Which has more molecules, a teaspoon of water that has a mass of 1.25 grams or a teaspoon of ethanol - C 2 H 5 OH that has a mass of 0.890 grams?

Water has more molecules.

Explanation:

The number of molecules in each compound can be calculated by using the formula,

Number of moles (n) = Mass (M) / Molecular weight of compound (M. wt)

Given,

Mass of Water = 1.25 grams,

Mass of Ethanol = 0.890 grams,

We know calculate the molecular weight of Water and Ethanol

SInce, Molecular formula of water is H₂O.

Atomic mass of Hydrogen = 1

Atomic mass of Oxygen = 16

Therefore Molecular weight of Water = 2 (1) + 16 = 18.

SInce, Molecular formula of Ethanol is C₂H₅OH.

Atomic mass of carbon is = 12

Atomic mass of Hydrogen = 1

Atomic mass of Oxygen = 16

Therefore, Molecular weight of Ethanol = 2 (12) + 5 (1) + (16) + (1) = 46.

Now, number of moles or molecules of water (n) = 1.25/18

By solving we get number of moles or molecules of water (n) = 0.06944 molecules.

Now, number of moles or molecules of Ethanol (n) = 0.890/46

By solving we get number of moles or molecules of Ethanol (n) = 0.06944 molecules. n = 0.01934.

By observation of both 'n' values we can know that water has more molecules.