How much is 0 atm in kPa?

Question

It'd be really helpful. Thanks!

Why am I asking this?

A motorist checked his tired at start of his trip and the tire gauge read 25 psi. A tire gauge read zero at 0 atm which corresponds to 14.7 psi. The temp was 21C. After few hours, he checked his tired and the gauge pressure was up to 31 psi. To what temperature had the air in the tires been heated?

Note: The tire gauge is faulty in this problem.

Answer 1

Everyone is correct in stating that 0atm is 0Kpa - but it has never been achieved. I wrote in "evacuated to 0 psi" as part of an experimental in my PhD dissertation and a humourous professor proclaimed that I "should not worry about my PhD, my Nobel Prize is assured" because of this.

Anyway, I think you will find the question should state "at atmospheric pressure" not "at 0 atm". Atmospheric pressure is 1atm.

You can then use th empirical relationship (Combined Gas Law) of PiVi/Ti = PfVf/Tf (Pi = initial pressure, Vi = initial volume, and Ti = initial temperature, the f = final).

Since the volume of the tire doesn't change (ignoring minor changes due to inflation) thus Vi = Vf and can be ignored above.

Pi = 39.7 psi (25+14.7 since it is a relative reading)
Ti = 21.0 deg C
Pf = 45.7.0 psi (31 + 14.7)
Tf = ?

In these questions, always convert Temperatures into K (Kelvin), K = deg C + 273.1

Ti = 21+273.1 = 294.1 K
Tf = ?

So plug, chug, rearrange, chug some more...

39.7/294.1 = 45.7/Tf
Tf = 45.7/(39.7/294.1)
Tf = 338.5K
Tf = 338.5-273.1 = 65.2 deg C

The tires had warmed up to 65.3 deg C (i.e., the rider must have been riding around).

Hope this helps
Dr Oz

Answer 2

Yes, 0 is 0 regardless of what units you use.

You might be interested to know that mankind has never been able to achive 0 atm (a perfect vacuum). Even in space, there is some "atmospheric" pressure due to gas molecules coming from earth and from the sun. We believe that deep space, maybe out beyond our solar system, is essentially a perfect vacuum, no atoms or molecules or, maybe even, subatomic particles. There would still be photons of light and electro-magnetic waves.

You should be able to find conversion factors for atmospheric pressure in atmospheres, mm Hg, bars, torr, psi, and Kpa.

good luck

Answer 3

The problem should state that the gage reads 0 at 1 atm (14.7 psi). (Actually, it reads 0 at whatever the current atmospheric pressure is. The gage reads out pressure difference, not absolute pressure.)
(273.12 + T) / (273.12 + 21) = (14.7+31) / (14.7 + 25)
273.12 + T = (294.12)(45.7) / (39.7)
T ≈ 338.57 - 273.12
T ≈ 65.45°C

Answer 4

zero is zero.therefore 0 atm is 0 kpa

Answer 5

still zero
no such number that 0 atm is 101.3 kPa

0 atm is ZERO kPa.

Answer 6

0 atm = - 101.3 kPa
i.e. complete vacuum