DAT Biology 2.2

what makes water an excellent solvent?

The dipoles of water break up polar or charged ionic molecules, making it dissolve substances

what is the amount of heat needed to raise the temperature of a substance called?

heat capacity

is water more dense as a liquid or solid? why?

more dense as liquid. because molecules can move freely compared to ice, where molecules are locked in a crystal lattice structure, leading to separated molecules and less overall water molecules inside.

normally, if you condense the molecules of a substance it becomes liquid into a solid by increasing the pressure, the density of a substance increase. in a phase diagram this has a positive slope. What’s the case with water?

water is less dense as a solid, so in order to increase density, water actually needs to increased in temperature to become liquid to be more dense. So in a phase diagram, it has an unusual negative slope.

how does cohesion and surface tension work in water?

cohesion: attraction between like molecules. water’s h-bonds allows it to have strong cohesion between each other.

surface tension: result of the strong cohesive forces

how does adhesion work in water?

when water is attracted to unlike substances (eg: wetting finger to easily flip a page)

water has high adhesion bc of it polarity and hydrogen bonds. it can attract a lot of other polar substances.

Water transport in plants

capillary action + transpiration

through cohesion and adhesion working together through hydrogen bonds

capillary action= the ability of a liquid to flow in narrow spaces without external forces like gravity. from root to surface

transpiration= water evaporation from leaves creating negative pressure that pulls water upward from roots to the surface.

cohesion allows water molecules to stick to each other as they go up and adhesion attracts water to the surfaces of the cell wall and water-conducting vessels inside the plant.

Transpiration is able to occur in a plant due to ____.

Cohesion and adhesion forces