$$ \begin{aligned} &\text { Fill in the table below with the missing information: }\\\ &\begin{array}{|c|c|c|c|} \hline & \text { torr } & \text { in. Hg } & \text { kilopascals (kPa) } \\ \hline \text { (a) } & & 30.2 & \\ \hline \text { (b) } & 752 & & \\ \hline \text { (c) } & & & 99.3 \\ \hline \end{array} \end{aligned} $$

Pressure measurement is a fundamental concept in chemistry that involves determining the force applied by a fluid (liquid or gas) per unit area. The units of pressure are diverse, with several different measurements used across various fields of study and geographical regions. One common unit is the pascal (Pa), which is the SI unit for pressure and is defined as one newton per square meter.
In atmospheric chemistry, other units such as millimeters of mercury (mm Hg), inches of mercury (in. Hg), and torr are frequently used. The torr, named after Evangelista Torricelli, is particularly interesting as it is approximately equal to the pressure exerted by a millimeter of mercury. This is where one of the most essential conversions comes in - the relationship between torr and another pressure unit, the kilopascal (kPa). Being able to convert between these units is critical for scientists and students alike in order to accurately measure and communicate results.
Understanding pressure measurements and their conversions requires familiarity with the constants that relate these units. For example, knowing that 760 mm Hg (or 760 torr) is equal to 101.325 kPa allows chemists to easily compare and convert measurements taken in different units. This is particularly useful when calibrating instruments or when dealing with international data, as it ensures consistency in the representation of pressure values.

When working with pressure units in chemistry, converting from torr to kilopascals (kPa) is a task that often arises. As previously mentioned, the key to understanding this conversion lies in being aware of the constants that relate these two units. We know that 760 torr equals 101.325 kPa. From this relationship, it's possible to derive a conversion factor.
To convert torr to kPa, you can use the following equation:
\[ \text{kPa} = \left(\frac{\text{torr}}{760}\right) \times 101.325 \]
This formula is based on the proportion between the two values. When you know the pressure in torr, you simply divide by 760, then multiply the result by 101.325 to obtain the equivalent pressure in kilopascals. It's important when performing these conversions to pay attention to significant figures and rounding to ensure accuracy, since the precision of your conversion can impact the interpretation of your results.

Converting inches of mercury (in. Hg) to torr is another common task when dealing with pressure units. This conversion is relatively straightforward because 1 inch of mercury is defined as the pressure exerted by a 1-inch high column of mercury. Since 1 torr is the pressure exerted by a millimeter of mercury, and there are 25.4 millimeters in an inch, the conversion from inches of mercury to torr uses the factor of 25.4.
To convert in. Hg to torr, the equation is as follows:
\[ \text{torr} = \text{in. Hg} \times 25.4 \]
This direct proportionality simplifies the conversion process and highlights the interconnectedness of different units of pressure. Knowing how to convert between in. Hg and torr can be particularly useful for students and professionals who encounter meteorological data or work with vacuum systems where these units are commonly used.
It's essential to emphasize that accuracy in these conversions is crucial, as small discrepancies can lead to significant errors in calculations. For those working in fields that require precise measurements, such as pharmacology or environmental science, having a firm grasp of these unit conversions is indispensable.