Question: True or false? The position of a

> Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pH values. a. pH = 2.75 b. pH = 12.8 c. pH = 4.33 d. pH = 9.61

> Write the conjugate base for each of the following acids. a. HBrO b. HNO2 c. HSO3- d. CH3NH3+

> What mass of solute is present in 225 mL of 0.355 M KBr solution?

> What mass of NaOH pellets is required to prepare 3.5 L of 0.50 M NaOH solution?

> Calculate the pOH value corresponding to each of the pH values listed, and tell whether each solution is acidic or basic. a. pH = 10.75 b. pH = 3.66 c. pH = 1.98 d. pH = 12.47

> Anions containing hydrogen (for example, HCO3- and H2PO42-) show amphoteric behavior when reacting with other acids or bases. Write equations illustrating the amphoterism of these anions.

> Calculate the pH corresponding to each of the pOH values listed, and indicate whether each solution is acidic, basic, or neutral. a. pOH = 4.32 b. pOH = 8.90 c. pOH = 1.81 d. pOH = 13.1

> Write the conjugate base for each of the following acids: a. H2S b. HS2 c. NH3 d. H2SO3

> Write the conjugate acid for each of the following bases. a. ClO- b. Cl- c. ClO3- d. ClO4-

> Standard silver nitrate solutions are used in the analysis of samples containing chloride ion. How many grams of silver nitrate are needed to prepare 250. mL of a 0.100 M AgNO3 solution?

> If 42.5 g of NaOH is dissolved in water and diluted to a final volume of 225 mL, calculate the molarity of the solution.

> An alcoholic iodine solution (“tincture” of iodine) is prepared by dissolving 5.15 g of iodine crystals in enough alcohol to make a volume of 225 mL. Calculate the molarity of iodine in the solution.

> Standard solutions of calcium ion used to test for water hardness are prepared by dissolving pure calcium carbonate, CaCO3, in dilute hydrochloric acid. A 1.745-g sample of CaCO3 is placed in a 250.0-mL volumetric flask and dissolved in HCl. Then the sol

> How many grams of formaldehyde are in 113.1 mL of a 3.0 M aqueous solution of formaldehyde? The formula for formaldehyde is HCHO.

> A laboratory assistant needs to prepare 225 mL of 0.150 M CaCl2 solution. How many grams of calcium chloride will she need?

> For each pair of concentrations, tell which represents the more basic solution. a. [H+] = 2.02 * 10-7 M or [OH-] = 5.05 * 10-5 M b. [H+] = 1.79 * 10-5 M or [OH-] = 4.21 * 10-6 M c. [H+] = 1.25 * 10-12 M or [OH-] = 6.51 * 10-3 M

> Sulfuric acid has a great affinity for water, and for this reason, the most concentrated form of sulfuric acid available is actually a 98.3% solution. The density of concentrated sulfuric acid is 1.84 g/mL. What mass of sulfuric acid is present in 1.00 L

> For each pair of concentrations, tell which represents the more acidic solution. a. [H+] = 1.2 * 10-3 M or [H+] = 4.5 * 10-4 M b. [H+] = 2.6 * 10-6 M or [H+] = 4.3 * 10-8 M c. [H+] = 0.000010 M or [H+] = 0.0000010 M

> For each of the following solutions, the number of moles of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution. a. 0.754 mol KNO3; 225 mL b. 0.0105 mol CaCl2; 10.2 mL c. 3.15 mol NaCl; 5.00

> For each of the following solutions, the number of moles of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution. a. 0.521 mol NaCl; 125 mL b. 0.521 mol NaCl; 250. mL c. 0.521 mol NaCl; 500. m

> To prepare 500. mL of 1.02 M sugar solution, which of the following would you need? a. 500. mL of water and 1.02 mole of sugar b. 1.02 mole of sugar and enough water to make the total volume 500. mL c. 500. g of water and 1.02 mole of sugar d. 0.51 m

> Write the conjugate acid for each of the following bases: a. PO43- b. IO3- c. NO3- d. NH2-

> A solution labeled “0.25 M AlCl3” would contain mole(s) of Al3+ and mole(s) of Cl- in each liter of the solution.

> A solution you used in last week’s lab experiment was labeled “3 M HCl.” Describe in words the composition of this solution.

> A solvent sold for use in the laboratory contains 0.95% of a stabilizing agent that prevents the solvent from reacting with the air. What mass of the stabilizing agent is present in 1.00 kg of the solvent?

> The “Chemistry in Focus” segment Plants Fight Back discusses how tobacco plants under attack by disease produce salicylic acid. Examine the structure of salicylic acid and predict whether it behaves as a monoprotic or a diprotic acid.

> What mass of each solute is present in 285 g of a solution that contains 5.00% by mass NaCl and 7.50% by mass Na2CO3?

> Hydrogen peroxide solutions sold in drugstores as an antiseptic typically contain 3.0% of the active ingredient, H2O2. Hydrogen peroxide decomposes into water and oxygen gas when applied to a wound according to the balanced chemical equation 2H2O2(aq)

> How many grams of KBr are contained in 125 g of a 6.25% (by mass) KBr solution?

> A solution is to be prepared that will be 4.50% by mass calcium chloride. To prepare 175 g of the solution, what mass of calcium chloride will be needed?

> If 67.1 g of CaCl2 is added to 275 g of water, calculate the mass percent of CaCl2 in the solution.

> Write the formula for the hydronium ion. Write an equation for the formation of the hydronium ion when an acid is dissolved in water.

> Consider the iron alloy described in Question 19. Suppose it is desired to prepare 1.00 kg of this alloy. What mass of each component would be necessary? From 19: A sample of an iron alloy contains 92.1 g Fe, 2.59 g C, and 1.59 g Cr. Calculate the perce

> A sample of an iron alloy contains 92.1 g Fe, 2.59 g C, and 1.59 g Cr. Calculate the percent by mass of each component present in the alloy sample.

> In each of the following chemical equations, identify the conjugate acid–base pairs. a. NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq) b. PO43-(aq) + H2O(l) ⇌ HPO42-(aq) + OH-(aq) c. C2H3O2-(aq) + H2O(l) ⇌ HC2H3O2(aq) + OH-(aq)

> Calculate the mass, in grams, of solute present in each of the following solutions. a. 375 g of 1.51% ammonium chloride solution b. 125 g of 2.91% sodium chloride solution c. 1.31 kg of 4.92% potassium nitrate solution d. 478 mg of 12.5% ammonium nit

> A solution that is 9% by mass glucose contains 9 g of glucose in every g of solution.

> How do we define the mass percent composition of a solution? Give an example of a solution, and explain the relative amounts of solute and solvent present in the solution in terms of the mass percent composition.

> Which of the following acids have relatively strong conjugate bases? a. HCN b. H2S c. HBrO4 d. HNO3

> The label “concentrated H2SO4” on a bottle means that there is a relatively amount of H2SO4 present in the solution.

> A solution is a homogeneous mixture and, unlike a compound, has composition.

> If additional solute is added to a(n) solution, it will dissolve.

> What does it mean to say that a solution is saturated with a solute?

> Which of the following do not represent a conjugate acid–base pair? For those pairs that are not conjugate acid–base pairs, write the correct conjugate acid–base pair for each species in the pair. a. H2SO4, SO42- b. H2PO4-, HPO42- c. HClO4, Cl- d. NH

> Which of the following do not represent a conjugate acid–base pair? For those pairs that are not conjugate acid–base pairs, write the correct conjugate acid–base pair for each species in the pair. a. HI, I- b. HClO, HClO c. H3PO4, PO43- d. H2CO3, CO3

> In a solution, the substance present in the largest amount is called the , whereas the other substances present are called the .

> Suppose you dissolved a teaspoon of sugar in a glass of water. Which substance is the solvent? Which substance is the solute?

> Gaseous phosphorus pentachloride decomposes according to the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) The equilibrium system was analyzed at a particular temperature, and the concentrations of the substances present were determined to be [PCl5] = 1.1 * 10-2

> For the reaction N2(g) + 3Cl2(g) ⇌ 2NCl3(g) an analysis of an equilibrium mixture at a particular temperature is performed. It is found that [NCl3] = 1.9 * 10-1 M, [N2] * 1.4 * 10-3 M, and [Cl2] = 4.3 * 10-4 M. Calculate K for the reaction.

> Write the equilibrium expression for each of the following reactions. a. 2O3( g) ⇌ 3O2( g) b. CH4( g) + 2O2( g) ⇌ CO2( g) + 2H2O( g) c. C2H4( g) + Cl2( g) ⇌ C2H4Cl2( g)

> Write the equilibrium expression for each of the following reactions. a. H2( g) + Br2( g) ⇌ 2HBr( g) b. 2H2( g) + S2( g) ⇌ 2H2S( g) c. H2( g) + C2N2( g) ⇌ 2HCN( g)

> How does an increase in temperature result in an increase in the number of successful collisions between reactant molecules? What does an increase in temperature mean on a molecular basis?

> How does the collision model account for the fact that a reaction proceeds faster when the concentrations of the reactants are increased?

> When writing a chemical equation for a reaction that comes to equilibrium, how do we indicate symbolically that the reaction is reversible?

> For the reaction CaCO3(s) ⇌ CaO(s) + CO2(g) the equilibrium constant K has the form K = [CO2]. Using a handbook to find density information about CaCO3(s) and CaO(s), show that the concentrations of the two solids (the number of moles contained in 1 L o

> Many sugars undergo a process called mutarotation, in which the sugar molecules interconvert between two isomeric forms, finally reaching an equilibrium between them. This is true for the simple sugar glucose, C6H12O6, which exists in solution in isomeri

> What is meant by the solubility product for a sparingly soluble salt? Choose a sparingly soluble salt and show how the salt ionizes when dissolved in water, and write the expression for its solubility product.

> When the volume of a vessel containing a gaseous equilibrium system is decreased, the of the gaseous substances present is initially increased.

> Addition of an inert substance (one that does not participate in the reaction) does not change the of an equilibrium.

> What is a homogeneous equilibrium system? Give an example of a homogeneous equilibrium reaction. What is a heterogeneous equilibrium system? Write two chemical equations that represent heterogeneous equilibria.

> According to Le Châtelier’s principle, when a large excess of a gaseous reactant is added to a reaction system at equilibrium, the amounts of products .

> Equilibria involving reactants or products in more than one state are said to be .

> Consider the equilibrium process depicted in Fig. 17.6. When does the equilibrium state occur? From figure 17.6: Liquid kvel is decreasing. Liquid level remains constant. At first there is a net transfer of molecules After a while, the amount of the

> At the point of chemical equilibrium, the rate of the forward reaction the rate of the reverse reaction.

> What does it mean to say that chemical equilibrium is a dynamic process?

> What does it mean to say that all chemical reactions are, to one extent or another, reversible?

> When a chemical system has reached equilibrium, the concentrations of all reactants and products remain with time.

> Equilibrium may be defined as the of two processes, one of which is the opposite of the other.

> A(n) speeds up a reaction without being consumed.

> The minimum energy required for molecules to react with each other is called the energy.

> What does it mean to say that an acid is weak in aqueous solution? What does this reveal about the ability of the acid’s anion to attract protons?

> Why does an increase in temperature favor an increase in the speed of a reaction?

> Before two molecules can react, chemists envision that the molecules must first collide with one another. Is collision among molecules the only consideration for the molecules to react with one another?

> A saturated solution of nickel(II) sulfide contains approximately 3.6 * 10-4 g of dissolved NiS per liter at 20 °C. Calculate the solubility product Ksp for NiS at 20 °C.

> Why are enzymes important? For example, what is the importance of the enzyme carbonic anhydrase in the body?

> Write the balanced chemical equation describing the dissolving of each of the following sparingly soluble salts in water. Write the expression for Ksp for each process. a. NiS(s) b. CuCO3(s) c. BaCrO4(s) d. Ag3PO4(s)

> Write the balanced chemical equation describing the dissolving of each of the following sparingly soluble salts in water. Write the expression for Ksp for each process. a. AgIO3(s) b. Sn(OH)2(s) c. Zn3(PO4)2(s) d. BaF2(s)

> Which of the following will affect the total amount of solute that can dissolve in a given amount of solvent? a. The solution is stirred. b. The solute is ground to fine particles before dissolving. c. The temperature changes.

> What is the special name given to the equilibrium constant for the dissolving of an ionic solute in water?

> For the reaction N2O4(g) ⇌ 2NO2(g) the equilibrium constant K has the value 8.1 * 10-3 at a particular temperature. If the concentration of N2O4(g) is found to be 5.4 * 10-4 M in the equilibrium system, what is the concentration of NO2(g) under these co

> For the reaction 3O2( g) ⇌ 2O3( g) The equilibrium constant, K, has the value 1.12 * 10-54 at a particular temperature. a. What does the very small equilibrium constant indicate about the extent to which oxygen gas, O2( g), is converted to ozo

> An aqueous solution is to be prepared that will be 7.51% by mass ammonium nitrate. What mass of NH4NO3 and what mass of water will be needed to prepare 1.25 kg of the solution?

> 2H2O(g) ⇌ 2H2(g) + O2(g) K = 2.4 * 10-3 at a given temperature. At equilibrium it is found that [H2O( g)] = 1.1 * 10-1 M and [H2( g)] = 1.9 * 10-2 M. What is the concentration of O2( g) under these conditions?

> How does a catalyst work to speed up a chemical reaction?

> The equilibrium constant for the reaction H2(g) + F2(g) ⇌ 2HF(g) has the value 2.1 * 103 at a particular temperature. When the system is analyzed at equilibrium at this temperature, the concentrations of both H2( g) and F2( g) are found to be 0.0021 M.

> For the reaction CO2( g) + H2( g) ⇌ CO( g) + H2O( g) the equilibrium constant, K, has the value 5.21 * 10-3 at a particular temperature. If the system is analyzed at equilibrium at this temperature, it is found that [CO( g)] = 4.73 * 10-3 M, [H2O( g)] =

> For the reaction 2CO(g) + O2(g) ⇌ 2CO2(g) it is found at equilibrium at a certain temperature that the concentrations are [CO( g)] = 2.7 * 10-4 M, [O2( g)] = 1.9 * 10-3 M, and [CO2( g)] = 1.1 * 10-1 M. Calculate K for the reaction at this temperature.

> Consider the reaction SO2( g) + NO2( g) ⇌ SO3( g) + NO( g) Suppose it is found at a particular temperature that the concentrations in the system at equilibrium are as follows: [SO3( g)] = 4.99 * 10-5 M, [NO( g)] = 6.31 * 10-7 M, [SO2( g)] = 2.11 * 10-2

> For the reaction Br2( g) + 5F2( g) ⇌ 2BrF5( g) the system at equilibrium at a particular temperature is analyzed, and the following concentrations are found: [BrF5( g)] = 1.01 * 10-9 M, [Br2( g)] = 2.41 * 10-2 M, and [F2( g)] = 8.15 * 10-2 M. Calculate

> Suppose a reaction has the equilibrium constant K 5 1.7 * 10-8 at a particular temperature. Will there be a large or small amount of unreacted starting material present when this reaction reaches equilibrium? Is this reaction likely to be a good source o

> Plants synthesize the sugar dextrose according to the following reaction by absorbing radiant energy from the sun (photosynthesis). 6CO2(g) + 6H2O(g) ⇌ C6H12O6(s) + 6O2(g) Will an increase in temperature tend to favor or discourage the productio

> Old fashioned “smelling salts” consist of ammonium carbonate, (NH4)2CO3. The reaction for the decomposition of ammonium carbonate (NH4)2CO3(s) ⇌ 2NH3(g) + CO2(g) + H2O(g) is endothermic. What would be the effect on the position of this equilibrium if th

> A strong acid has a weak conjugate base, whereas a weak acid has a relatively strong conjugate base. Explain.

> How do the properties of a nonhomogeneous (heterogeneous) mixture differ from those of a solution? Give two examples of nonhomogeneous mixtures.

> When molecules collide, a certain minimum energy called the is needed for the reaction to occur.

> The reaction C2H2(g) + 2Br2(g) ⇌ C2H2Br4(g) is exothermic in the forward direction. Will an increase in temperature shift the position of the equilibrium toward reactants or products?

> Hydrogen gas, oxygen gas, and water vapor are in equilibrium in a closed container. Hydrogen gas is injected into the container, and the system is allowed to return to equilibrium. Which of the following occurs? Explain your answer. 2H2( g) + O2( g) ⇌ 2

> Hydrogen gas and chlorine gas in the presence of light react explosively to form hydrogen chloride H2( g) + Cl2( g) ⇌ 2HCl( g) The reaction is strongly exothermic. Would an increase in temperature for the system tend to favor or disfavor the production

> Consider the general reaction 2A( g) + B(s) ⇌ C( g) + 3D( g) ∆H = 1115 kJ/mol which has already come to equilibrium. Predict whether the equilibrium will shift to the left, will shift to the right, or will not be affected if the changes indicated belo

> Suppose the reaction system CH4(g) + 2O2(g) ⇌ CO2(g) + 2H2O(l) has already reached equilibrium. Predict the effect of each of the following changes on the position of the equilibrium. Tell whether the equilibrium will shift to the right, will shift to t