Parts per million by mass

C12-0107. The table lists the parts per million by mass of the principal ions in seawater ... 

The minimum mass concentration of oxygen required for fish life is 4 mg-L-1. (a) Assuming the density of lake water to be 1.00 g-mL 1, express this concentration in parts per million by mass, mg-kg L (b) What is the minimum partial pressure of 02 that would supply the minimum mass concentration of oxygen in water in order to support fish life at 20°C (see Table 8.5) (c) What is the minimum atmospheric pressure that would give this partial pressure, assuming that oxygen exerts about 21% of the atmospheric pressure ... 

Solution (a) Finding parts per million by mass of Ca. Combining the steps, we have... 

Sulfur is present in the Garth s crust at a mixing ratio of less than 500 parts per million by mass and in the Earth s atmosphere at a total volume mixing ratio of less than 1 ppm. Yet, sulfur-containing compounds exert a profound influence on the chemistry of the atmosphere and on climate. 

Solubility is expressed in this table as parts per million by mass, i.e.,... 

This table gives the estimated abundance of the elements in the continental crust (in mg/kg, equivalent to parts per million by mass) and in seawater near the surface (in mg/L). Values represent the median of reported measurements. The concentrations of the less abundant elements may vary with location by several orders of magnitude. 

The concentration of hydrogen in a metal is expressed as parts per million by mass (ppm). In weld metal it is the convention to use the expression millilitres of hydrogen at standard temperature and pressure (STP) per one hundred grams of deposited (or fused) metal (mL/lOOg). 

In addition to the mole fraction, molality, and concentration, the composition of a solution can be represented by the mass percentage, by parts per million by mass, or by volume percentage. For dilute solutions, Henry s law can be expressed in terms of any of these composition measures, since all of them are proportional to the mole fraction in a dilute solution. 

In the chemical and environmental engineering literature and in this book, ppm applied to a gas always means parts per million by volume or by mol. These are identical for an ideal gas, and practically identical for most common gases at 1 atm pressure. Ppm applied to a liquid or solid almost always means parts per million by mass. 

This test method covers the determination of traces of carbonyl sulfide (COS) in propylene. It is applicable to COS concentrations from 0.5 to 4.0 mg/kg (parts per million by mass). See Note 1. 

An analysis was done on a rock sample to determine its rubidium content. The rubidium content of a portion of rock weighing 0.350 g was extracted, and to the extracted sample was added an additional 29.45 ixg of Rb. The mass spectrum of this spiked sample showed a Rb peak that was 1.12 times as high as the peak for Rb. Assuming that the two isotopes react identically, what is the Rb content of the rock (expressed in parts per million by mass) The isotopic abundances and isotopic masses are shown in the table. 

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