Exam 2: The Chemical Context of Life

A small birthday candle is weighed.It is then lighted and placed beneath a metal can containing 100 mL of water.Careful records are kept as the temperature of the water rises.Data from this experiment are shown on the graph in Figure 2.9.What amount of heat energy is released in the burning of candle wax? (Note that 1 liter of pure water has a mass of 1 kg. ) Figure 2.9

How many molecules of glycerol (C₃H₈O_3;molecular mass = 92)are present in 1 L of a 0.5 M glycerol solution?

If the pH of a solution is increased from pH 5 to pH 7,it means that the

How does the formation of covalent bonds differ from the formation of ionic bonds between two atoms?

What is the hydrogen ion (H⁺)concentration of a solution of pH 8?

An atom has 6 electrons in its outer shell.How many unpaired electrons does it have?

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

The atomic number of sulfur is 16.Sulfur combines with hydrogen by covalent bonding to form a compound,hydrogen sulfide.Based on the number of valence electrons in a sulfur atom,predict the molecular formula of the compound.

What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms?

Which of the following statements correctly defines 1 kilocalorie?

A covalent bond is likely to be polar when

The nucleus of a nitrogen atom contains 8 neutrons and 7 protons.Which of the following is a correct statement concerning nitrogen?

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.

What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen?

Phosphorus-32,a radioactive isotope of phosphorus-31 (atomic number 15),undergoes a form of radioactive decay whereby a neutron turns into a proton,which is retained in the nucleus and emits radiation in the form of an electron.What is the product of such radioactive decay of phosphorus-32?

You have two beakers.One contains a solution of HCl at pH = 1.0.The other contains a solution of NaOH at pH = 13.Into a third beaker,you slowly and cautiously pour 20 mL of the HCl and 20 mL of the NaOH.After complete stirring,the pH of the mixture will be

The atomic number of nitrogen is 7.Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons?

In a single molecule of water,two hydrogen atoms are bonded to a single oxygen atom by

Which of the following statements about buffer solutions is true?

What is the pH of a solution with a hydroxyl ion (OH^-)concentration of 10^-12 M?