Manometer Diagram with Barometric Pressure?

[Jay J]

Homework Statement

In the above manometer, attached to a sample of gas, the difference in the height of the mercury levels is 30.0mm. The barometric pressure is 754.0mm Hg. What is the pressure of the gas sample in kiloPascals ?

( The above figure is not drawn to scale, but the relative heights of the right and left columns of mercury are correctly shown )

Enter a numeric answer only, no units.

Homework Equations

1)If The height of the mercury level at the gas side is higher. This means that P(atm) > P(gas), So Pgas = 754 - 30 = 724 mmHg.

2)If The height of the mercury level at the atmosphere side is higher. This means that P(atm) < P(gas), So Pgas = 754 + 30 = 780 mmHg.

The Attempt at a Solution

1 mmHg = 133.3 Pa
So:

724*133.3 = 96509.2

OR

780*133.3 = 103974

what did i do wrong ?

 

[Borek]

what did i do wrong ?

You have not decided which is the correct answer.

--
methods

 

[Blueshift5]

Your solution looks correct. You converted the units from mmHg to Pa, which is the correct conversion. The only thing to note is that the question asks for the pressure in kiloPascals (kPa), so your final answer should be in kPa rather than Pa. This can be achieved by dividing your answers by 1000, so the final answer would be either 96.5 kPa or 104.0 kPa, depending on which equation you used. Other than that, your solution is correct.