College Chemistry Question

Question

Convert a pressure of 0.0248 mm Hg to the equivalent pressure in Pascals.

How in the world do i go about working this problem out? what even is Pascals to begin with ?

please if you can show how you worked this problem out i would be extremely grateful.

thank you.

Answer 1

Some dimensions of measurement have more than one accepted standard (for example, feet or meters to measure the length dimension). Pressure might be the one with the most standards: atmospheres (atm), pascals (Pa), torr (torr), millimeters mercury (mmHg), pounds per square inch (PSI), or newtons per square meter.

To convert between these units, it's helpful to know what "standard pressure" is in each one. For example, in atmospheres it's 1 (1atm), and in mmHg it's 760. In pascals it's 101325 Pa. (these are the most common three used in chemistry classes).

So we'll take our pressure, 0.0248 mmHg, and we'll multiply by a fraction with the same amount of pressure on top and bottom: 101325 Pa / 760 mmHg. Because the top and bottom of the fraction are the same amount of "stuff" (the same amount of pressure), it doesn't change our value. But because they are different units, it changes what units we're measuring that value in. I like to call this process "unit conversions," but in chemistry it's more likely called "stoichiometry."

so 0.0248 * 101325 / 760 = 3.31 Pa