Pheromones are a special type of compound secreted by the females of many insect species to attract the males for mating. one pheromone has the molecular formula c19h38o. normally, the amount of this pheromone secreted by a female insect is about 1.8 10-12 g. how many molecules are there in this quantity?

Molar mass of C is 12.01g/mol.
Molar mass of H is 1.01g/mol.
Molar mass of O is 16.00g/mol.

If we have 19 atoms of C, 38 atoms of H, and 1 atom of O, then we have:
19*12.01+38*1.01+1*16.00=282.57g/mol
282.57g/mol is the molar mass of the pheromone molecule.

Supposing that "1.8 10-12 g" is 1.8*10^(-12)g then, this quantity of pheromones, shoud be divided by the molar mass of the pheromone molecule:
1.8*10^(-12)/282.57g/mol=6.37*10^(-15)moles

Using now Avogadro's number of molecules in 1mol (6.02*10^(23)) it is possible to know how many molecules are there in this pheromone quantity.
6.02*10^(23)/6.37*10^(-15)=9.45*10^(37)molecules

So, in this quantity of the pheromone there are approximately 9.45*10^(37)molecules of it.

Pheromones are the hormones secreted by females to attract male species. The molecular formula of pheromone is also known as 2-nonadecannone. The pheromone secreted by females is usually 1.8 10 -12 grams. The number of molecules in this quantity will be .

Given that,

Molecular formula of pheromone is

Molar Mass of C = 12.01 g/molMolar Mass of H = 1.01 g/molMolar Mass of O = 16 g/mol

Also,

There are 19 molecules of Carbon or C, it will be = 19 X 12.01 = 228.19 g/mol

There are 38 molecules of Hydrogen or H, it will be = 38 X 1.01 = 38.38 g/mol

There are 1 molecule of Oxygen or O, it will be = 1 X 16 = 16 g/mol

Molecular mass of = 282.57 g/mol

Now, given that female produces 1.8 10-12 g of pheromones, then it will be:

The value of Avogadro's number of molecules in 1 mol is .

Therefore, the number of molecules in pheromone will be:

Thus, the number of molecules in will be .

To know more about pheromones, refer to the following link:

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C. a mature ovule of a plant.