Labs (SP = science practices)
Separating a Synthetic Pain Relief Mixture
Big Idea 3, Investigation 9, Primary Learning Objective 3.10
Big Idea 3: Changes in matter involve the rearrangement and/or reorganization of atoms and/or the transfer of electrons. Most over-the-counter drugs consist of mixtures, or physical blends, of active drug ingredient(s) and binders. The main characteristic of a mixture is that it has a variable composition—the components of the mixture may be present or mixed in varying proportions. The substances in a mixture retain their distinctive chemical identities, as well as some of their unique physical properties. The purpose of this investigation is to study the physical properties of ingredients in a synthetic pain relief mixture and determine its percent composition. The lab begins with an introductory activity to test the solubility of each possible component in an organic solvent, ethyl acetate, and in a basic aqueous solution of sodium bicarbonate. The results provide a model for the guided-inquiry design of a flow chart that will map the procedure used to separate components in a mixture and determine percent composition. Optional extension activities include varying the amounts of individual components in the synthetic mixtures and analyzing consumer samples. Students may also measure the melting points of the isolated components, acetylsalicylic acid and acetaminophen, to confirm their identity. This advanced inquiry lab enforces understanding of solubility and chemical reactions as students carry out their own step-by-step experiments and work collaboratively with their peers. |
Learning Objective 3.10: The student is able to evaluate the classification of a process as a physical change, chemical change, or ambiguous change based on both macroscopic observations and the distinction between rearrangement of covalent interactions and noncovalent interactions. [See SP 1.4, 6.1, connects to 5.D.2]
|
Science Practices
1.4 The student can use representations and models to analyze situations or solve problems qualitatively and quantitatively. 6.1 The student can justify claims with evidence. Essential knowledge 5.D.2: At the particulate scale, chemical processes can be distinguished from physical processes because chemical bonds can be distinguished from intermolecular interactions. |
Green Chemistry Analysis of a Mixture
Big Idea 3, Investigation 7, Primary Learning Objectives 3.5 and 3.3
Big Idea 3: Changes in matter involve the rearrangement and/or reorganization of atoms and/or the transfer of electrons. Many stoichiometry experiments use hazardous chemicals, generate toxic byproducts, and waste excess chemicals. In this lab activity, students design and carry out a green chemistry experiment that can quantitatively measure the weight percent of one compound in a mixture of two compounds. The investigation begins with an introductory activity to verify the decomposition reaction of a solid bicarbonate, either potassium or sodium bicarbonate. Students review the principles of green chemistry and evaluate a high school stoichiometry lab procedure in terms of prevention, atom economy, and use and production of nontoxic materials. Once the introductory activity is completed, students design and carry out an experiment to quantitatively measure the weight percent of solid mixtures containing either sodium carbonate and sodium bicarbonate or potassium carbonate and potassium bicarbonate. Students assess their procedures in terms of the green chemistry principles. |
Learning Objective 3.5: The student is able to design a plan in order to collect data on the synthesis or decomposition of a compound to confirm the conservation of matter and the law of definite proportions. [See SP 2.1, 4.2, 6.4] Learning Objective 3.3: The student is able to use stoichiometric calculations to predict the results of performing a reaction in the laboratory and/or to analyze deviations from the expected results. [See SP 2.2, 5.1] |
2.1 The student can justify the selection of a mathematical routine to solve problems.
2.2 The student can apply mathematical routines to quantities that describe natural phenomena. 4.2 The student can design a plan for collecting data to answer a particular scientific question 5.1 The student can analyze data to identify patterns or relationships. 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models. Essential knowledge |
Qualitative Analysis of Cations
Separation and qualitative analysis of cations and anions
Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangements of atoms. These atoms retain their identity in chemical reactions. Big Idea 3: Changes in matter involve the rearrangement and/or reorganization of atoms and/or the transfer of electrons. Qualitative analysis is an analytical procedure in which the question “what is present?” is answered. In a systematic qualitative analysis scheme, each substance present is separated from the other substances. Then a confirmatory test is used to prove that the isolated substance is the expected one. In this experiment you will analyze a solution that can contain any combination of three different cations. First of all, you will prepare a solution that is “known” to contain all of the ions, and you will analyze this solution to learn the techniques for the analysis. Then you will analyze an “unknown” solution to determine which ions are present and which are absent. You may have one, two or all three cations in your solution. This experiment is carried out on a semi-micro scale. Very small quantities of reagents are used. Cleanliness and a great deal of care are necessary to obtain good results. |
Enduring Understandings and Essential Knowledge
|
Science Practices
4.3 The student can collect data to answer a particular scientific question. 5.1 The student can analyze data to identify patterns or relationships. 6.1 The student can justify claims with evidence. Learning Objectives
3.1 The student can translate among macroscopic observations of change, chemical equations, and particle views. 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. |
Acidity of Beverages
Big Idea 1, Investigation 4, Primary Learning Objective 1.20
Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangements of atoms. These atoms retain their identity in chemical reactions. How much acid is in fruit juice? Fruit juices get their sweet taste from sugars and their sour or tart taste from weak acids such as citric acid. If the juice contains too much sugar, it will taste bland, but too much acid and the juice will taste sour. The concentration of acids in various consumer beverages may be determined by titration with sodium hydroxide. This advanced inquiry lab begins with an introductory activity for determining the proper indicator to use in the titration of acetic acid, a characteristic weak acid. The results provide a model for guided-inquiry design of a titration procedure to obtain titration curve data and calculate the molar concentration of acid in a beverage. Experiments may be performed as a cooperative class study or as open-inquiry activities. Three juice samples are provided, but students may also use any other light-colored soft drink or beverage. A wonderful real-world example of everyday chemistry that fulfills key learning objectives such as designing experiments, interpreting data, and using stoichiometric calculations to predict reaction results! |
Primary Learning Objective 1.20
The student can design, and/or interpret data from, an experiment that uses titration to determine the concentration of an analyte in a solution. [See SP4.2, 5.1, 6.4] |
4.2 The student can design a plan for collecting data to answer a particular scientific question
5.1 The student can analyze data to identify patterns or relationships. 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models. |