Which of the following qualitative tests is used to identify the presence of a carbon-carbon double bond in an organic compound?
Addition of sodium hydrogen carbonate ($NaHCO_3$) resulting in effervescence.
Addition of bromine water ($Br_2(aq)$) resulting in decolourisation.
Reaction with ethanoic acid and concentrated sulfuric acid, producing a sweet, fruity smell.
Addition of acidified potassium dichromate ($K_2Cr_2O_7$) resulting in a colour change from orange to green.
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Create Free Account Log inThis is a free VCE Units 3 & 4 Chemistry practice question worth 1 mark, testing your understanding of Qualitative tests. It falls under How are organic compounds analysed and used? in Unit 4: How are carbon-based compounds designed for purpose?. Submit your answer above to receive instant AI-powered marking and personalised feedback.
Carbon is the basis not only of the structure of living tissues but is also found in fuels, foods, medicines, polymers and many other materials that we use in everyday life. In this unit students investigate the structures and reactions of carbon-based organic compounds, including considering how green chemistry principles are applied in the production of synthetic organic compounds. They study the metabolism of food and the action of medicines in the body. They explore how laboratory analysis and various instrumentation techniques can be applied to analyse organic compounds in order to identify them and to ensure product purity. Students conduct practical investigations related to the synthesis and analysis of organic compounds, involving reaction pathways, organic synthesis, identification of functional groups, direct redox titrations, solvent extraction and distillations. Throughout the unit students use chemistry terminology including symbols, formulas, chemical nomenclature and equations to represent and explain observations and data from their own investigations and to evaluate the chemistry-based claims of others. A student-designed scientific investigation involving the generation of primary data related to the production of energy and/or chemicals and/or the analysis or synthesis of organic compounds is undertaken in either Unit 3 or Unit 4, or across both Units 3 and 4, and is assessed in Unit 4 Outcome 3. The design, analysis and findings of the investigation are presented in a scientific poster format. School-based assessment The student’s level of achievement in Unit 4 will be determined by School-assessed Coursework, which contributes 30 per cent to the study score. Students complete a set of tasks to address Outcomes 1 and 2, and design and conduct a student investigation for Outcome 3. External assessment The level of achievement for Units 3 and 4 is also assessed by an end-of-year examination contributing 50 per cent to the study score.
In this area of study students focus on laboratory and instrumental analyses of organic compounds, and the function of some organic compounds as medicines. They use distillation to separate mixtures, use volumetric analysis to calculate redox quantities, and explore how instrumental analysis is used to ensure the quality of consumer products. Students explain how some medicines that bind to the active sites of enzymes function by inhibiting the enzymes’ mode of action. Outcome 2 On completion of this unit the student should be able to apply qualitative and quantitative tests to analyse organic compounds and their structural characteristics, deduce structures of organic compounds using instrumental analysis data, explain how some medicines function, and experimentally analyse how some natural medicines can be extracted and purified. Key knowledge
qualitative tests for the presence of carbon–carbon double bonds, hydroxyl and carboxyl functional groups
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