BIOL 141 - Water Properties

Flashcards covering the essential properties of water, its role as a solvent, its states, and related concepts like pH and hydrogen bonding.

What percentage of the human body is comprised of water?

60-70%

Many of the special properties of water are due to what two factors?

Its polarity and/or hydrogen bonds.

What is the ability to dissolve a substance called?

A solvent.

Why does water act as a solvent?

Because it is composed of polar molecules.

In water, which element is slightly more electronegative: oxygen or hydrogen?

Oxygen.

What are molecules that are 'water loving' and can dissolve in water called?

Hydrophilic molecules.

When water surrounds a particle to dissolve it, what is formed?

A sphere of hydration.

What are non-polar compounds called that do not interact with water?

Hydrophobic.

What principle explains why non-polar molecules only dissolve in non-polar solvents?

'Like dissolves like'.

Why is soap considered amphipathic?

Because it can bridge the barrier between hydrophobic and hydrophilic substances.

In liquid water, what do hydrogen bonds constantly do?

Break and reform.

When water freezes, what type of structure do hydrogen bonds form?

A crystalline structure.

Why does ice float in liquid water?

Because its crystalline structure is less dense than liquid water.

Why does an object float better in saltwater?

Due to the increased density of the water caused by dissolved salt.

What property of water, the highest of any liquid, means it takes a long time to heat and cool?

Specific heat capacity.

What is the amount of heat one gram of a substance must absorb to change its temperature by one degree Celsius called?

Specific heat capacity.

What is the amount of energy required to change one gram of a liquid to a gas called?

The heat of vaporization.

How does the evaporation of sweat allow us to cool down?

Because the breaking of hydrogen bonds requires energy.

What property describes water molecules being attracted to each other through hydrogen bonds?

Cohesion.

What property, caused by cohesion, explains why denser objects can float on water?

Surface tension.

What property of water means it is attracted to other molecules, not just itself?

Adhesion.

When a hydrogen atom shifts between water molecules and leaves its electron behind, how is it transferred?

As a proton.

What does a molecule that lost a proton become?

A hydroxide ion.

What is a substance that increases the H+ concentration of a solution called?

An acid.

Solutions with pH values less than 7 are considered what?

Acidic.

Most biological fluids have pH values within what range?

6 to 8.