T8-3P1 [250 marks] [1 mark] What is the ph of mol dm 3 sodium hydroxide, NaOH(aq)? K = A. 3 B. 4 C. 10 D. 11

Transcription

1 T8-3P1 [250 marks] 1. What is the ph of mol dm 3 sodium hydroxide, NaOH(aq)? K = w A. 3 B. 4 C. 10 D. 11 Soluble acids and bases ionize in water. Sodium hypochlorite ionizes in water. OCl (aq) + H2O(l) OH (aq) + HOCl(aq) 2a. Identify the amphiprotic species. 2b. Identify one conjugate acid-base pair in the reaction. A solution containing g of an unknown monoprotic acid, HA, was titrated with mol dm 3 NaOH(aq) cm 3 was required to reach the equivalence point. 2c. Calculate the amount, in mol, of NaOH(aq) used.

2 2d. Calculate the molar mass of the acid. 2e. Calculate [H + ] in the NaOH solution.

3 Impurities cause phosphine to ignite spontaneously in air to form an oxide of phosphorus and water. 3a. (i) g of air was heated by the energy from the complete combustion of 1.00 mol phosphine. Calculate the temperature rise using section 1 of the data booklet and the data below. [5 marks] Standard enthalpy of combustion of phosphine, Specific heat capacity of air = 1.00Jg 1K 1 = 1.00 kjkg 1K 1 (ii) The oxide formed in the reaction with air contains 43.6 % phosphorus by mass. Determine the empirical formula of the oxide, showing your method. (iii) The molar mass of the oxide is approximately 285gmol 1. Determine the molecular formula of the oxide.

4 (i) State the equation for the reaction of this oxide of phosphorus with water. 3b. (ii) Predict how dissolving an oxide of phosphorus would affect the ph and electrical conductivity of water. [5 marks] ph: Electrical conductivity: (iii) Suggest why oxides of phosphorus are not major contributors to acid deposition. (iv) The levels of sulfur dioxide, a major contributor to acid deposition, can be minimized by either pre-combustion and post-combustion methods. Outline one technique of each method. Pre-combustion: Post-combustion: The concentration of a solution of a weak acid, such as ethanedioic acid, can be determined by titration with a standard solution of sodium hydroxide, NaOH (aq). 4a. Distinguish between a weak acid and a strong acid. Weak acid: Strong acid:

5 Suggest why it is more convenient to express acidity using the ph scale instead of using the concentration of hydrogen ions. 4b. 4c g of an impure sample of hydrated ethanedioic acid, (COOH) 2H O, was dissolved in water to make 1.00 dm of solution cm 3 samples of this solution were titrated against a mol dm -3 solution of sodium hydroxide using a suitable indicator. (COOH) 2 (aq) + 2NaOH (aq) (COONa) 2 (aq) + 2H2O (l) The mean value of the titre was 14.0 cm 3. (i) Calculate the amount, in mol, of NaOH in 14.0 cm 3 of mol dm -3 solution. (ii) Calculate the amount, in mol, of ethanedioic acid in each 25.0 cm 3 sample. (iii) Determine the percentage purity of the hydrated ethanedioic acid sample. [5 marks]

6 4d. The Lewis (electron dot) structure of the ethanedioate ion is shown below. Outline why all the C O bond lengths in the ethanedioate ion are the same length and suggest a value for them. Use section 10 of the data booklet.

7 Phosphine (IUPAC name phosphane) is a hydride of phosphorus, with the formula PH 3. (i) Draw a Lewis (electron dot) structure of phosphine. 5a. (ii) State the hybridization of the phosphorus atom in phosphine. [8 marks] (iii) Deduce, giving your reason, whether phosphine would act as a Lewis acid, a Lewis base, or neither. (iv) Outline whether you expect the bonds in phosphine to be polar or non-polar, giving a brief reason. (v) Phosphine has a much greater molar mass than ammonia. Explain why phosphine has a significantly lower boiling point than ammonia. (vi) Ammonia acts as a weak Brønsted Lowry base when dissolved in water. Outline what is meant by the terms weak and Brønsted Lowry base. Weak: Brønsted Lowry base:

8 5b. Phosphine is usually prepared by heating white phosphorus, one of the allotropes of phosphorus, with concentrated aqueous sodium hydroxide. The equation for the reaction is: [8 marks] (i) The first reagent is written as P 4, not 4P. Describe the difference between P 4 and 4P. (ii) The ion H2PO 2 is amphiprotic. Outline what is meant by amphiprotic, giving the formulas of both species it is converted to when it behaves in this manner. (iii) State the oxidation state of phosphorus in P 4 and H2PO 2. P 4: H2PO 2 : (iv) Oxidation is now defined in terms of change of oxidation number. Explore how earlier definitions of oxidation and reduction may have led to conflicting answers for the conversion of P 4 to H2PO 2 and the way in which the use of oxidation numbers has resolved this.

9 2.478 g of white phosphorus was used to make phosphine according to the equation: 5c. [4 marks] (i) Calculate the amount, in mol, of white phosphorus used. (ii) This phosphorus was reacted with cm 3 of 5.00 mol dm 3 aqueous sodium hydroxide. Deduce, showing your working, which was the limiting reagent. (iii) Determine the excess amount, in mol, of the other reagent. (iv) Determine the volume of phosphine, measured in cm 3 at standard temperature and pressure, that was produced.

10 Impurities cause phosphine to ignite spontaneously in air to form an oxide of phosphorus and water. 5d. (i) g of air was heated by the energy from the complete combustion of 1.00 mol phosphine. Calculate the temperature rise using section 1 of the data booklet and the data below. [9 marks] Standard enthalpy of combustion of phosphine, Specific heat capacity of air = 1.00Jg 1K 1=1.00kJkg 1K 1 (ii) The oxide formed in the reaction with air contains 43.6% phosphorus by mass. Determine the empirical formula of the oxide, showing your method. (iii) The molar mass of the oxide is approximately 285 g mol 1. Determine the molecular formula of the oxide. (iv) State the equation for the reaction of this oxide of phosphorus with water. (v) Suggest why oxides of phosphorus are not major contributors to acid deposition. (vi) The levels of sulfur dioxide, a major contributor to acid deposition, can be minimized by either pre-combustion and post-combustion methods. Outline one technique of each method. Pre-combustion: Post-combustion: cm 3 of a solution of a strong acid with a ph of 3 is added to a volumetric flask and the total volume is made up to 1.00 dm 3 by adding distilled water. The resulting solution is then thoroughly mixed. What is the ph of the diluted solution? A. 1 B. 2 C. 4 D. 5

11 Across period 3, elements increase in atomic number, decrease in atomic radius and increase in electronegativity. Define the term electronegativity. 7a. 7b. Explain why the atomic radius of elements decreases across the period. 7c. State the equations for the reactions of sodium oxide with water and phosphorus(v) oxide with water. 7d. Suggest the ph of the solutions formed in part (c) (i).

12 7e. Describe three tests that can be carried out in the laboratory, and the expected results, to distinguish between 0.10 moldm 3 HCl(aq) and 0.10 moldm 3 CH 3 COOH(aq). [3 marks] 7f. Explain whether BF can act as a Brønsted-Lowry acid, a Lewis acid or both. 3 Describe the bonding and structure of sodium chloride. 7g.

13 7h. State the formula of the compounds formed between the elements below. Sodium and sulfur: Magnesium and phosphorus: 7i. Covalent bonds form when phosphorus reacts with chlorine to form PCl 3. Deduce the Lewis (electron dot) structure, the shape and [4 marks] bond angle in PCl 3 and explain why the molecule is polar. Lewis (electron dot) structure: Name of shape: Bond angle: Explanation of polarity of molecule: 8. A solution of 50 cm 3 hydrochloric acid has a ph of 4. What is the final ph if 450 cm 3 of water is added? A. 3 B. 4 C. 5 D. 6

14 A student used a ph meter to measure the ph of different samples of water at 298 K. Use the data in the table to identify the most acidic water sample. 9a. 9b. Calculate the percentage uncertainty in the measured ph of the rain water sample. 9c. Determine the ratio of [H + ] in bottled water to that in rain water. [H + ] in bottled water [H + ] in rain water 9d. The acidity of non-polluted rain water is caused by dissolved carbon dioxide. State an equation for the reaction of carbon dioxide with water.

15 A group of students investigated the rate of the reaction between aqueous sodium thiosulfate and hydrochloric acid according to the equation below. Na 2 S 2 O 3 (aq) + 2HCl(aq) 2NaCl(aq) + SO 2 (g) + S(s) + H 2 O(l) The two reagents were rapidly mixed together in a beaker and placed over a mark on a piece of paper. The time taken for the precipitate of sulfur to obscure the mark when viewed through the reaction mixture was recorded. Initially they measured out 10.0 cm 3 of moldm 3 hydrochloric acid and then added 40.0 cm 3 of moldm 3 aqueous sodium thiosulfate. The mark on the paper was obscured 47 seconds after the solutions were mixed. 10a. The teacher made up 2.50 dm 3 of the sodium thiosulfate solution using sodium thiosulfate pentahydrate crystals, Na 2 S 2 O 3 5H 2 O. Calculate the required mass of these crystals. [3 marks]

16 The teacher asked the students to measure the effect of halving the concentration of sodium thiosulfate on the rate of reaction. (i) 10b. State the volumes of the liquids that should be mixed. [4 marks] (ii) State why it is important that the students use a similar beaker for both reactions. (iii) Explain, in terms of the collision theory, how decreasing the concentration of sodium thiosulfate would affect the time taken for the mark to be obscured.

17 (i) Sketch and label, indicating an approximate activation energy, the Maxwell Boltzmann energy distribution curves for two 10c. temperatures, T 1 and T 2 (T 2 > T 1 ), at which the rate of reaction would be significantly different. [6 marks] (ii) Explain why increasing the temperature of the reaction mixture would significantly increase the rate of the reaction. The teacher asked the students to devise another technique to measure the rate of this reaction. (i) One group suggested recording how long it takes for the ph of the solution to change by one unit. Calculate the initial ph of 10d. the original reaction mixture. [3 marks] (ii) Deduce the percentage of hydrochloric acid that would have to be used up for the ph to change by one unit.

18 Another group suggested collecting the sulfur dioxide and drawing a graph of the volume of gas against time. (i) Calculate the volume of sulfur dioxide, in cm, that the original reaction mixture would produce if it were collected at 10e Pa and 300 K. [4 marks] (ii) Suggest why it is better to use a gas syringe rather than collecting the gas in a measuring cylinder over water. A student used a ph meter to measure the ph of different samples of water at 298 K. Use the data in the table to identify the most acidic water sample. 11a.

19 11b. Calculate the percentage uncertainty in the measured ph of the rain water sample. Determine the ratio of [H in bottled water to that in rain water. 11c. + ] [H + ] in bottled water [H + ] in rain water 11d. Determine the concentration of hydroxide ions in the sample of river water. The acidity of non-polluted rain water is caused by dissolved carbon dioxide. State an equation for the reaction of carbon dioxide 11e. with water. Oxidation and reduction can be defined in terms of electron transfer or oxidation numbers. Alcohols with the molecular formula C occur as four structural isomers. Three of the isomers can be oxidized with acidified [9 marks] 12a. 4 H 9 OH potassium dichromate solution to form compounds with the molecular formula C 4 H 8 O. (i) Deduce the half-equation for the oxidation of the alcohol C 4 H 9 OH. (ii) Deduce the overall equation for the redox reaction. (iii) Two of the isomers with the molecular formula C 4 H 9 OH can be oxidized further to form compounds with the molecular formula C 4 H 8 O 2. Deduce the structural formulas of these two isomers.

20 (iv) One isomer cannot be oxidized by acidified potassium dichromate solution. Deduce its structural formula, state its name and identify it as a primary, secondary or tertiary alcohol. Name: Alcohol: (v) All isomers of the alcohol C 4 H 9 OH undergo complete combustion. State an equation for the complete combustion of C 4 H 9 OH.

21 A reactivity series can be experimentally determined by adding the metals W, X, Y and Z to solutions of these metal ions. The following reactions were observed: W 2+ (aq) + X(s) W(s) + X 2+ (aq) Y(s) + W 2+ (aq) Y 2+ (aq) + W(s) Z 2+ (aq) + W(s) Z(s) + W 2+ (aq) Y(s) + X 2+ (aq) Y 2+ (aq) + X(s) (i) 12b. Deduce the order of reactivity of these four metals, from the least to the most reactive. [6 marks] (ii) A voltaic cell is made by connecting a half-cell of X in XCl 2 (aq) to a half-cell of Z in ZCl 2 (aq). Deduce the overall equation for the reaction taking place when the cell is operating. (iii) The standard electrode potential for Z 2+ (aq) + 2e Z(s) is V. State which species is oxidized when this half-cell is connected to a standard hydrogen electrode. (iv) Describe the standard hydrogen electrode including a fully labelled diagram.

22 A student carries out the electrolysis of aqueous potassium iodide, KI, using inert electrodes. 12c. (i) State the half-equation for the reaction that occurs at each electrode. [4 marks] Positive electrode (anode): Negative electrode (cathode): (ii) Suggest, giving a reason, what would happen if the electrodes were changed to aluminium. Three electrolytic cells were set up in series (one cell after the other), as shown below. All of the solutions had a concentration of 1.00 moldm 3. (i) Determine the mass of copper produced at one of the electrodes in cell 2 if the tin electrode in cell 1 decreased in mass by 12d g. [6 marks] (ii) Compare the colour and the ph of the solutions in cells 2 and 3 after the current has been flowing for one hour.

23 (iii) Explain your answer given for part (d) (ii). Colour: ph:

24 A group of students investigated the rate of the reaction between aqueous sodium thiosulfate and hydrochloric acid according to the equation below. Na 2 S 2 O 3 (aq) + 2HCl(aq) 2NaCl(aq) + SO 2 (g) + S(s) + H 2 O(l ) The two reagents were rapidly mixed together in a beaker and placed over a mark on a piece of paper. The time taken for the precipitate of sulfur to obscure the mark when viewed through the reaction mixture was recorded. Initially they measured out 10.0 cm 3 of moldm 3 hydrochloric acid and then added 40.0 cm 3 of moldm 3 aqueous sodium thiosulfate. The mark on the paper was obscured 47 seconds after the solutions were mixed. (i) 13a. State the volumes of the liquids that should be mixed. [3 marks] (ii) State why it is important that the students use a similar beaker for both reactions. (iii) If the reaction were first order with respect to the thiosulfate ion, predict the time it would take for the mark on the paper to be obscured when the concentration of sodium thiosulfate solution is halved.

25 One proposed mechanism for this reaction is: S 2 O 2 3 (aq) + H + (aq) HS 2 O 3 (aq) Fast HS 2 O 3 (aq) + H + (aq) SO 2 (g) + S(s) + H 2 O(l) Slow (i) 13b. Deduce the rate expression of this mechanism. [6 marks] (ii) The results of an experiment investigating the effect of the concentration of hydrochloric acid on the rate, while keeping the concentration of thiosulfate at the original value, are given in the table below. On the axes provided, draw an appropriate graph to investigate the order of the reaction with respect to hydrochloric acid. (iii) Identify two ways in which these data do not support the rate expression deduced in part (i).

26 13c. (i) Sketch and label, indicating an approximate activation energy, the Maxwell Boltzmann energy distribution curves for two temperatures, T 1 and T2 (T 2 > T 1 ), at which the rate of reaction would be significantly different. [6 marks] (ii) Explain why increasing the temperature of the reaction mixture would significantly increase the rate of the reaction. The teacher asked the students to devise another technique to measure the rate of this reaction. (i) One group suggested recording how long it takes for the ph of the solution to change by one unit. Calculate the initial ph of 13d. the original reaction mixture. [3 marks] (ii) Deduce the percentage of hydrochloric acid that would have to be used up for the ph to change by one unit.

27 Another group suggested collecting the sulfur dioxide and drawing a graph of the volume of gas against time. 13e. Calculate the volume of sulfur dioxide, in cm 3, that the original reaction mixture would produce if it were collected at Pa[3 marks] and 300 K. Sulfur dioxide, a major cause of acid rain, is quite soluble in water and the equilibrium shown below is established. 13f. SO 2 (aq) + H 2 O(l) HSO 3 (aq) + H + (aq) [3 marks] Given that the K a for this equilibrium is mol dm 3, determine the ph of a 2.00 mol dm 3 solution of sulfur dioxide. 14. A solution of acid HX has a ph = 1 and a solution of acid HY has a ph = 3. Which statement must be correct? A. HX is a stronger acid than HY. B. HY is a stronger acid than HX. C. The [H + ] in the solution of HX is 100 times greater than the [H + ] in the solution of HY. D. The [H + ] in the solution of HY is 100 times greater than the [H + ] in the solution of HX. In acidic solution, ions containing titanium can react according to the half-equation below. TiO 2+ (aq) + 2H + (aq) + e Ti 3+ (aq) + H 2 O(l) State the initial and final oxidation numbers of titanium and hence deduce whether it is oxidized or reduced in this change. 15a.

28 Considering the above equilibrium, predict, giving a reason, how adding more acid would affect the strength of the TiO ion as 15b. 2+ an oxidizing agent. A reactivity series comparing titanium, cadmium and europium is given below. Least reactive Cd < Ti < Eu Most reactive The half-equations corresponding to these metals are: Eu 2+ (aq) + 2e Eu(s) Ti 3+ (aq) + 3e Ti(s) Cd 2+ (aq) + 2e Cd(s) Deduce which of the species would react with titanium metal. 15c. Deduce the balanced equation for this reaction. 15d. 15e. Deduce which of the six species is the strongest oxidizing agent.

29 A voltaic cell can be constructed using cadmium and europium half-cells. State how the two solutions involved should be connected 15f. and outline how this connection works. Some students were provided with a moldm 3 solution of a monobasic acid, HQ, and given the problem of determining whether HQ was a weak acid or a strong acid. Define a Brønsted Lowry acid. 15g. Distinguish between the terms strong acid and weak acid. 15h. Neelu and Charles decided to solve the problem by determining the volume of moldm sodium hydroxide solution needed 15i. 3 to neutralize 25.0 cm 3 of the acid. Outline whether this was a good choice.

30 Neelu and Charles decided to compare the volume of sodium hydroxide solution needed with those required by known 15j moldm 3 strong and weak acids. Unfortunately they chose sulfuric acid as the strong acid. Outline why this was an unsuitable choice. State a suitable choice for both the strong acid and the weak acid. 15k. Strong acid: Weak acid: 15l. Francisco and Shamiso decided to measure the ph of the initial solution, HQ, and they found that its ph was 3.7. Deduce, giving a reason, the strength (weak or strong) of the acid HQ. Suggest a method, other than those mentioned above, that could be used to solve the problem and outline how the results would 15m. distinguish between a strong acid and a weak acid.

31 Acids play a key role in processes in everyday life. The wine industry is important to the economy of many countries. Wine contains ethanol. In a laboratory in Chile, chemists tested the ph of a bottle of wine when opened and found it to have a ph of 3.8. After a few days, the ph had decreased to a. Deduce the change in hydrogen ion concentration, [H + ]. State the name of the compound formed that is responsible for this decreased ph value. 16b. Sulfuric acid present in acid rain can damage buildings made of limestone. Predict the balanced chemical equation for the reaction 16c. between limestone and sulfuric acid including state symbols. Antimony, Sb, forms a fluoride, SbF 5. State the element that you would expect to have chemical properties most similar to those of antimony. 17a.

32 The equilibrium that occurs when antimony(v) fluoride is dissolved in liquid hydrogen fluoride can be represented by the equation below. SbF 5 (s) + 2HF(l) SbF 6 (sol) + H 2 F + (sol) Describe the relationship between SbF and in terms of the Lewis theory of acids. 17b. 5 SbF 6 Explain the behaviour of HF in terms of the Brønsted Lowry theory of acids. 17c. Outline how the following factors account for the fact that HCl is a strong acid and HF is a weak acid. 17d. The strength of the hydrogen halogen bond. The interaction between an undissociated hydrogen halide molecule and a water molecule. 17e.

33 Some students were provided with a moldm 3 solution of a monobasic acid, HQ, and given the problem of determining whether HQ was a weak acid or a strong acid. Neelu and Charles decided to solve the problem by determining the volume of moldm sodium hydroxide solution needed 17f. 3 to neutralize 25.0 cm 3 of the acid. Outline whether this was a good choice. Identify one indicator that could be used when titrating aqueous sodium hydroxide with both a strong acid and a weak acid, and 17g. outline the reason for your choice. Indicator: Reason: Neelu and Charles decided to compare the volume of sodium hydroxide solution needed with those required by known 17h moldm 3 strong and weak acids. Unfortunately they chose sulfuric acid as the strong acid. Outline why this was an unsuitable choice. 17i. Francisco and Shamiso decided to measure the ph of the initial solution, HQ, and they found that its ph was 3.7. Deduce, giving a reason, the strength (weak or strong) of the acid HQ.

34 The second problem set for the students was to determine the acid dissociation constant, K a, of the acid HQ and its pk a. Explain how the pk could be determined from a graph of ph against the volume of sodium hydroxide added. 17j. a moldm 3 Francisco and Shamiso found that the ph of the initial moldm solution was 3.7. However, this reading was inaccurate 17k. 3 because they forgot to wash the ph probe. Calculate the pk a of HQ using the reading they obtained. [4 marks]

35 A student decided to determine the molecular mass of a solid monoprotic acid, HA, by titrating a solution of a known mass of the acid. The following recordings were made. Determine the molecular formula of HA. 18a. To investigate the effect of temperature on the effectiveness of a buffer solution, the student placed 20.0 cm 3 of the buffer solution in a water bath at 24 C. He added small portions of hydrochloric acid, stirring after each addition, until a total of 10 cm 3 was added, and measured the ph continuously during the addition. The procedure was repeated at different temperatures and the results are shown in the following graph. State what is meant by a buffer solution. 18b.

36 With reference to the graph on page 4, describe the effect of increasing temperature on the effectiveness of the buffer solution. 18c. 19. Three aqueous solutions of nitric acid are listed below. W moldm 3 HNO 3 (aq) X. Y moldm 3 HNO 3 (aq) moldm 3 HNO 3 (aq) What is the correct order of increasing ph of these solutions? A. B. C. D. W < X < Y W < Y < X X < W < Y X < Y < W Arsenic and nitrogen play a significant role in environmental chemistry. Arsenous acid, H 3AsO 3, can be found in oxygen-poor (anaerobic) water, and nitrogen-containing fertilizers can contaminate water. (i) 20a. Define oxidation and reduction in terms of electron loss or gain. [9 marks] Oxidation: Reduction: (ii) Deduce the oxidation numbers of arsenic and nitrogen in each of the following species. As 2 O 3 : NO 3 : H 3 AsO 3 : N 2 O 3 : (iii) Distinguish between the terms oxidizing agent and reducing agent. (iv) In the removal of arsenic from contaminated groundwater, H 3 AsO 3 is often first oxidized to arsenic acid, H 3 AsO 4. The following unbalanced redox reaction shows another method of forming H 3 AsO 4. As 2 O 3 (s) + NO 3 (aq) H 3 AsO 4 (aq) + N 2 O 3 (aq) Deduce the balanced redox equation in acid, and then identify both the oxidizing and reducing agents.

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38 Nitric acid, HNO 3, is strong and nitrous acid, HNO 2, is weak. Define an acid according to the Brønsted Lowry and Lewis theories. 20b. Brønsted Lowry theory: Lewis theory: The Lewis (electron dot) structure of nitrous acid is given below. 20c. Identify which nitrogen-oxygen bond is the shorter. Deduce the approximate value of the hydrogen-oxygen-nitrogen bond angle in nitrous acid and explain your answer. 20d.

39 Distinguish between a strong acid and a weak acid in terms of their dissociation in aqueous solution. 20e. Ammonia, NH, is a weak base. Deduce the Lewis (electron dot) structure of NH. State the name of the shape of the molecule 20f. 3 3 and explain why NH3 is a polar molecule. [3 marks] When lime was added to a sample of soil, the ph changed from 5 to 7. Calculate the factor by which the hydrogen ion 20g. concentration changes. One common nitrogen-containing fertilizer is ammonium sulfate. State its chemical formula. 20h. 21. What is the ph of the solution formed when 10 cm 3 of HCl(aq) with ph 1.0 is added to 990 cm 3 of water? A. 1.5 B. 2.0 C. 2.5 D. 3.0

40 Define the term first ionization energy. 22a. 22b. Explain why the first ionization energy of magnesium is higher than that of sodium. Explain why: calcium has a higher melting point than potassium. 22c.

41 sodium oxide has a higher melting point than sulfur trioxide. 22d. [3 marks] Define the terms acid and base according to the Brønsted-Lowry theory and state one example of a weak acid and one example 22e. of a strong base. 22f. Describe two different methods, one chemical and one physical, other than measuring the ph, that could be used to distinguish between ethanoic acid and hydrochloric acid solutions of the same concentration. [4 marks]

42 Black coffee has a ph of 5 and toothpaste has a ph of 8. Identify which is more acidic and deduce how many times the [H is 22g. + ] greater in the more acidic product. Samples of sodium oxide and sulfur trioxide are added to separate beakers of water. Deduce the equation for each reaction and 22h. identify each oxide as acidic, basic or neutral. [3 marks] International Baccalaureate Organization 2017 International Baccalaureate - Baccalauréat International - Bachillerato Internacional Printed for BLUPS