Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? Show the absorption of heat by the breaking of hydrogen bonds The bonds that are broken when water vaporizes are hydrogen bonds between water molecules. Which of the following is a hydrophobic material? We can be sure that a mole of table sugar and a mole of vitamin C are equal in their Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake? What is the hydroxide ion concentration of the lake described in question 5? A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (Note: A liter of cold water weighs about 1 kg.) How many grams of acetic acid (C2H4O2) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.) Cells are surrounded by water, and cells themselves consist of about 70 to 95% water. As a result, _____. (see book section: Concept 3.1: Polar covalent bonds in water molecules result in hydrogen bonding) All of the listed responses are correct. Water is a polar molecule. This means that _____. the opposite ends of the molecule have opposite electrical charges The partial charges on a water molecule occur because of _____. the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule Because oxygen is more electronegative than hydrogen, electrons of the polar bond spend
more time closer to the oxygen atom, resulting in a slight negative charge on the oxygen atom and slight positive charges on the hydrogen atoms. In a group of water molecules, hydrogen bonds form between _____. the oxygen atom in one water molecule and a hydrogen atom in another water molecule Which of the following accurately relates the emergent properties of water to the effects of global warming in the Arctic? The significant increase in Arctic air temperature over the past 50 years is
causing sea ice to form later in the year, to melt earlier, and to cover a smaller area each year. The warming that has occurred in the Arctic has significantly affected the seasonal balance between ice and liquid water to the degree that sea ice communities are in danger. If water were not a polar molecule, how would the effects of global warming differ from what are currently observed or predicted to occur in the future? The effects would be drastically worse because the loss of the polar nature of water would greatly reduce its specific heat and its ability to moderate temperature. A loss of the polar nature of water would equate to a loss in the ability to form hydrogen bonds. Breaking hydrogen bonds absorbs energy, which accounts for water's high specific heat and its ability to influence and moderate climate. What water-related evidence do scientists have that suggests life may exist on other planets? In 2008, the robotic spacecraft Phoenix found ice present just under the material on Mars's surface, and detected sufficient water vapor in the Martian atmosphere for frost to form. The tendency of water molecules to stay close to each other as a result of hydrogen bonding _____. All of the listed responses are correct. What do cohesion, surface tension, and adhesion have in common with reference to water? All are properties related to hydrogen bonding. Most of water's unique features (for example, its versatility as a solvent, ability to moderate temperature, and cohesive behavior) result from the fact that _____. oxygen attracts electrons more than hydrogen does The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are _____. both caused by water's partial charges The phenomenon responsible for maintaining the upward movement of water through a vessel is _____. cohesion Adhesion is best described as _____. the clinging of one substance to another substance You can fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this phenomenon? surface tension Which action would involve the greatest transfer of heat? condensing 5 g of steam to liquid water Imagine that organisms consisted of 70-95% alcohol instead of 70-95% water. Alcohol's specific heat is about half that of water. How would living things be different? Systems for temperature regulation would
have to be much more efficient. The amount of heat required to change the temperature of 1 g of any substance by one °C is defined as _____. the specific heat of that
substance The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as _____. the heat of vaporization of that substance
The reason that coastal climates are more moderate than inland climates is due primarily to water's high _____. specific heat Sweating has a cooling effect because of water's high _____. heat of vaporization Water molecules have _____ than molecules of similar size, such as ammonia and methane, reflecting its capacity to absorb large amounts of heat. a higher boiling point Because molecules of water are farther apart in ice than in liquid water, _____. ice floats Water is a very versatile solvent because water molecules are _____. polar How does the polarity of water contribute to its ability to dissolve so many substances? Because it
is polar, water's oppositely charged ends are attracted to positively and negatively charged ions and molecules. Water molecules form a hydration shell around oppositely charged particles. Polar water molecules surround the individual ions or charged molecules, separating and shielding the ions or molecules from one another. Nonpolar molecules that cluster away from water molecules are called _____ molecules. hydrophobic A molecule that has all nonpolar covalent bonds would be _____. hydrophobic Hydrophobic molecules are _____ water. repelled by Why are cell membranes composed primarily of hydrophobic molecules? In order to perform their function of separating the aqueous solutions outside of cells from the aqueous solutions inside of cells, cell membranes cannot be soluble in water. If cell membranes were hydrophilic, they would break down and dissolve in the presence of water, rendering them useless as a barrier.
Hydrophilic substances, but not hydrophobic substances, _____. have charges and partial charges to which water molecules can adhere Hydrophilic substances are water loving and have an affinity for water. There is an unequal sharing of electrons resulting in a polar molecule, or there is the gain or loss of an electron(s) resulting in the formation of negatively and positively charged ions. Some substances, such as oil and gasoline, will not dissolve in water because _____. their molecules have no charges or partial charges to which water molecules can adhere Sucrose has a molecular mass of 342 daltons. To make a 2-molar (2 M) solution of sucrose, _____. stir 342 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 0.5 L A mole of ethyl alcohol weighs 46 g. How many grams of ethyl alcohol are needed to produce 1 L of a 2-millimolar (2 mM) solution? 0.092 g This would produce a 0.002 M or a 2 mM solution. a compound that donates hydrogen ions to a solution Adding acid tends to _____ of a solution. increase the hydrogen ion concentration and lower the pH Because pH is a negative log, its value is inversely proportional to the hydrogen ion concentration. Which of the following dissociations is that of an acid? HF → H+ + F- Hydrofluoric acid (HF) dissociates into a hydrogen ion and a fluoride ion. A glass of grapefruit juice, at pH 3, contains _____ H+ as a glass of tomato juice, at pH 4. ten times as much A solution at pH 6 contains _____ than the same amount of solution at pH 8. 100 times more H+ Adding a base tends to _____ of a solution. lower the hydrogen ion concentration and increase the pH A substance that reduces the hydrogen ion concentration is a base. Reducing the hydrogen ion concentration increases the pH. When the pH of a solution shifts from 7 to 3, how has the hydrogen ion concentration changed? It has increased by 10,000 times. Pure water has a pH of 7. Why does uncontaminated rainwater have a pH of 5.6? formation of carbonic acid from carbon dioxide and water A substance that minimizes changes in the concentration of H+ and OH- in a solution is a _____. buffer Why is the increasing amount of carbon dioxide being taken up by the oceans a cause for concern? More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to a decrease in the concentration of carbonate ion (CO32-). Which of the following statements is true about acid precipitation? It washes away some minerals that are plant nutrients, and causes some toxic minerals to accumulate. Important plant nutrients such as calcium and magnesium may be washed away from the
soil, and aluminum may build up to dangerous levels. The absorption of human-generated CO2 by the oceans _____. increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for calcifying organisms The absorption of CO 2 by the oceans causes an increase in
the carbonic acid, and hydrogen ion concentration (lower pH). What is most directly responsible for water's versatility as a solvent?Because of its polarity and ability to form hydrogen bonds, water makes an excellent solvent, meaning that it can dissolve many different kinds of molecules.
Which of the following is most directly responsible for waters?Which of the following is most directly responsible for water's unique properties? It forms hydrogen bonds.
What is most responsible for water's unique properties?Unique properties of water
Water molecules are polar, with partial positive charges on the hydrogens, a partial negative charge on the oxygen, and a bent overall structure. This is because oxygen is more electronegative, meaning that it is better than hydrogen at attracting electrons.
Which of the following is responsible for the adhesive properties of water?Hydrogen bonds cause water to be exceptionally attracted to each other. Therefore, water is very cohesive.
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Which of the following is most directly responsible for waters versatility as a solvent
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