Chemical Composition and Cellular Role of Water

Flashcards covering the cellular transport functions, molecular composition, atomic masses, mass percentages, and chemical formation equation of water.

Plasma membrane (cellular membrane)

The membrane surrounding each cell in living organisms through which water passes, transporting necessary substances into the cell and carrying wastes out of the cell.

Water molecule

A molecule composed of the union of two hydrogen atoms with one oxygen atom.

Mass percentage of hydrogen in water

$11.11\%$ of the total mass of a water molecule.

Mass percentage of oxygen in water

$88.89\%$ of the total mass of a water molecule.

Mass ratio of hydrogen to oxygen in water

$1 : 8$, where $4\,\text{g}$ of hydrogen react completely with $32\,\text{g}$ of oxygen.

Chemical equation for water formation

$$2H_2 + O_2 \rightarrow 2H_2O$$