what is more soluble in water ch3ch2oh or ch3(ch2)14oh?

Ethanol is more soluble in water.....

Ethanol is more soluble in water than the long-chain alcohol 1-pentadecanol which unlike ethanol is not miscible with water, but sits in a layer on top of water.

Ethanol is polar and so there are Keesom forces (dipole-dipole attraction) between the two. In addition, ethanol easily forms hydrogen bonds with water. Therefore, ethanol is miscible with water (will mix in all proportions). 1-pentadecanol exhibits strong London dispersion forces between the alcohol molecules and so the molecules are attracted to each other more than they are attracted to water. Therefore, 1-pentadecanol is not miscible with water.

Note: The strength of London dispersion forces is based on the polarizability of the molecule. The greater the number of electrons and the greater the area over which they are spread, the greater the polarizability and the stronger are the London dispersion forces. (A common misconception is that the strength of London dispersion forces is due to the molecular weight. That is only coincidental. In general, the greater the number of electrons, the greater the molar mass of the compound.)