Mastering Pressure: Converting Between atm, mmHg, and kPa Units

Introduction:

Converting units of pressure can be an unfortunate situation in chemistry, but it's a necessary skill to have. There are three commonly used units of pressure, atmospheres (ATM), millimeters of mercury (mmHg), and Pascals (Pa) or kiloPascals (kPa). In this article, we will go through each unit's conversion, including their use in various conversions.

I. Converting between atmospheres and millimeters of mercury:

ATM equals 760.0 mm Hg. Depending on the direction of the change, there will be a multiplication or division involved. For instance, if you want to convert 0.875 atm to mmHg, you have to multiply the atm value by 760.0 mmHg / atm value. The atm values will cancel, leaving mmHg. Similarly, in converting 745.0 mmHg to atm, you have to divide the mmHg value by 760.0 mmHg / atm value. The mmHg value will be canceled and the atm in the denominator of the denominator will move to the numerator.

II. Converting between atmospheres and kilopascals:

One ATM is equal to 101.325 kPa. Based on the direction of the change, there will be a multiplication or division involved. For instance, if you want to convert 0.955 atm to kPa, multiply the atm value by 101.325 kPa / atm value. The atm values will cancel, leaving kPa. Similarly, if you want to convert 98.35 kPa to atm, divide the kPa value by 101.325 kPa / atm value. The kPa values will be canceled, and the atm in the denominator of the denominator will move to the numerator.

III. Converting between millimeters of mercury and kilopascals.

Here, we will be using both 760.0 and 101.325 values and will depend on the conversion to determine their location. Say for example in converting 740.0 mmHg to kPa,

you have to multiply 101.325 kPa by 740.0 mmHg and then divide by 760.0 mmHg. Then the mmHg will cancel, leaving kPa as the unit on the answer. In converting 99.25 kPa to mmHg, you have to multiply 760.0 mmHg by 99.25 kPa and then divide by 101.325, leaving mmHg as the unit of the answer.

IV. Conversion of other units:

A student reads a barometer in the laboratory and finds the prevailing atmospheric pressure to be 720.0 mmHg. Express this pressure in atmospheres, kilopascals, torrs, pounds per square inch, and pascals. One ATM equals 101.325 kPa, 760.0 torr, 760 mmHg, 14.696 psi, 101,325 Pa. Therefore, it is 0.9474 atm, 95.99 kPa, 720.0 torr, and 13.92 psi, 9.599 x 104 Pa. It's worth noting that pounds per square inch is not used in scientific circles, but if your teacher insists on its use, be familiar with it.

Conclusion:

There you have it, the three different units of pressure in chemistry, their conversions, and their use in various conversions. Practice is key to mastering these conversions, so don't hesitate to practice more. With the right understanding of units of pressure, you'll be able to execute various calculations in chemistry with ease.