Chapter 8 and 9 chem 103
A solution is prepared by adding 25.0 mL of a 1.30 M AlCl3 solution to a flask, then adding enough water to give a final volume of 200.0 mL. What is the concentration of the diluted 1.30 M AlCl3 solution?
0.163 M AlCl3 C1 V1 = C2 V2 C1 = 1.30 M AlCl3 V1 = 25.0 mL AlCl3 C2 = ? V2 = 200.0 mL AlCl3 (1.30 M AlCl3) (V1 = 25.0 mL AlCl3) = C2 (200.0 mL AlCl3) C2 = 0.163 M AlCl3
How many moles of NaOH would be needed to neutralize 800 mL of 0.600 M CH3COOH?
0.480 moles
Consider the reaction shown below. How many moles of HCl would be needed to react with the Al(OH)3 contained in 1.00 liter of a 0.200 M Al(OH)3 solution? Al(OH)3 (aq) + 3 HCl (aq) → 3 H2O (l) + AlCl3 (aq)
0.600 moles HCl 1.00 liter Al(OH)3 (0.200 mole Al(OH)3 / 1 liter solution) (3 moles HCl / 1 mole Al(OH)3) = 0.600 moles HCl Sig Figs!
Consider the reaction shown below. How many moles of Cl2 gas would be needed to react with 6.00 liters of a 0.250 M NaClO2 solution? 2 NaClO2 (aq) + Cl2 (g) → 2 ClO2 (g) + 2 NaCl (aq)
0.750 moles Cl2 6.00 liters NaClO2 (0.250 moles NaClO2 / 1 liter) (1 mole Cl2 / 2 moles NaClO2) = 0.750 mole Cl2 Sig Figs!
Consider the reaction below for the fermentation of glucose, C6H12O6. What volume of a 1.50 molar glucose solution should be used in order to produce 3.00 moles of ethanol, C2H5OH? C6H12O6 (aq) → 2 C2H5OH (aq) + 2 CO2 (g)
1.00 x 10^3 mL glucose 3.00 moles C2H5OH (1 mole glucose / 2 moles C2H5OH) (1 liter / 1.50 moles glucose) = 1.00 liter = 1.00 x 10^3 mL glucose
If acid rain causes pond water to change from pH 6 to pH 4, the hydronium ion concentration becomes
100 times higher. A pH of 6 corresponds to [H3O+] = 10^-6 M. If the pH decreases to 4, then the [H3O+] was increased to 10^-4 M. That's two powers of 10 higher, which is 100 times higher.
Chloroacetic acid (Ka = 1.4 x 10^-3) is a stronger acid than acetic acid (Ka = 1.8 x 10^-5). Approximately how much stronger is it?
100 times stronger. The acid dissociation constant value for chloroacetic acid (~10-3) is two powers of ten greater than that of acetic acid (~10-5). Two powers of ten is 100, so chloroacetic acid is approximately 100 times stronger than acetic acid, though both are still weak acids. The point is: just like there's a wide range of covalent bond polarities (slightly polar to extremely polar), there's a wide range of proton-donating capability in weak acids (slightly weak to extremely weak).
Assuming that the volumes are additive, what volume of water must be added to 35.0 mL of 12.0 M HCl to make a solution which is 3.00 M?
105 mL C1 V1 = C2 V2 C1 = 12.0 M HCl V1 = 35.0 mL HCl C2 = 3.0 M HCl V2 = ? (12.0 M HCl) (35.0 mL HCl) = (3.0 M HCl) V2 V2 = 140. mL solution total - 35.0 mL conc HCl = 105 mL water
Consider the reaction shown below. What volume of a 2.00 M H2SO4 solution would be needed to react with 0.250 moles of CaCO3? CaCO3 (s) + H2SO4 (aq) → H2CO3 (aq) + CaSO4 (aq)
125 mL H2SO4 0.250 moles CaCO3 (1 mole H2SO4 / 1 mole CaCO3) (1000 mL / 2.00 moles H2SO4) = 125 mL H2SO4
If consuming antacids and proton pump inhibitors causes stomach pH to increase from pH 2 to pH 4, the hydronium ion concentration becomes
2 times higher A pH of 2 corresponds to [H3O+] = 10^-2 M. If the pH increases to 4, then the [H3O+] decreased to 10^-4 M. That's two powers of 10 lower, which is 100 times lower.
Consider the reaction below for the fermentation of glucose, C6H12O6. How many moles of carbon dioxide are produced when the glucose in 500.0 mL of a 2.00 M glucose solution decomposes? C6H12O6 (aq) → 2 C2H5OH (aq) + 2 CO2 (g)
2.00 moles CO2 500.0 mL (2.00 moles glucose / 1000 mL) (2 moles CO2 / 1 mole glucose) = 2.00 moles CO2
How many moles of ClO2 gas would be produced from the reaction of 4.00 liters of a 0.500 M NaClO2 solution? 2 NaClO2 (aq) + Cl2 (g) → 2 ClO2 (g) + 2 NaCl (aq)
2.00 moles ClO2 4.00 liters NaClO2 (0.500 moles NaClO2 / 1 liter) (2 moles ClO2 / 2 moles NaClO2) = 2.00 moles ClO2
Consider the reaction shown below. What volume of 4.00 M NaOH would be needed to react with 10.0 moles of chlorine gas? 2 NaOH (aq) + Cl2 (g) → NaCl (aq) + NaClO (aq) + H2O (l)
5.00 liters NaOH 10.0 moles Cl2 (2 moles NaOH / 1 mole Cl2) (1 liter NaOH / 4.00 moles NaOH) = 5.00 liters NaOH solution
Consider the reaction shown below. What volume of 6.00 M HCl would be needed to react with 1.00 mole of Al(OH)3? Al(OH)3 (g) + 3 HCl (aq) → 3 H2O (l) + AlCl3 (aq)
5.00 x 10^2 mL HCl 1 mole Al(OH)3 (3 moles HCl / 1 mole Al(OH)3) (1000 mL / 6.00 moles HCl) = 5.00 x 10^2 mL HCl
What volume of 6.00 M HCl should be diluted to prepare 1.50 x 103 mL of 0.200 M HCl?
50.0 mL HCl C1 V1 = C2 V2 C1 = 6.00 M HCl V1 = ? C2 = 0.200 M HCl V2 = 1.50 x 10^3 mL HCl (6.00 M HCl) V1 = (0.200 M HCl) (1.50 x 10^3 mL HCl) V1 = 50.0 mL
Consider the reaction shown below. What mass of CaSO4 would be produced if 1.00 liters of a 0.500 M H2SO4 solution reacts with excess CaCO3? CaCO3 (s) + H2SO4 (aq) → H2CO3 (aq) + CaSO4 (aq)
68.1 grams CaSO4 1.00 liter H2SO4 (0.500 moles H2SO4 / 1 liter solution) (1 mole CaSO4 / 1 mole H2SO4) (136.14 grams / 1 mole CaSO4) = 68.1 grams CaSO4
Consider the reaction shown below. What mass of chlorine gas would be needed to react with 2.00 liters of a 0.100 M NaOH solution? 2 NaOH (aq) + Cl2 (g) → NaCl (aq) + NaClO (aq) + H2O (l)
7.09 grams Cl2 2.00 liters NaOH (0.100 moles NaOH / 1 liter) (1 mole Cl2 / 2 moles NaOH) (70.9 grams Cl2 / 1 mole Cl2) = 7.09 grams Cl2
How many ml of 0.125 M NaOH would be needed to titrate 20.00 ml of 0.150 M H3PO4?
72 mL of NaOH
What is the Bronsted-Lowry definition of an acid?
A Bronsted-Lowry acid is a compound that can donate a proton, H+ ion? Bronsted-Lowry acids are the same as Arrhenius acids.
What is the Bronsted-Lowry definition of a base?
A Bronsted-Lowry base is a compound that can accept a proton, H+ ion. All Arrhenius bases are Bronsted-Lowry bases, but not vice versa because NH3 is a Bronsted-Lowry base but not an Arrhenius base because NH3 lacks OH-.
What is a Weak acid?
A Weak acid is a compound that can completely dissolve and partly ionize in water to produce H+ ions. A weak acid is a weak electrolyte. Thing back on what it means to be a weak electrolyte; why can such a solution NOT carry very much of a current.
What is a colligative property?
A colligative property is a solution property that depends only on the concentration of solute particles. Colligative properties concern the number of chemical species in solution.
What is a micelle?
A micelle is an aggregate (or supramolecular assembly) of surfactant molecules dispersed in a liquid colloid. Micelles are fairly large as particle aggregates go. They are big enough to have a pronounced Tyndall effect.
What is the difference between a solute and a solvent in a solution?
A solvent is the major component in a solution and the solute is the minor component.
What is a Strong acid?
A strong acid is a compound that can completely dissolve and completely ionize in water to produce H+ ions. A strong acid is a strong Electrolyte. Thing about what it means to be a strong electrolyte.
What is an electrolyte?
A type of solute that when dissolved in a solution will dissociate into ions which conduct electricity.
How are the freezing point and the vapor pressure affected by the addition of a dissolved solute?
Adding a solute will depress the freezing point of the solution and lower the vapor pressure compared to the solvent alone. Adding a solute to a liquid makes it harder for bulk solvent molecules to leave the liquid because of their attraction to the dissolved solute and harder for the solvent molecules to solidify.
How are the boiling point and the vapor pressure affected by the addition of a dissolved solute?
Adding a solute will elevate the boiling point of the solution and lower the vapor pressure compared to the solvent alone. Adding a solute to a liquid makes it harder for bulk solvent molecules to leave the liquid because of their attraction to the dissolved solute.
What is true of an acidic solution?
An acidic solution contains more hydronium ions than hydroxide ions. Every aqueous solution contains both hydronium and hydroxide ions. Only in a neutral solution are these two ions in equal concentration.
What is true of an alkaline solution?
An alkaline solution has more hydroxide ions than hydronium ions. Every aqueous solution contains both hydronium and hydroxide ions. Only in a neutral solution are these two ions in equal concentration.
The weak acid lactic acid has an acid dissociation constant value Ka = 1.8 x 10^-4. A 0.10 M solution of lactic acid should have a pH value = -log(1.8 x 10 ^-4) = 3.85.
False!! The pH of a weak acid solution is not equal to the -log of its K value!
What is true about fog?
Fog is a colloidal suspension where water droplets are the dispersed phase and air is the dispersing medium. Fog is a colloidal suspension and it demonstrates a strong Tyndall effect. That is why driving in the fog is hindered by turning on you high beams. The water particles in the air just scatter back the light and white out every thing.
Acids and bases are defined as substances that donate or accept:
H+ ions
What is phosphoric acid
H3PO4 and it needs a phosphate anion.
Write a balanced chemical equation for the neutralization reaction of nitric acid with potassium hydroxide.
HNO3 + KOH → KNO3 + H2O
What is nitric acid
HNO3 and it needs a polyatomic anion.
An acid is a compound that dissociates in water to produce ______ions, which are ________
Hydronium ions, which are cations. Hydroxide ions are monovalent (-), diatomic anions.
Which equilibrium constant value below indicates a reaction that goes essentially 100% to completion?
K = 1.0 x 10^14 The K value expresses the relative concentration of reactants and products when a reaction system has reached equilibrium: the rates of the forward and reverse reactions are equal, so there's no net change in the concentrations of the reactants and products. K =[products]/[reactants] The larger the K value, the higher the concentration of products at equilibrium.
Equilibrium constants were measured for a series of reaction of the general type: AB + CD ⇔ AD + BC. These equilibrium constant values are shown below. In which reaction is the concentration of products the largest at equilibrium?
K = 3.5 x 108 The K value expresses the relative concentration of reactants and products when a reaction system has reached equilibrium: the rates of the forward and reverse reactions are equal, so there's no net change in the concentrations of the reactants and products. K =[products]/[reactants] The larger the K value, the higher is the concentration of products at equilibrium.
When 1 mole of NH4OH chemically reacts with 1 mole of HC2H3O2, what salt is formed?
NH4C2H3O2, is the salt.
Formula and charge of the hydroxide ion
OH-
What is osmosis.
Osmosis is the movement of water molecules but not small solutes through a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration. Osmosis is a common cell size regulation method that for one think keeps plant stalks vertical as water raises up in the plant cells.
What is the proper order of increasing solute particles sizes...
Pure solvent, solution, colloid and suspension. Assuming that water is the pure solvent molecule, than it would be the smallest particle in question.
How do soaps clean?
Soap cleans because it contains large molecules which form micelles that trap oil and grease on the interior but attract water molecules on the exterior to form a colloidal dispersion. Micelle formation is interesting and may be part of the mechanism that formed early cell membranes. In cells, there is a double micelle membrane and in soaps there is a single.
What is true about a solution?
Solutes in a true solution will not settle out over time: there is no light scattering Tyndall effect and the solution is a homogenous mixture. True solutions have such small particles that the motion of the solvent molecules will keep them suspended.
What would be the pH of a solution if 0.015 moles of NaOH was mixed with 0.010 moles of HCl?
Solution pH = 11.7
According to the Bronsted-Lowry theory, what is the Bronsted-Lowry acid in the following equation, NH3 + H2O <==> OH- + NH4+
The Bronsted-Lowry acid is H2O The Bronsted-Lowry acid is on the reactant side and contains 1 more proton than the conjugate base on the product side.
According to the Bronsted-Lowry theory, what is the Bronsted-Lowry acid in the following equation, HNO2 + H2O <==> H3O+ + NO2-
The Bronsted-Lowry acid is HNO2 The Bronsted-Lowry acid is on the reactant side and contains 1 more proton than the conjugate base on the product side.
According to the Bronsted-Lowry theory, what is the Bronsted-Lowry base in the following equation, HNO2 + H2O <==> H3O+ + NO2-
The Bronsted-Lowry base is H2O The Bronsted-Lowry base is on the reactant side and contains 1 less proton than the conjugate acid on the product side.
According to the Bronsted-Lowry theory, what is the Bronsted-Lowry base in the following equation, NH3 + H2O <==> OH- + NH4+
The Bronsted-Lowry base is NH3 The Bronsted-Lowry base is on the reactant side and contains 1 less proton than the conjugate acid on the product side.
What is the Tyndall effect?
The Tyndall effect is the scatter of light as it pass through a colloidal suspension. Tyndall effect is about light scatter due to the fact that the particles are big enough to scatter light. That is why driving in the fog is hindered by turning on you high beams. The water particles in the air just scatter back the light and white out every thing.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: the equilibrium mixture is transferred to a container with a much greater volume. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would increasing the volume of the equilibrium mixture affect the concentration of Cl2 gas?
The concentration of Cl2 Gas would decrease. The balanced chemical equation shows that the reactants are two moles of gas (2 HCl), but the products are three moles of gas (2 HI and 1 Cl2). (Remember that the other reactant, I2, is a solid.) Thus increasing the volume of the system would favor the forward reaction, as the reactants have more moles of gas. This is because the equilibrium would shift to compensate for the increased volume: three moles of gas can more efficiently occupy the larger container than two moles of gas. Since Cl2 is one of the two product gases, its concentration would increase.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: HI gas is removed from the reaction container. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would removing HI from the reaction container affect the concentration of Cl2 gas?
The concentration of Cl2 gas would increase. HI is a product of the forward reaction. So if HI is removed from the container, the equilibrium would shift to favor the forward reaction. The equilibrium responds to the removal of a reaction participant by trying to replace whatever was removed from the reaction. (Also realize that if HI is being removed from the container, it's not available to collide with Cl2; the reverse reaction couldn't possibly run if only one of the two participants is available.) With the forward reaction favored to replace the removed HI product, the equilibrium shifted to make more products. Since Cl2 gas is one of those products, its concentration would increase.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: the external pressure is increased, so that the volume of the container decreases. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would increasing the volume of the equilibrium mixture affect the concentration of HCl gas?
The concentration of HCl gas would increase. The balanced chemical equation shows that the reactants are two moles of gas (2 HCl), but the products are three moles of gas (2 HI and 1 Cl2). (Remember that the other reactant, I2, is a solid.) Thus increasing the external pressure / decreasing the volume of the system would favor the forward reaction, as the reactants have more moles of gas. This is because the equilibrium would shift to compensate for the reduced volume: two moles of gas will fit more readily in a smaller container that three moles of gas. Since HCl is the reactant gas, its concentration would increase.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: more HCl gas is added to the reaction container. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would adding HCl to the reaction container affect the amount of I2 solid in the reaction mixture?
The concentration of HCl would decrease. HCl is a reactant in the forward reaction. An equilibrium would respond by using/consuming any reactant that is added to the container. So if more HCl is added to the container, the equilibrium would shift to favor the forward reaction. The incoming HCl molecules would collide with the I2 molecules already present in the container, and together they would be converted to product. Since the I2 solid is being consumed by the forward reaction, the amount of I2 in the reaction mixture would decrease.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: the reaction system is heated by placing the reaction container in an hot water bath. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would increasing the temperature affect the concentration of HCl?
The concentration of HCl would decrease. Since the forward reaction is endothermic, adding heat (raising the temperature) would favor the forward reaction, and the equilibrium would shift to favor the formation of HI and Cl2. HCl is one of the two reactants that would be consumed by the forward reaction, and so its concentration would decrease.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: Cl2 gas is removed from the reaction container. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would removing Cl2 from the reaction container affect the concentration of HCl gas?
The concentration of HCl would decrease. Cl2 is a product of the forward reaction. So if Cl2 is removed from the container, the equilibrium would shift to favor the forward reaction. The equilibrium responds to the removal of a reaction participant by trying to replace whatever was removed from the reaction. (Also realize that if Cl2 is being removed from the container, it's not available to collide with HI; the reverse reaction couldn't possibly run if only one of the two participants is available.) With the forward reaction favored, to replace the removed Cl2, the equilibrium has shifted to make more products. HCl gas is the reactant used to make those products, so it is consumed as it reacts with I2; its concentration decreases.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: heat is removed by placing the reaction vessel in an ice bath. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would decreasing the temperature affect the concentration of HI?
The concentration of HI would decrease. Since the forward reaction is endothermic, the reverse reaction must be exothermic. Thus removing heat would favor the reverse reaction, and the equilibrium would shift to favor the formation of HCl and I2. HI would be consumed by that reverse reaction, and so its concentration would decrease.
According to the Bronsted-Lowry theory, what is the conjugate base in the following equation, NH3 + H2O <==> OH- + NH4+
The conjugate base is OH- The conjugate base is on the product side and contains 1 less proton than the Bronsted-Lowry acid on the reactant side.
According to the Bronsted-Lowry theory, what is the conjugate acid in the following equation, HNO2 + H2O <==> H3O+ + NO2-
The conjugated acid is H3O+ Conjugate acid is on the product side and contains 1 more proton than the base on the reactant side.
What is the dispersing medium?
The dispersing medium is the name for the substance in a colloidal dispersion in the largest amount, which is analogous to the solvent in a true solution. Analogous means being like, or comparable to, or similar. The dispersing medium in a colloidal dispersion is comparable to the solvent in a true solution.
What is the hydroxide ion?
The hydroxide ion is OH- Hydroxide ion is a monovalent (-), diatomic anion.
Names and Ka values for four weak acids are listed below. The Acid Dissociation equilibrium constant (Ka) describes the extent to which the acid dissociates in water: HA (aq) + H2O (l) ⇔ H3O+ (aq) + A- (aq) If a 0.10 M solution is made of each acid, which solution would have the highest pH? hydrofluoric acid (HF), Ka = 6.6 x 10^-4 acetic acid (CH3COOH), Ka = 1.8 x 10^-5 hypochlorous acid (HOCl), Ka = 2.9 x 10^-8 carbonic acid (H2CO3), Ka = 4.3 x 10^-7
The weak acid that would have the highest pH is the one with the smallest Ka value: hypochlorous acid, HOCl. The K value tells you the extent (the yield or degree of completion) of a reaction. The smaller the K value, the lower the concentration of products when the reaction has reached equilibrium. Here the reaction is dissociation of an acid molecule into ions, one of which is the hydronium ion, H3O+. The acid with the smallest Ka value is the one that dissociates to the smallest extent, and produces the lowest hydronium ion concentration. The pH (power of Hydrogen) a way to express the concentration of the hydrogen ion, H+ (or hydronium ion, H3O+) that puts the emphasis on the power of ten (the order of magnitude). Since pH = - log [H+] = - log [H3O+], the lower the hydronium ion concentration, the higher the pH value. Note that we're able to make this simple comparison of Ka values because the question specifies that the solutions all have the same acid concentration.
Names and Ka values for four weak acids are listed below. The Acid Dissociation equilibrium constant (Ka) describes the extent to which the acid dissociates in water: HA (aq) + H2O (l) ⇔ H3O+ (aq) + A- (aq) If a 0.10 M solution is made of each acid, which solution would have the lowest pH? hypochlorous acid (HOCl), Ka = 2.9 x 10^-8 carbonic acid (H2CO3), Ka = 4.3 x 10^-7 hydrofluoric acid (HF), Ka = 6.6 x 10^-4 acetic acid (CH3COOH), Ka = 1.8 x 10^-5
The weak acid that would have the lowest pH is the one with the largest Ka value: hydrofluoric acid, HF. The K value tells you the extent (the yield or degree of completion) of a reaction. The larger the K value, the higher the concentration of products when the reaction has reached equilibrium. Here the reaction is dissociation of an acid molecule into ions, one of which is the hydronium ion, H3O+. The acid with the largest Ka value is the one that dissociates to the greatest extent, and produces the highest hydronium ion concentration. The pH (power of Hydrogen) a way to express the concentration of the hydrogen ion, H+ (or hydronium ion, H3O+) that puts the emphasis on the power of ten (the order of magnitude). Since pH = - log [H+] = - log [H3O+], the higher the hydronium ion concentration, the lower the pH value. Note that we're able to make this simple comparison of Ka values because the question specifies that the solutions all have the same acid concentration.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to shift the equilibrium: more HCl gas is added to the reaction container. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would adding HCl to the reaction container affect the concentration of HI gas?
There would be an increase in HCl concentration HCl is a reactant in the forward reaction. So if more HCl is added to the container, the equilibrium would shift to favor the forward reaction. The equilibrium responds by using/consuming any reactant that is added to the container. So the incoming HCl molecules would collide with the I2 molecules already present in the container, and more product would be formed. Since HI gas is one of those products, its concentration would increase.
HCl and I2 are placed in a reaction vessel. The endothermic forward reaction begins, and after a period of time, the system reaches equilibrium. 2 HCl (g) + I2 (s) ⇔ 2 HI (g) + Cl2 (g) A change is made to the system: a catalyst is added to the reaction mixture. Use LeChatelier's Principle to predict the shift in the equilibrium. Specifically: how would adding a catalyst to the reaction container affect the concentration of HI gas?
There would be no change in the concentration of HI gas. A catalyst increases the rate of both the forward and reverse reactions, by providing an alternate pathway for the reaction to occur that requires less energy. The transition state for a catalyzed reaction is different than that of the non-catalzyed reaction, and it has a lower energy level. So the Activation Energies for both the forward and reverse reactions are decreased, and both reactions will run at higher rates. However, when a catalyst is added to a reaction system that is already at equilibrium, there is no change in that equilibrium.
Which solution is most acidic? [OH-] = 1 x 10^-13 M [H3O+] = 1 x 10^-3 M pOH = 12 pH = 4
To compare the acidity of these solutions, the given responses should all be converted to a pH value. pH = 4 [H3O+] = 1 x 10^-3 M, pH = 3 pOH = 12, so pH = 2 [OH-] = 1 x 10^-13 M, so [H3O+] = 1 x 10^-1 M, and pH = 1 (Or since pOH = 13, pH = 1) so it is the most acidic
Which solution is most basic? [OH-] = 1 x 10^-3 M pOH = 4 [H3O+] = 1 x 10-13 M pH = 12
To compare the acidity/basicity of these solutions, the given responses should all be converted to a pH value. pH = 12 [H3O+] = 1 x 10^-13 M, pH = 13 pOH = 4, so pH = 10 [OH-] = 1 x 10^-3 M, so [H3O+] = 1 x 10^-11 M, and pH = 11 (Or since pOH = 3, pH = 11)
A CHM 105 lab experiment requires the use of a 6.00 M HCl solution. The Beaupre stockroom has only 12.0 M HCl. Doubling the volume of a sample of 12.0 M HCl with water will produce a 6.00 M HCl solution.
True C1 V1 = C2 V2 C1 = 12.0 M HCl V1 C2 = ? V2 = 2V1 (12.0 M HCl) V1 = C2 x 2V1 C2 = 12.0 M HCl / 2 = 6.00 M HCl True, the concentration will halved when the volume is doubled.
A 0.0010 M solution of the strong base NaOH would have a pH = 11. True or false??
True! Since HCl is a strong acid, in aqueous solution it is 100% dissociated into ions. A 0.0010 M NaOH solution would have [OH-] = 0.0010 M = 1.0 x 10^-3 M. Then pOH = -log [OH-] = -log (1.0 x 10^-3 M) = 3 If pOH = 3, then pH = 11, since pH + pOH = 14
A lower pH value corresponds to
a higher hydronium ion concentration. Since pH = -log[H3O+] and [H3O+] [OH-] = 1 x 10^-14 = K a, then a low pH means an acidic solution that has a high hydronium ion concentration and a low hydroxide ion concentration.
A higher pH value corresponds to
a higher hydroxide ion concentration. Since pH = -log[H3O+] and [H3O+] [OH-] = 1 x 10^-14 = K a, then a high pH means a basic solution that has a high hydroxide ion concentration and a low hydronium ion concentration.
Names and Ka values for four weak acids are listed below. The Acid Dissociation equilibrium constant (Ka) describes the extent to which the acid dissociates in water: HA (aq) + H2O (l) ⇔ H3O+ (aq) + A- (aq) If a 0.10 M solution is made of each acid, which solution would have the highest concentration of hydronium ions? Question options: acetic acid (CH3COOH), Ka = 1.8 x 10^-5 carbonic acid (H2CO3), Ka = 4.3 x 10^-7 hypochlorous acid (HOCl), Ka = 2.9 x 10^-8 hydrofluoric acid (HF), Ka = 6.6 x 10^-4
hydrofluoric acid (HF), Ka = 6.6 x 10^-4
An Arrhenius base is a compound that dissociates in water to produce ______ions, which are ________
hydroxide ions which are anions Hydronium ions are polyatomic, monovalent (+) cations.
Names and Ka values for four weak acids are listed below. The Acid Dissociation equilibrium constant (Ka) describes the extent to which the acid dissociates in water: HA (aq) + H2O (l) ⇔ H3O+ (aq) + A- (aq) If a 0.10 M solution is made of each acid, which solution would have the highest concentration of un-dissociated acid molecules? Question options: acetic acid (CH3COOH), Ka = 1.8 x 10^-5 carbonic acid (H2CO3), Ka = 4.3 x 10^-7 hypochlorous acid (HOCl), Ka = 2.9 x 10^-8 hydrofluoric acid (HF), Ka = 6.6 x 10^-4
hypochlorous acid (HOCl), Ka = 2.9 x 10^-8 the weak acid that would have the highest concentration of un-dissociated acid molecules is the one with the smallest Ka value: hypochlorous acid, HOCl. The K value tells you the extent (the yield or degree of completion) of a reaction: The larger the K value, the higher the concentration of products when the reaction has reached equilibrium. The smaller the K value, the lower the concentration of products when the reaction has reached equilibrium (and the higher the concentration of reactants) Here the reaction is dissociation of an acid molecule into ions. The acid with the smallest Ka value is the one that dissociates to the smallest extent, which means it would have the highest concentration of un-dissociated acid molecules (the reactant). Note that we're able to make this simple comparison of Ka values because the question specifies that the solutions all have the same acid concentration.
Which compound has a larger n-value?
ionic CaCl2 The n value is the number of ions from the dissociated species.
What is the new pH of a 100 ml aliquot of 0.5 M HCl diluted to 500 ml?
pH = 1.0
A aqueous solution is found to have a hydronium ion concentration [H3O+] = 1 x10^-10 M. The pH is a way to express the hydronium ion concentration [H3O+] (or hydrogen ion concentration [H+]) of an aqueous solution: pH = - log [H+] = - log [H3O+] Determine the pH of the solution with the hydronium ion concentration above, and indicate whether this solution is acidic, basic, or neutral.
pH = 10, basic
A aqueous solution is found to have a hydroxide ion concentration [OH-] = 1 x10^-10 M. Determine the pH of the solution with the hydroxide ion concentration above, and indicate whether this solution is acidic, basic, or neutral.
pH = 4, acidic If [OH-] = 1 x10^-10 M, then [H3O+] = 1 x10^-4 M, because Kw = [OH-] [H3O+] = 1 x10^-14 Then pH = - log [1 x10^-4 M] = 4 A solution with a pH = 4 is acidic.
A aqueous solution is found to have a hydronium ion concentration [H3O+] = 1 x10^-6 M. The pH is a way to express the hydronium ion concentration [H3O+] (or hydrogen ion concentration [H+]) of an aqueous solution: pH = - log [H+] = - log [H3O+] Determine the pH of the solution with the hydronium ion concentration above, and indicate whether this solution is acidic, basic, or neutral.
pH = 6, acidic
A aqueous solution is found to have a hydroxide ion concentration [OH-] = 1 x10-6 M. Determine the pH of the solution with the hydroxide ion concentration above, and indicate whether this solution is acidic, basic, or neutral.
pH = 8, basic If [OH-] = 1 x10^-6 M, then [H3O+] = 1 x10^-8 M, because Kw = [OH-] [H3O+] = 1 x10^-14 Then pH = - log [1 x10^-8 M] = 8 A solution with a pH = 8 is basic.
Calculate the pH of a buffer solution that contains [H3BO3] = 0.40 M and [NaH2BO3] = 0.20 M? Use pKa = 9.14
pH = 8.84
Which statement is correct for pure water?
pure water contains hydronium and hydroxide ions in equal concentrations Due to the self-ionization of water, pure water contains equal concentrations of the hydroxide and hydronium ions: 1.0 x 10^-7 moles/liter of each ion.
The classification of ammonia (NH3) as a 'weak base' refers to:
the ammonia molecule's limited ability to ionize in water Ammonia (NH3) is classified as a weak base because of its limited ability to ionize in water to produce hydroxide ions. Its ability to ionize is described by its Base Ionization equilibrium constant value of Kb = 1.8 x 10^-5.
Which statement is not correct for a reaction system that has reached equilibrium?
the forward and reverse reactions have stopped When a reaction system has reached equilibrium: - both the forward and reverse reactions are still underway; it's just that they are both running at the same rate - the concentrations of the reactants and products are no longer changing (because both the forward and reverse reactions are running at the same rate) - the system is at steady-state: the rates are steady; the concentrations are steady
