Chapter 2 Questions

Discuss how buffers help prevent drastic swings in pH.

Buffers absorb the free hydrogen ions and hydroxide ions that result from chemical reactions. Because they can bond these ions, they prevent increases or decreases in pH. An example of a buffer system is the bicarbonate system in the human body. This system is able to absorb hydrogen and hydroxide ions to prevent changes in pH and keep cells functioning properly.

A molecule that binds up excess hydrogen ions in a solution is called a(n) ________. a. acid b. isotope c. base d. donator

C

What makes ionic bonds different from covalent bonds?

Ionic bonds are created between ions. The electrons are not shared between the atoms, but rather are associated more with one ion than the other. Ionic bonds are strong bonds, but are weaker than covalent bonds, meaning it takes less energy to break an ionic bond compared with a covalent one.

Which of the following statements is false? a. Molecules with the formulas CH3CH2COOH and C3H6O2 could be structural isomers. b. Molecules must have a double bond to be cis-transisomers. c. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon. d. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon.

C

If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have? a. 54 b. 27 c. 100 d. 108

A

Which of the following statements is not true? a. Water is polar. b. Water stabilizes temperature. c. Water is essential for life. d. Water is the most abundant molecule in the Earth's atmosphere

D

Potassium has an atomic number of 19. What is its electron configuration? a. shells 1 and 2 are full, and shell 3 has nine electrons b. shells 1, 2 and 3 are full and shell 4 has three electrons c. shells 1, 2 and 3 are full and shell 4 has one electron d. shells 1, 2 and 3 are full and no other electrons are present

C

What property of carbon makes it essential for organic life?

Carbon is unique and found in all living things because it can form up to four covalent bonds between atoms or molecules. These can be nonpolar or polar covalent bonds, and they allow for the formation of long chains of carbon molecules that combine to form proteins and DNA.

How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12 has six neutrons. Carbon-13 has seven neutrons.

Each carbon molecule can bond with as many as________ other atom(s) or molecule(s). a. one b. two c. six d. four

D