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Show that the pH of a solution is -0.301 when its hydronium ion concentration equals 2 moles/L. Is the solution acidic or basic? When the pH of a solution is 1, the concentration of hydronium ions is 10 -1 M = 0.1 M. Assume that the volume of this solution is 500 mL. What is the pH after 500 mL of water is added? You will need... The three chemicals listed below are all very weak acids because they all have a difficult time losing a hydrogen ion, H + . Upon losing this hydrogen ion, the central atom of each of these molecules... Show that an aqueous solution having a pH of 5 has a hydroxide ion concentration of 1 10 -9 M. When the hydronium ion concentration of a solution is 1 10 -10 M, what is the pH of the solution? Is the solution acidic or basic? When the hydronium ion concentration of a solution is 1 10 -4 M,... Show that the hydroxide ion concentration in an aqueous solution is 1 10 -4 M when the hydronium ion concentration is 1 10 -10 M. Recall that 10 a 10 b = 10 (a+b) . You can see the electrolysis of water by immersing the top of a disposable 9-V battery in salt water. The bubbles that form contain hydrogen gas produced as the water decomposes. Why does this... A battery is made by connecting a metal that tends to lose electrons with another metal that tends to gain electrons. Two metals that make for a good battery are copper and zinc, both of which are... Silver tarnishes because it reacts with the small amounts of smelly hydrogen sulfide, H 2 S, we put into the air as we digest our food. In this reaction, the silver loses electrons to the sulfur. You... What happens to the polarity of oxygen atoms as they transform from molecular oxygen, O 2 , into water molecules, H 2 O? What is iron forced to accept during cathodic protection? What are some differences between corrosion and combustion? What metal coats a galvanized nail? Copper metal reacts slowly with the oxygen in air to form reddish copper(I) oxide, Cu 2 O, which is a compound that coats the surface of older pennies, making them look tarnished. When such a penny... Add about an inch of water to a large test tube followed by a couple drops of phenolphthalein pH indicator, which you will likely need to obtain from your classroom. Add a small pinch of washing... Make a concentrated solution of red cabbage extract by boiling a cup of shredded red cabbage in a cup of water for about 5 minutes. Pour this extract into a large transparent container, such as a... The pH of a solution can be approximated with a pH indicator, which is any chemical whose color changes with pH. Many pH indicators are found in plants; the pigment of red cabbage is a good example.... In what year was the efficient electrolysis of aluminum discovered? What is an example of a metal produced primarily by electrolysis? What is electrolysis, and how does it differ from what goes on inside a battery? What else do fuel cells produce besides electricity? What is the prime difference between a battery and a fuel cell? What type of reaction occurs at the cathode? At the anode? What is the purpose of the salt bridge in a voltaic cell? What happens to a reducing agent as it reduces? Write an equation for the half reaction in which a potassium atom, K, is oxidized. What elements have the greatest tendency to behave as reducing agents? Why arent atmospheric levels of carbon dioxide rising as rapidly as might be expected based on the increased output of carbon dioxide resulting from human activities? What does sulfur dioxide have to do with acid rain? What is the product of the reaction between carbon dioxide and water? As the hydronium ion concentration of a solution increases, does the pH of the solution increase or decrease? What does the pH of a solution indicate? What is true about the relative concentrations of hydronium and hydroxide ions in an acidic solution? How about a neutral solution? A basic solution? Water is 88.88% oxygen by mass. Oxygen is exactly what a fire needs to grow brighter and stronger. So why doesnt a fire grow brighter and stronger when water is added to it? A chemical equation for the combustion of propane, C 3 H 8 , follows. Through this reaction is the carbon oxidized or reduced? C 3 H 8 + 5 O 2 3 CO 2 + 4 H 2 O The general chemical equation for photosynthesis follows. Through this reaction are the oxygens of the water molecules, H 2 O, oxidized or reduced? 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 Pennies manufactured after 1982 are made of zinc metal, Zn, within a coat of copper metal, Cu. Zinc is more easily oxidized than copper. Why, then, dont these pennies quickly corrode? Clorox TM is a laundry bleaching agent used to remove stains from white clothes. Suggest why the name begins with Clor- and ends with -ox. Copper atoms have a greater tendency to be reduced than iron atoms. Was this good news or bad news for the Statue of Liberty, whose copper exterior was originally held together by steel rivets? Iron atoms have a greater tendency to oxidize than copper atoms. Is this good news or bad news for a home in which much of the plumbing consists of iron and copper pipes connected together? Explain. A major source of chlorine gas, Cl 2 , is the electrolysis of brine, which yields concentrated salt water, NaCl(aq). What other two products result from this electrolysis reaction? Write the balanced... Why would a miniaturized fuel cell require a liquid rather than a gaseous fuel? What are some key advantages that a fuel-cell power plant has over a coal-fired power plant? How does turning on the radio while you are driving affect the mileage of your gasoline-consuming car? Study question 73 before attempting to balance both the atoms and the charges of the following chemical equation. Fe 3+ + I - Fe 2+ + I 2 Chemical equations need to be balanced not only in terms of the number of atoms, but also in terms of the charge. In other words, just as there should be the same number of atoms before and after the... The type of iron that the human body needs for good health is the Fe 2+ ion. Cereals fortified with iron, however, usually contain small grains of elemental iron, Fe. What must the body do to this... Unsaturated fatty acids, such as C 12 H 22 O 2 , react with hydrogen gas, H 2 , to form saturated fatty acids, such as C 12 H 24 O 2 . Are the unsaturated fatty acids being oxidized or reduced... Hydrogen sulfide, H 2 S, burns in the presence of oxygen, O 2 , to produce water, H 2 O, and sulfur dioxide, SO 2 . Through this reaction, is sulfur oxidized or reduced? 2 H 2 S + 3 O 2 2 H 2 O + 2... Lakes lying in silicon dioxide, SiO 2 , which contain granite basins, tend to become acidified by acid rain more readily than lakes lying in calcium carbonate, CaCO 3 , wich contain limestone basins.... What happens to the pH of soda water as it loses its carbonation? Pour vinegar onto beach sand from the Caribbean, and the result is a lot of froth and bubbles. Pour vinegar onto beach sand from California, however, and nothing happens. Why? Bubbling carbon dioxide into water causes the pH of the water to go down (become more acidic) because of the formation of carbonic acid. Will the pH also drop when carbon dioxide is bubbled into a... Can an acidic solution be made less acidic by adding an acidic solution? The amphoteric reaction between two water molecules is endothermic, which means the reaction requires the input of heat energy in order to proceed: Thewarmer the water, the more heat energy is... Which should be the stronger base: ammonia, NH 3 , or nitrogen trifluoride, NF 3 ? F- N-F H - N-H Ammonia Nitrogen trifluoride How readily an acid donates a hydrogen ion is a function of how well the acid is able to accommodate the resulting negative charge it gains after donating. Which should be the stronger acid: water or... The main component of bleach is sodium hypochlorite, NaOCl, which consists of sodium ions, Na + , and hypochlorite ions, - OCl. What products are formed when this compound reacts with the... Some molecules are able to stabilize a negative charge by passing it from one atom to the next by a flip-flopping of double bonds. This occurs when the negative charge is one atom away from an oxygen... Does the phosphate ion, a common additive to automatic dishwasher detergent, tend to behave as an acid or as a base? Explain? 0 - P-0 Phosphate ion Many of the smelly molecules of cooked fish are alkaline compounds. How might these smelly molecules be conveniently transformed into less smelly salts just prior to eating the fish? Identify the acid or base behavior of each substance in these reactions. a. b. c. d. 2 H,0 + HCI H;O + Cl + , Ho* + An acid and a base react to form a salt, which consists of positive and negative ions. Which forms the positive ions: the acid or the base? Which forms the negative ions? Rank the following molecules from least oxidized to most oxidized: Ethane Ethanol || - Acetaldehyde Acetic acid Review the concept of electronegativity in Section 15.6, and rank these elements from the weakest to strongest reducing agent: (a) chlorine, Cl; (b) sulfur, S; (c) sodium, Na. Review the concept of electronegativity in Section 15.6, and rank these elements from the weakest to strongest oxidizing agent: (a) chlorine, Cl; (b) sulfur, S; (c) sodium, Na. Rank in order of decreasing pH the rain that fell on the Hawaiian island of Kauai on the mornings of (a) January 18, 1778; (b) December 7, 1941; (c) May 8, 2010. Assume there were no active volcanoes... Within a neutral solution of supercritical water (374C, 218 atm), the pH equals about 2. What is the concentration of hydronium ions within this neutral solution? What is the concentration of... How might warmer oceans accelerate global warming? What element is oxidized in the following equation, and what element is reduced? I 2 + 2 Br - 2 I - + Br 2 What element behaves as the oxidizing agent in the following equation, and what element behaves as the reducing agent? Sn 2+ + 2 Ag Sn + 2 Ag + Why does a salt bridge last only so long? Why is the air over an open flame always moist? Upon ingestion, grain alcohol, C 2 H 6 O, is metabolized into acetaldehyde, C 2 H 4 O, which is a toxic substance that causes the headaches and joint pains typical of a hangover. Is the grain alcohol... Your body creates chemical energy from the food you eat, which contains carbohydrates, lipids, and proteins. These are large molecules that first need to be broken down into simpler molecules, such... Do the digestion and subsequent metabolism of foods and drugs tend to make the molecules of the foods and drugs more or less polar? Rank these covalent bonds in order of increasing bond strength: (a) C C, (b) C = C, (c) C - C. Rank the following in order of increasing number of atoms: (a) 52 g of vanadium, V; (b) 52 g of chromium, Cr; (c) 52 g of manganese, Mn. Use the bond energies in Table 17.1 and the accounting format shown in Section 17.5 to determine whether these reactions are exothermic or endothermic: H 2 + Cl 2 2 HCl 2 HCCH + 5 O 2 4 CO 2 + 2 H... Bakers yeast contains a biological catalyst known as catalase, which catalyzes the transformation of hydrogen peroxide, H 2 O 2 , into oxygen, O 2 , and water, H 2 O. Write a balanced equation for... What is the mass of an oxygen atom in atomic mass units? Which of the following two chemical equations is balanced? 2 C 4 H 10 (g) + 13 O 2 (g) 8 CO 2 (g) + 10 H 2 O(l) 4 C 6 H 7 N 5 O 16 (s) + 19 O 2 (g) 24 CO 2 (g) + 20 NO 2 (g) + 14 H 2 O(g) Rank these compounds in order of increasing boiling point: (a) CH 4 , (b) NH 3 , (c) H 2 O. Rank these compounds in order of increasing symmetry: (a) CH 4 , (b) NH 3 , (c) H 2 O. The brightest star in the sky, Sirius, is about 8 light-years from Earth. Show that if you could somehow travel there at jet-plane speed, 2000 km/h, the trip would take about 4.3 million years. (1... The nighttime sky is full of more than just stars and planets. If you are so lucky as to be in a location where the clear night sky is free from city lights, you must try to find the Andromeda... How do humans generate the air pollutant sulfur dioxide? Which elements have the greatest tendency to behave as oxidizing agents? Why is it easier for the body to excrete a polar molecule than to excrete a nonpolar molecule? What chemistry does the body use to get rid of molecules it no longer needs? Scientists have experimented with ways of enhancing the oceans ability to absorb atmospheric carbon dioxide. Adding powdered iron to a small plot of the ocean, they found, has the effect of fostering... Why are atmospheric CO 2 levels routinely up to 15 ppm higher in the spring than in the fall? Why are seasonal fluctuations in atmospheric CO 2 levels much more pronounced in the Northern Hemisphere... Can industries be trusted to self-regulate the amount of pollution they produce? Is it really necessary for the government to enforce these regulations? Shouldnt the conscience of the consumer and... In the centralized model for generating electricity, a relatively small number of power plants produce the massive amounts of electricity that everyone needs. In the decentralized model, electricity... How do two structural isomers differ from each other? How are two structural isomers similar to each other? What physical property of hydrocarbons is used in fractional distillation? What types of hydrocarbons are more abundant in higher-octane gasoline? To how many atoms is a saturated carbon atom bonded? How many multiple bonds must a hydrocarbon have in order to be classified as unsaturated? What kind of ring do aromatic compounds contain?
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