// Numbas version: finer_feedback_settings
{"name": "Chemical Thermodynamics: Path or State Function?", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Chemical Thermodynamics: Path or State Function?", "tags": [], "metadata": {"description": "<p>Public</p>", "licence": "Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International"}, "statement": "", "advice": "<p>A <strong>state function</strong> is defined as a property whose value <strong>does not</strong> depend on the path taken to reach that specific value.</p>\n<p>A <strong>path function</strong> is defined as a property whose value <strong>does</strong> depend on the path taken from the initial to final state of the system it describes.</p>\n<p></p>\n<p></p>\n<p></p>\n<p>(a)&nbsp; &nbsp;The <strong>entropy</strong> of a substance is a <strong>state function</strong> as it is <strong>not</strong> dependent on the history of the substance - for instance, two identical tubs of water both at $\\mathrm{20^\\circ C}$ would have the <strong>same entropy</strong>, but one tub might have been heated up to $\\mathrm{20^\\circ C}$ from $\\mathrm{5^\\circ C}$, whereas the other could have been cooled down to $\\mathrm{20^\\circ C}$ from $\\mathrm{50^\\circ C}$; the history of each tub (the 'path' it took to reach that temperature) is irrelevant, only the current state of the water is important for its entropy value.</p>\n<p></p>\n<p>(b)&nbsp; &nbsp;The <strong>work done</strong> by a body moving between two points is a <strong>path function</strong> as it is dependent on the path taken by the body between these two points, <strong>not</strong> the distance separating the two points. For instance, two cyclists could cycle from one end of a road to another, with one cycling directly along the road between the points, and another travelling off-road into a field, cycling in circles for a few minutes, then cycling back onto the road and to the destination - both cyclists have travelled between the <strong>same two points</strong>, but the off-road cyclist did much <strong>more work</strong> than the one who stayed on the road, so the work done has depended on the <strong>path taken</strong> between the points, <strong>not the distance</strong> separating the points.</p>\n<p></p>\n<p>(c)&nbsp; &nbsp;The <strong>internal energy</strong> of a system is a <strong>state function</strong> as it is <strong>not</strong> dependent on the history of the system; only the <strong>current</strong> properties of the system. This could be considered with the same water bucket example given for entropy - the history of the water would not determine its internal energy.</p>\n<p></p>\n<p>(d)&nbsp; &nbsp;The <strong>enthalpy</strong> of a system is a potential akin to internal energy, and is thus a <strong>state function</strong>.</p>\n<p></p>\n<p>(e)&nbsp; &nbsp;The <strong>time taken to travel home from campus</strong> is a <strong>path function</strong> as it is dependent on the path you take from campus to get back home - on a rainy day, you might decide to take the shortest and most direct route home to get out of the rain as soon as possible, and only take $\\mathrm{25}$ minutes; whereas on a sunny day, you might decide to go for a walk in the park on your way home, and take $\\mathrm{40}$ minutes.</p>\n<p></p>\n<p>(f)&nbsp; &nbsp;<strong>Avogadro's number</strong> is <strong>not a path function</strong>, as it does not depend on any system's history, but is also <strong>not a state function</strong>, as it is not really a property which can depend on anything - it's just a number.</p>", "rulesets": {}, "extensions": [], "builtin_constants": {"e": true, "pi,\u03c0": true, "i": true, "j": false}, "constants": [], "variables": {}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": [], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "gapfill", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "<p>Select whether each of the following is a path function, a state function, or neither:</p>\n<p></p>\n<p>(a)&nbsp; &nbsp;Entropy&nbsp; -&nbsp; [[0]]</p>\n<p></p>\n<p>(b)&nbsp; &nbsp;Work&nbsp; -&nbsp; [[1]]</p>\n<p></p>\n<p>(c)&nbsp; &nbsp;Internal energy&nbsp; -&nbsp; [[2]]</p>\n<p></p>\n<p>(d)&nbsp; &nbsp;Enthalpy&nbsp; -&nbsp; [[3]]</p>\n<p></p>\n<p>(e)&nbsp; &nbsp;The time it takes to travel home from campus&nbsp; -&nbsp; [[4]]</p>\n<p></p>\n<p>(f)&nbsp; &nbsp;Avogadro's number&nbsp; -&nbsp; [[5]]</p>", "gaps": [{"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": [0, "1", 0], "distractors": ["", "", ""]}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": ["1", 0, 0], "distractors": ["", "", ""]}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": [0, "1", 0], "distractors": ["", "", ""]}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": [0, "1", 0], "distractors": ["", "", ""]}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": ["1", 0, 0], "distractors": ["", "", ""]}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minMarks": 0, "maxMarks": 0, "shuffleChoices": false, "displayType": "dropdownlist", "displayColumns": 0, "showCellAnswerState": true, "choices": ["Path function", "State function", "Neither"], "matrix": [0, 0, "1"], "distractors": ["", "", ""]}], "sortAnswers": false}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "contributors": [{"name": "Frances Docherty", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4059/"}, {"name": "Michael McFadden", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/18132/"}]}]}], "contributors": [{"name": "Frances Docherty", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4059/"}, {"name": "Michael McFadden", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/18132/"}]}