/T=P/T but the 2 pressures and temps in the problem don't follow that

if i just knew what direction to go in i should be able to solve the problem

P/T=P/T is the right approach. The ideal gas laws always use temperatures in Kelvins. (That prevents you getting zeros in denominators or negative pressures and volumes). If you convert -50.0ºC and 100.0ºC to K, do you get consistent results?

 

[rock.freak667]

Since P/T = constant, you should be able to use either P/T value to get T at P = 1 atm.

 

[jbrookins3]

for part a:
if i convert the temp to K and use P/T=P/T with both initial p/t i get
.900/223=1.00/T t=247.78K or -25.72C

1.510/373=1.00/T T=247.02K or 25.98C

is the difference just do to some rounding in the initial 2 sets of pressures and temps?

 

[rock.freak667]

That is the most likely reason I'd say.

 

[Fewmet]

for part a:
if i convert the temp to K and use P/T=P/T with both initial p/t i get
.900/223=1.00/T t=247.78K or -25.72C

1.510/373=1.00/T T=247.02K or 25.98C

is the difference just do to some rounding in the initial 2 sets of pressures and temps?

If you follow the rules of significant figures, the two temperatures round to 248 K and 247.0K. Those convert to -25 C and -26.1 C. Given the interpretation that values are known within 1 of the final digit, those numbers are "the same".