5 Written Questions
5 Matching Questions
- Describe how and why hydrogen bonds form in water.
- Why is water in the solid phase less dense? How does this support life?
- What are emergent properties of water?
- How does waters specific heat compare to other solvents specific heat? What properties does it have that allows this? What affect does this have on the climate?
- What two properties of water do plants take advantage of, to move water against gravity, explain?
- a Special abilities water takes on when combined with itself (only works with large amounts of molecules, not just a single molecule)
- b Cohesion and Adhesion.
Cohesion - waters ability to stick to ITSELF (other water molecules)
Adhesion - waters ability to stick to OTHER THINGS that are POLAR
- c Hydrogen bonds keep the molecules spread out, so they don't pack together, making them less dense.
The floating ice insulates the body of water underneath it; if ice sank, then all the bodies of water would freeze solid, making life unlivable.
- d Waters specific heat is much higher that that of other solvents; this is because of hydrogen bonding; this keeps temperatures of places near/on bodies of water consistent
- e Hydrogen bonds are the bonds between two polar molecules - one with a partial positive charge and one with a partial negative charge; water is perfect for this because it has the partial negative of Oxygen and the partial positive of Hydrogen.
5 Multiple Choice Questions
- Heat required to convert 1g of liquid into a gaseous state (high); Evaporative cooling is the warmest molecules of a liquid leave as a gas; allows us to sweat, or release heat so we don't die
- 4 and 4
- Amino (-NH₂) (acts as a base, amino acids); N single bonded to 2 H's
- Hydrogen bonds in water hold each other together stronger than they'd bond to the air, for example. Ex: Jesus Christ lizard can walk on water because of it's surface tension; a dragonfly has non-polar exoskeleton so water beads on it
- Acids raise the concentration of H⁺ ions in an aqueous solution (decreases the pH number)
Bases lower the concentration of H⁺ ions (increases the pH number)
5 True/False Questions
What is a buffer? → Buffers are molecules that resist change in pH; they either release H⁺ to lower the pH or take up H⁺ to raise the pH
Does form impact function? → YES!
Draw functional group structure and give molecular formula for: Methyl.
Example? → Methyl (−CH₃) (sex hormones, DNA methylation (when it gets tagged onto your DNA); C single bonded to 3 H's
−C − H
Ex: 5-methyl cytidine
What are the differences between a hydrophilic and hydrophobic substance? → Hydrophilic - attracted to water; polar or ionic; has charge
Hydrophobic - repels water; nonpolar; no charge
Be able to recreate hydrogen bonding in water. →
(see p. 1 slide 4 in ch. 3)