The word mole usually pops up in the news when it comes to a hairy creature underground, a police infiltrator and sometimes a semitone lower in a piece of music. The chemical mole is used to determine whether or not someone is a peak loader. What exactly is this unit?
A peak loader is a company from which more than 2500 mol of nitrogen ends up in a nitrogen-sensitive Natura 2000 area within a radius of 25 kilometers. Cow emissions are often calculated in kilograms. Why is the definition of a peak load expressed in moles?
“You can express the amount of nitrogen in both moles and kilograms,” says nitrogen specialist Wim van der Maas of the National Institute for Public Health and the Environment (RIVM). He is the lead author of the report that was released on Monday in which RIVM, commissioned by the Ministry of Agriculture, Nature and Food Quality (LNV), advises on the threshold value for determining what a peak load is.
Add different molecules
“In the past, the Ministry of Agriculture chose to use moles as a measurement unit for nitrogen. Mol has the advantage that it is easier to add up different molecules than when you use kilograms. Moreover, you can avoid confusion because a kilogram of ammonia contains much more nitrogen than a kilogram of nitrogen dioxide.”
Mole is used in chemistry to measure the number of particles, or molecules, of a particular substance. Since molecules are very small, the measure mole is used here, where 1 mole is equal to a six with 23 zeros. That large number therefore represents the number of molecules, for example ammonia, that are contained in 1 mole.
A molecule is a compound of atoms, which are smaller units. When it comes to the threshold value of 2500 mol of nitrogen, then it is not about pure nitrogen but about 2500 molecules consisting of a connection of the atom of nitrogen with another atom such as hydrogen in the case of the molecule of ammonia or with oxygen in the case of nitrogen dioxide. Each molecule has a different weight. For example, 1 mole of nitrogen is 14 grams, 1 mole of ammonia is 17 grams and 1 mole of nitrogen dioxide is 46 grams.
Threshold value
“Because the weight of nitrogen dioxide mainly consists of dioxide, there is much less nitrogen in a kilogram of nitrogen dioxide than in a kilogram of ammonia.” On behalf of LNV, RIVM has investigated which three thousand companies emit the most nitrogen, or rather nitrogen compounds, in the Netherlands. This is how the threshold value of 2500 mol was established. If they stuck to six hundred peak loaders as Johan Remkes proposed at the end of last year, that value would have been a lot higher.
The ratio between ammonia and other nitrogen compounds within the threshold value of 2500 mol is not the same at every company. For example, the share of ammonia is the largest at most livestock farms. This also applies to two industrial companies, namely cocoa producer Olam Cocoa in the Zaan region and insulation producer Rockwool in Roermond. The remaining 23 industrial companies mainly produce nitrogen dioxide.
“Putting these different molecules next to each other is sometimes like comparing apples and oranges, but with moles it is easier to add up apples and pears than with kilos because you then have to convert each molecule to its individual weight before you calculate it. total weight of a given deposition.”