Reactivity3/3/2023 ![]() See whether any part of the mixture is magnetic. Hold the test tube horizontally and run a magnet under the glass.Prepare a mixture of iron oxide and carbon as in step 2 above.Repeat the experiment using a mixture of carbon powder and magnesium oxide.Also look for any colour change in the tube. Look for any glow that persists well after the tube has been taken out of the flame. Heat the tube strongly with a roaring Bunsen flame. Move the tube from side to side to mix the solids. Mix together one small spatula measure of carbon powder and an equal measure of copper(II) oxide in a test tube.Procedure Class practical: heating carbon with metal oxides Perhaps a box of ‘used test tubes’ can be used for this experiment. ![]() It is not possible to completely clean the test tubes from the class practical.Iron(III) oxide, Fe 2O 3(s) – see CLEAPSS Hazcard HC055A.Copper(II) oxide, CuO(s), (HARMFUL, DANGEROUS FOR THE ENVIRONMENT) – see CLEAPSS Hazcard HC026.Magnesium ribbon, Mg(s) – see CLEAPSS Hazcard HC059A.Magnesium oxide, MgO(s) – see CLEAPSS Hazcard HC059b.Carbon dioxide gas, CO 2(g) – see CLEAPSS Hazcard HC020a.Carbon, C(s) – see CLEAPSS Hazcard HC021.Read our standard health and safety guidance.Carbon dioxide cylinder (or CO 2 gas generator – see standard techniques for generating, collecting and testing gases).Hard glass test tubes, 3 (see note 9 below)ĭemonstration: the reaction of magnesium with carbon dioxide.Equipment ApparatusĬlass practical: heating carbon with metal oxides Students can then observe as the teacher burns magnesium in carbon dioxide, producing carbon and magnesium oxide.Īltogether, the class practical and demonstration should take about one hour. They use their results to determine carbon’s position in the reactivity series. In this experiment, students heat carbon with various metal oxides, looking for evidence of a reaction. RSC Yusuf Hamied Inspirational Science Programme.Introductory maths for higher education.The physics of restoration and conservation.In this case, reactivity may be a positive influence. ![]() If the intent of dietary data collection is to monitor and reinforce dietary change efforts, using a food record as a behavior modification tool has been found to be very effective. Such an effect can be included in statistical modeling, but whether or not this eliminates reactivity bias has not been studied. If the instrument includes multiple days of report, analyses of systematic changes with time can inform researchers as to the extent and directionality of reactivity bias. Respondents can be asked to not alter their normal behavior, but the result of this instruction is unknown. Some strategies can be used to reduce reactivity in dietary assessment instruments. Unannounced 24HRs as well as food frequency questionnaires (FFQ) that query a long period of time in the past are not subject to reactivity, although misreporting may occur (see the Food Frequency Questionnaire Profile). Food records and pre-scheduled 24-hour dietary recalls (24HRs) are subject to reactivity because respondents know that their dietary intakes will be measured on a certain day and can change their behavior (see 24-hour Dietary Recall Profile and Food Record Profile). This is conceptually different from misreporting ( Learn More about Misreporting) of actual dietary intakes, which, among other causes, could arise from social desirability bias ( Learn More about Social Desirability). When an individual changes dietary behaviors due to reactivity, the resulting data may be accurate for the reporting period, but they do not reflect usual dietary intake. Reactivity may stem from a desire to simplify the reporting process (e.g., eating single foods rather than combination foods) or to comply with socially desirable norms (i.e., to avoid criticism or to appear to have a healthy diet). Changes in behavior may include eating different types or amounts of foods than those usually consumed. Reactivity occurs when individuals change their behavior due to awareness that their behavior is being or will be measured.
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