{"scoreShow":"Check","tryAgain":"Retry","scoreExplanation":"Correct answers give +1 point. Incorrect answers give -1 point. The lowest possible score is 0.","question":{"settings":{"size":{"width":820,"height":1920}},"task":{"elements":[{"x":49.81320049813201,"y":39.8936170212766,"width":22.823100835270484,"height":5.016438319703859,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

The rate constants shown in Table 1 indicate that the reactivity of 2,4,6-TCP is much greater at neutral pH than at low pH; this can also be seen in Fig. 2.<\/p>\n"},"subContentId":"f7895854-e618-411c-9127-3d1b443253d8","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":44.680851063829785,"width":24.099564098035117,"height":7.505541682094893,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

This is partly explained by the much lower reactivity of undissociated 2,4,6-TCP with molecular ozone than in its substantially dissociated state at pH 7 .5, and partly by the effect of hydroxyl radical-reactions at the higher pH. <\/p>\n"},"subContentId":"73ab467c-5d23-4995-8f3e-815e8c14a608","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":36.170212765957444,"width":22.823100835270484,"height":1.7614569996540455,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

The latter effect is predominant at high pH<\/p>\n"},"subContentId":"44621138-a951-4bb1-815a-2007df9f7517","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":38.29787234042553,"width":22.823100835270484,"height":4.3143835251833105,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

a previous study has shown a linear increase in pseudo first-order reaction rates with pH in the range of 7 < pH < 11 (Chu and Wong, 2003).<\/p>\n"},"subContentId":"5f215893-a9f8-4753-8d5f-0ec2db5057ce","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":51.59574468085106,"width":24.099564098035117,"height":6.22907841933026,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

The results shown in Fig. 2 indicate that in the early stages of the reaction there is a large overall 03<\/span>:TCP reaction stoichiometry, thus, at a reaction time of 2 min, the stoichiometry is 89 and 47 mol O3<\/span>\/mol TCP at pH 2 and 7.5, respectively. <\/p>\n"},"subContentId":"2910ff3b-f030-48da-bd30-b9149d672cf2","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":42.5531914893617,"width":22.823100835270484,"height":10.058468207624157,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

An indication of the reaction mechanism during the ozonation of TCP is given by the extent of dechlorination. Recent studies (Han et al., 1998; Chu and Wong, 2003) have suggested one specific mechanism whereby a hydroxyl group replaces one chlorine atom to form 2,6-dichloro-benzo-1,4-quinone (DCQ), as indicated in Fig. 3.<\/p>\n"},"subContentId":"3d2e18a4-6baf-4561-8d88-ffec6d6eaabf","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":57.4468085106383,"width":24.099564098035117,"height":7.505541682094893,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

From this it can be seen that the reaction leads to a reduction in solution pH through the formation of HCL To investigate this, the ozonation of TCP at various initial pH levels was carried out without the use of a pH buffer and the results are summarized in Fig. 4.<\/p>\n"},"subContentId":"76cdd159-09e8-4738-8fcc-dbf05366707f","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":51.59574468085106,"width":22.823100835270484,"height":7.505541682094893,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

Evidence of significant proton generation was observed, and the rate of pH reduction increased with the initial pH of the solution. In the reaction scheme shown in Fig. 3, only one chlorine in the TCP is substituted by a hydroxyl group to produce DCQ, H+ and Cl-.<\/p>\n"},"subContentId":"7aab798f-95eb-47a9-90fa-2fd050fd660a","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":64.36170212765957,"width":24.099564098035117,"height":6.22907841933026,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

However, it is likely that further dechlorination of the remaining two chlorine atoms is possible under favourable conditions, such as at high pH where substantial hydroxyl radical generation occurs.<\/p>\n"},"subContentId":"900d86ae-3381-4d13-9d23-e044379c9b91","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":58.51063829787234,"width":22.823100835270484,"height":7.505541682094893,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

It can be seen from Fig. 4 that for the ozone reaction at the initial pH of 8.17 the change in the solution pH suggested a proton generation equivalent to approximately 1 mM, which is stoichiometrically close to the total chlorine mass of the original TCP (0.88 mM).<\/p>\n"},"subContentId":"6e2928d3-a313-4989-b687-02c00cdbc2e6","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":70.2127659574468,"width":24.099564098035117,"height":8.782004944859525,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

However, it should be noted that DCQ can be further degraded by cleavage of the aromatic ring leading to the formation of aliphatic products. These in turn may react with ozone to form organic acids, such as formic acid and acetic glycolic acids (Abe and Tanaka, 1997), thereby reducing the solution pH. <\/p>\n"},"subContentId":"c2c0755b-8025-4b0e-ab4c-832549493f1a","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":65.42553191489361,"width":22.823100835270484,"height":13.887857995918056,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

Direct measurements of chloride concentration were made during the buffered ozone tests and these are shown in Fig. 5. It can be seen that the degradation of TCP (each molecule having three chlorine atoms) generates significant chloride ions as one of the major products. The number of chloride ions released during the TCP degradation was found to range between 1.5 and 1.9 per degraded molecule of TCP, with the number in this range systematically increasing with the extent of TCP degraded. <\/p>\n"},"subContentId":"cb9ae83e-2d11-4a9f-977f-ff0f8386ddd2","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":78.19148936170212,"width":24.099564098035117,"height":6.22907841933026,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

Since this is an average value for the reaction, it indicates that dechlorination is a major reaction mechanism and suggests that for a proportion of the TCP molecules there may be complete dechlorination. <\/p>\n"},"subContentId":"802c50cd-1d23-4924-b66a-05d216996d88","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":84.04255319148936,"width":24.099564098035117,"height":6.22907841933026,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

Since it is speculated that at pH 7.5 a major part of the TCP reaction is via hydroxyl radical attack, it was thought that the generation of OH radicals may be limited in the presence of the carbonate buffer.<\/p>\n"},"subContentId":"227146b7-9585-4c7e-9872-a51ca3d30210","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":0,"y":77.6595744680851,"width":22.823100835270484,"height":26.014258992182064,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

To enhance the concentration of radicals the tests were repeated in the presence of hydrogen peroxide (H2<\/span>O2<\/span>\/ HO-2<\/span> is a promoter of radical-type chain reactions) and the comparative results can be seen in Fig. 5. The concentration ofhydrogen peroxide (15 mM) used in this case corresponded to a final H2<\/span>O2<\/span>:O3<\/span> mass ratio of 0.8 g\/g. It can be observed from Fig. 5 that there was only a very small enhancement (~5%) of TCP degradation when H2<\/span>O2<\/span> was present during the ozonation. A similar effect was observed with a lower H2O2 concentration (7.5 mM) indicating that H2<\/span>O2<\/span> concentration was not a sensitive factor. In contrast, there was a much greater production of chloride, with the number of chloride ions released during the TCP degradation ranging between 1.7 and 2.7 per degraded molecule of TCP, with the number in this range systematically increasing with the extent of TCP degraded.<\/p>\n"},"subContentId":"363263aa-4058-4804-91ba-8e71bf761595","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false},{"x":49.81320049813201,"y":89.8936170212766,"width":24.099564098035117,"height":11.33493147038879,"dropZones":["0","1"],"type":{"library":"H5P.AdvancedText 1.1","params":{"text":"

This considerably higher productivity of chloride ions, without a proportional increase in TCP degradation, suggests that the 03<\/span>\/H2<\/span>O2<\/span> oxidising conditions are able to readily release chloride from intermediate compounds formed from the TCP degradation. It is assumed that the reaction with intermediate compounds is principally through OH\u00b7 radicals, but direct H2<\/span>O2<\/span> oxidation may also occur. <\/p>\n"},"subContentId":"ce066ab3-a66c-4547-b3f0-f85e59990545","metadata":{"contentType":"Text","license":"U","title":"Untitled Text"}},"backgroundOpacity":100,"multiple":false}],"dropZones":[{"x":1.2453300124533002,"y":2.1274473955390087,"width":24.25280199252802,"height":40.208592777085926,"correctElements":["0","2","4","7","11","9","14"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"

result<\/strong> <\/div>\n"},{"x":49.81320049813201,"y":2.1274473955390087,"width":24.891033623910335,"height":45.31444582814446,"correctElements":["1","3","5","6","8","10","13","12","15"],"showLabel":true,"backgroundOpacity":100,"tipsAndFeedback":{"tip":""},"single":false,"autoAlign":true,"label":"
analysis\/discussion<\/strong><\/div>\n"}]}},"overallFeedback":[{"from":0,"to":100}],"behaviour":{"enableRetry":true,"enableCheckButton":true,"singlePoint":false,"applyPenalties":true,"enableScoreExplanation":true,"dropZoneHighlighting":"dragging","autoAlignSpacing":2,"enableFullScreen":false,"showScorePoints":true,"showTitle":true},"grabbablePrefix":"Grabbable {num} of {total}.","grabbableSuffix":"Placed in dropzone {num}.","dropzonePrefix":"Dropzone {num} of {total}.","noDropzone":"No dropzone.","tipLabel":"Show tip.","tipAvailable":"Tip available","correctAnswer":"Correct answer","wrongAnswer":"Wrong answer","feedbackHeader":"Feedback","scoreBarLabel":"You got :num out of :total points","scoreExplanationButtonLabel":"Show score explanation","a11yCheck":"Check the answers. The responses will be marked as correct, incorrect, or unanswered.","a11yRetry":"Retry the task. Reset all responses and start the task over again.","localize":{"fullscreen":"Fullscreen","exitFullscreen":"Exit fullscreen"}}

M2U1 L2 - H5P Matching Activity

Description

Comcourse