Cubic decimeter

Volume. The special name Hter (L) has been approved for the cubic decimeter, but its use is restricted to volumetric capacity, dry measure, and measure of fluids (both gases andUquids). 

The volume V is the space occupied by the system. It is usually expressed in cubic meters (m3) or cubic decimeters (dm3). A dm3 is the same volume as a liter (L), but dm3 is preferred to the liter because it is a part of the SI (Systeme International d Unites) system of units. 

As shown above, the SI unit for volume is the cubic meter (m3), but most chemists use the liter (L, which is equal to 1 cubic decimeter (dm3)) or milliliter (mL). Appendix A lists the SI base units and prefixes, as well as some English-SI equivalents. 

We always use Cj in moles per liter (or in moles per cubic decimeter or 1 kilomole/m for the SI purist) as the only unit of concentration. The subscript j always signifies species, while the subscript i always signifies reaction. We use j as the species designation and species A as the key reactant. For gases the natural concentration unit is partial pressure Pj, but we always convert this to concentration, Cj = Pj RT, before writing the mass-balance equations. Conversion X means the fiaction of this reactant that is consumed in the reactor, Ca = Cao( 1 — X), but we prefer to use C i rather than X and find the conversion after we have solved the equation in terms of G. We cannot use this unit of density of a species when the density of the fluid varies with conversion, but we prefer to do so whenever possible because the equations are simpler to write and solve. 

DEMAL SOLUTION, A solution which contains one gram-equivalent of solute per cubic decimeter of solution. It is slightly weaker than a normal solution, in the ratio of the magnitude of the liter to the cubic decimeter. 

A cubic meter equals 264.2 U.S. gallons, much too large a quantity for normal use in chemistry. As a result, smaller, more convenient measures are commonly employed. Both the cubic decimeter (1 dm3 = 0.001 m3), equal in size to the more familiar metric liter (L), and the cubic centimeter (1 cm3 = 0.001 dm3 = 10 6 m3), equal in size to the metric milliliter (mL), are particularly convenient. Slightly... 

FIGURE 1.5 A cubic meter is the volume of a cube 1 meter along each edge. Each cubic meter contains 1000 cubic decimeters (liters), and each cubic decimeter contains 1000 cubic centimeters (milliliters). 

What is the difference between a cubic decimeter (SI) and a liter (metric) ... 

In many chemical measurements one neither knows nor, at the time of measurement, wishes to know the exact composition of the matrix. To give an example, a metallurgical firm will receive ore shipments measured by mass in kilograms. Representative samples in the seller s and receiver s laboratories are measured for quality by the amount of substance of a specified metal element or compound per given mass of ore. It is unnecessary and far too complex to attempt amount-of-sub-stance measurements on all components of the bulk. In exactly the same way, a food laboratory might measure the amount of substance (say lead) in orange juice in milligrams per liter (per cubic decimeter). The charm of the SI system lies in a coherence, which makes it possible to express all measured quantities in a combination of base and derived units [9],... 

The concept of the liter was cast into doubt. Was it to be based on the weight of a standard volume of dense water as before, or was it to be an alternate name of the cubic decimeter ... 

Do not use italic type for the chemical concentration unit M (molar, moles per cubic decimeter, moles per liter) or the unit N (normal). Use italic type for the unit m (molal, moles per kilogram). Use a space between the number and these abbreviations, that is, on each side of these abbreviations. 

For gases and liquids the liter is a much more practical measure of volume, especially in concentration expressions, than the derived unit of cubic meter, m3. Usage therefore has established the liter (L) as an accepted named unit, even though cubic decimeter (dm3) is the correct SI designation. The only prefix to be used with liter is milli, that is milliliter (ml). The symbol L is used for liter to prevent confusion with the letter I and the number 1. 

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