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According to Table F, which ions combine with chloride ions to form an insoluble compound?*
Which element has the highest boiling point at standard pressure?*
Based on Table F, which compound is least soluble in water?*
Compared to a 1.0-mole sample of NaCl(s), a 1.0-mole sample of NaCl(ℓ) has a different*
At standard pressure, CH4 boils at 112 K and H2O boils at 373 K. What accounts for the higher boiling point of H2O at standard pressure?*
Base your answers to questions 6 on the information below and on your knowledge of chemistry.
The formulas and the boiling points at standard pressure for ethane, methane, methanol, and water are shown in the table below.
Explain, in terms of molecular polarity, why the solubility of methanol in water is greater than the solubility of methane in water.*
Base your answers to questions 7 on the information below and on your knowledge of chemistry.
A solution of ethylene glycol and water can be used as the coolant in an engine-cooling system. The ethylene glycol concentration in a coolant solution is often given as percent by volume. For example, 100. mL of a coolant solution that is 40.% ethylene glycol by volume contains 40. mL of ethylene glycol diluted with enough water to produce a total volume of 100. mL. The graph below shows the freezing point of coolants that have different ethylene glycol concentrations.
Explain, in terms of the molecular polarity, why ethylene glycol dissolves in water to form a solution.*
Base your answers to questions 8 on the information below and on your knowledge of chemistry.
Chemical concepts are applied in candy making. A recipe for making lollipops is shown below.
Explain, in terms of the polarity of sugar molecules, why the sugar dissolves in water.*
Base your answers to questions 9 on the information below and on your knowledge of chemistry.
At standard pressure, water has unusual properties that are due to both its molecular structure and intermolecular forces. For example, although most liquids contract when they freeze, water expands, making ice less dense than liquid water. Water has a much higher boiling point than most other molecular compounds having a similar gram-formula mass.
Explain why H2O(s) floats on H2O(ℓ) when both are at 0ºC.*
Base your answers to questions 10 on the information below and on your knowledge of chemistry.
The unique odors and flavors of many fruits are primarily due to small quantities of a certain class of organic compounds. The equation below represents the production of one of these compounds.
Explain, in terms of molecular polarity, why reactant 2 is soluble in water.*
Base your answers to questions 11 on the information below and on your knowledge of chemistry.
Carbon dioxide is slightly soluble in seawater. As carbon dioxide levels in the atmosphere increase, more CO2 dissolves in seawater, making the seawater more acidic because carbonic acid, H2CO3(aq), is formed.
Seawater also contains aqueous calcium carbonate, CaCO3(aq), which is used by some marine organisms to make their hard exoskeletons. As the acidity of the sea water changes, the solubility of CaCO3 also changes, as shown in the graph below.
State the trend in the solubility of CaCO3 as seawater becomes more acidic.*
Base your answers to questions 12 on the information below and on your knowledge of chemistry.
Hydrazine, N2H4, is a compound that is very soluble in water and has a boiling point of 113°C at standard pressure. Unlike water, hydrazine is very reactive and is sometimes used as a fuel for small rockets. One hydrazine reaction producing gaseous products is represented by the balanced equation below.
N2H4(ℓ) → N2(g) + 2H2(g) + heat
Explain, in terms of intermolecular forces, why the boiling point of hydrazine at standard pressure is higher than the boiling point of water at standard pressure.*
Base your answers to questions 13 on the information below and on your knowledge of chemistry.
There are several isomers of C6H14. The formulas and boiling points for two of these isomers are given in the table below.
Explain, in terms of intermolecular forces, why isomer 2 boils at a lower temperature than isomer 1.*
Base your answers to questions 14 on the information below and on your knowledge of chemistry.
Ethane, C2H6, has a boiling point of −89°C at standard pressure. Ethanol, C2H5OH, has a much higher boiling point than ethane at standard pressure. At STP, ethane is a gas and ethanol is a liquid.
Compare the intermolecular forces of the two substances at STP.*
State, in terms of molecular polarity, why ethanol is soluble in water.*
