Jelly bean example

In addition to explaining verbally the concepts of mass spectrometry, it is also helpful to explain them visually. Two ideas utilized in newborn screening, for example, is the ability of a mass spectrometer to sort molecules by their mass and determine how many of these compounds are present. One illustration uses coins while another uses jelly beans. Instructions on how to prepare and present these experiments are shown below. 

Figure 14.5. An illustration of how a mass spectrometer measures compounds in blood by using reference standards (Stable Isotopes) using the example of jelly beans. (See color insert.)...

In reality, jelly beans are not identical. For example, let s assume that you weigh 10 beans individually and get the following results ... 

Let s look at the relationship between mass and number of components more closely by using our candy example. The individual candies have the masses 15 g (mints) and 5 g (jelly beans). Consider several cases. 

Just as you could not make a direct conversion from the mass of jelly beans to the number of jelly beans, you cannot make a direct conversion from the mass of a substance to the number of representative particles of that substance. You must first convert mass to moles by multiplying by a conversion factor that relates moles and mass. That conversion factor is the molar mass. The number of moles must then be multiplied by a conversion factor that relates the number of representative particles to moles. For this conversion, you use will use Avogadros number. This two-step process is shown in Example Problem 10.4. 

A nonhomogeneous mixture may differ in composition in various places in the mixture, whereas a solution (a homogeneous mixture) has the same composition throughout. Examples of nonhomogeneous mixtures include spaghetti sauce, a jar of jelly beans, and a mixture of salt and sugar. 

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