Exam 2: The Chemical Context of Life

A beaker contains 100 mL of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the results of this mixing?

One of the buffers that contributes to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood increases, one would expect

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

You have a freshly prepared 1 M solution of glucose in water. You carefully pour out a 100-mL sample of that solution. How many glucose molecules are included in that 100-mL sample?

A strong acid like HCl

One liter of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4?

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)?

If a salamander relied on hydrogen bonds to cling to surfaces, what type of surface would cause the most problems for this animal?

A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?

Figure 2.6 -What is the atomic number of the cation formed in the reaction illustrated in Figure 2.6?

The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride?

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.

How many molecules of glycerol (C3H8O3; molecular mass = 92) would be present in 1 L of a 1 M glycerol solution?

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, this means that

A given solution contains 0.0001(10-4) moles of hydrogen ions (H+) per liter. Which of the following best describes this solution?