How do bases respond to acids

The two H atoms form weak hydrogen bonds with the oxygen; they attach to the top of the molecule rather like Mickey Mouse ears. This molecular structure gives the water molecule polarity , or a lopsided electrical charge that attracts other atoms. The end of the molecule with the two H atoms is positively charged. The other end, with the oxygen, is negatively charged. Just like in a magnet, where north poles are attracted to south poles opposites attract , the positive end of the water molecule will connect with the negative end of other molecules.

Water is the only natural substance that can exist in all three states of matter —solid, liquid, and gas—at the temperatures normally found on Earth. Many other substances have to be super-heated or -cooled to change states. The solid state of water i. That is because one end of a polar molecule is more positively charged and one end is more negatively charged. The positively charged end of a polar molecule will be attracted to the negatively charged end of a water molecule, and vice versa.

Likewise, positive ions are attracted to the negative end of the water molecule and vice versa. This molecular attraction is what allows so many substances to dissolve easily in water—the molecules are surrounded by water molecules. Oil and other non-polar solutions do not have positively or negatively charged ends, so water molecules will be attracted to each other rather than the oil.

This is why oil does not mix with water. Davy was born in the county of Cornwall, England, on December 17, He was educated there, becoming apprenticed to a surgeon-apothecary when his father died. A few years later he moved to Bristol and became superintendent of a medical institution.

At the age of 22, he wrote Researches, Chemical and Philosophical about his work on the effects of nitrous oxide later known as laughing gas. He experimented with the gas, even inhaling it himself—one of the supposed causes of the sickness he suffered toward the end of his life.

The next work he did was in electrochemistry. His use of electrolysis passing electric current through a substance to break it down into parts led him to propose correctly that elements in a compound are held together by electrical forces. Davy isolated the elements sodium, magnesium, potassium, calcium, boron along with Gay-Lussac , and barium.

He experimented with iodine, proved that diamonds are formed by carbon, and rightly suggested that acids contain hydrogen. Altogether, Davy isolated more elements than any other chemist did up till the 20 th century. Methane gas in coal mines would explode on contact with the flame of the candles that the miners used for light, causing deaths and damage.

Davy was asked to find a solution. He came up with a design for a lamp that surrounded the flame with fine wire gauze. Now let's look at lye, a strong base with the chemical formula NaOH sodium hydroxide. The sodiums don't do anything important, but the hydroxyls make the solution more basic. One last question: Why are strong acids and strong bases so nasty?

It's because they are out of balance. They either have too many positive charges and are looking for negatives to get back into balance, or they have too many negative charges and are looking for positives to get back into balance.

This makes them very reactive with anything they contact. When the positives and negatives are in equal number, they neutralize each other. What is pH? The pH scale is a measure of acidity on a 14 point scale, where 7 is the neutral midpoint. You can buy electronic pH meters or pH indicator paper from any biological or lab supply company, which can be used to give you an accurate measurement of the acidic or basic quality of substances you want to test.

Try this simulation to determine the pH of some common substances. Optional Mini-Experiment : Make your own pH indicator using red cabbage juice. Blend 2 cups of chopped red cabbage leaves and 1 cup water in a food processor or electric blender until pieces are tiny and uniform. Strain off the solids and keep the liquid. If you don't have a blender, you can also chop the cabbage coarsely and boil it in water for about 5 minutes until the liquid is dark purple.

The authors declare no competing financial interest. Acid-Base Equilibria, Part I. Upper secondary students' misconceptions and difficulties. Chemical Educator. Although several aspects of acid-base chem. The misconceptions of a sample of twelfth-grade Greek students on the subject of acid-base equil. Students' misconceptions and difficulties in understanding and applying the relevant concepts were categorized into seven categories: a dissocn.

Royal Society of Chemistry. The effects on students' achievement and misconceptions of new teaching material developed for the unit 'acids and bases' were studied and the students' attitudes towards chem. The new material included worksheets based on the conceptual conflict strategy. The sample consisted of eighty-eight students.

The research was carried out with an exptl. Attitude Scale' were used to collect data before and after the study as pre-tests and post-tests. The results from the post-tests indicated that the students in the exptl. In addn. This shows that the implementation of the new material produced better results both in terms of achievement and attitude. The students' misconceptions in exptl. Effect of developmental level and disembedding ability on students' conceptual understanding and problem-solving ability.

The effect of two psychometric variables: developmental level i. Disembedding ability clearly had a larger effect. Multiple-regression anal. On the other hand, disembedding ability was involved both in situations that required conceptual understanding alone, esp.

Acid-base titrns. Using a series of qual. The findings indicated that students had considerable difficulty with acid-base chem. Further, most students could not relate the concepts to actual solns. Student difficulties stemmed from a lack of understanding of some underlying chem. The conceptual d. Model Confusion in Chemistry Res. Most org. Recent studies have described undergraduate org. To drive changes in pedagogy and curriculum, however, faculty need to be able to quickly assess students' conceptions of acids and acid strength.

We recently reported on the development and assessment of a nine-item, multiple-tier, multiple-choice concept inventory about acid strength, named ACID I. In this manuscript, we demonstrate that despite this low coeff. Thus, the purpose of this paper is to i report two significant alternative conceptions about acid strength that persist in org. Two types of test conditions were employed within second-semester org. Understanding key foundational principles is vital to learning chem.

In the general chem. This study reports the outcomes of an investigation of org. The results indicated that most students maintain declarative knowledge rooted in general chem. This assertion held true for most participants, whether chem. An outcome-based approach to teaching and learning focuses on what the student demonstrably knows and can do after instruction, rather than on what the instructor teaches.

This outcome-focused approach can then guide the alignment of teaching strategies, learning activities, and assessment. In org. Despite the importance of mastering acid-base concepts and skills, the literature describes many related student difficulties. We identified essential learning outcomes LOs in org.

We constructed the learning outcomes using the Structure of Obsd. We explicitly aligned our courses' learning activities and assessments with those intended learning outcomes, both in the initial introduction of acid-base chem. To clearly communicate these LOs to students and other educators, we described them in an educational graphic.

Using a model-eliciting activity MEA focused on Bronsted acids, this study probed org. The salient finding of this work is that the graduate students in this study considered acidity primarily as a function of bond polarization. Furthermore, although they referred to resonance and inductive effects in their explanations, the participants had difficulty characterizing each phenomenon. Overall, the participants' expressed models suggested that they did not have well-developed conceptions of acids in their minds; rather, their models reflected a rationalization of the data provided in MEA.

As a result the participants' mental models a showed little evidence of the anticipated hybridization of theor. American Society for Biochemistry and Molecular Biology. In foundation biochem. The aim of this study was to explore students' conceptions of pH and their ability to solve problems assocd. The responses given by most students are characteristic of an atomistic approach in which they pay no attention to the structure of the problem and conc.

Many students reported difficulty in understanding what the question was asking and were unable to interpret a simple graph showing the pH activity profile of an enzyme. The most startling finding was the lack of basic understanding of logarithms and the inability of all except one student to perform a simple calcn. This deficiency in high school math. This study has highlighted a widespread deficiency in basic math. Implications for the way in which the concepts of pH and buffers are taught are discussed.

Both upper- and lower-level chem. While it might be reasonable to expect general chem. Anecdotal evidence indicates that this is the case; however, little research exists to describe or explain students' difficulties with buffers. The goal of the research presented in this paper is to det. In order to examine students' experiences with buffers and buffer problems, we first interviewed students about how they understand and visualize buffer systems.

We then asked the students to think aloud as they solved buffer problems and to reflect on what they do and do not understand about buffers. Here, we discuss students' ideas about buffers and how they function, the misconceptions students have about buffers and buffer problems, and the types of support students need to understand buffers and solve buffer problems.

Chemistry in Textbooks and as Presented by Teachers Int. Journal of Chemical Education, Dept. A discussion on Lewis concept and the chem. Models and Modeling in Chemical Education. Google Scholar There is no corresponding record for this reference.

Many studies suggest that students have difficulties in learning acid-base concepts. This study presents some conflicts in the textbook descriptions of these concepts and proposes these to be the cause of the students' difficulties. This is esp. A new relationship is suggested in this study based on the ontol.

Finally, it is suggested that all three concepts be taught for the purpose of understanding not only the concepts but also the developmental nature of scientific theories.

Organic Chemistry , John E. McMurry - Cengage Learning , 8 th ed. Manuscript in preparation. Much effort has been expended in developing improved methods for presenting mechanistic thinking and the curved-arrow notation to org. The little research that has been conducted has mainly focused on understanding the meaning that students assoc.

The current research uses OrganicPad, an innovative, tablet person computer-based structure drawing program, to document our efforts to understand how second-year-level org. Our results reveal a dramatic evolution of mechanistic strategies during the academic year, including a large proportion of students who elect not to use the mechanistic convention in their work.

Since the introduction of Morrison and Boyd's textbook in org. In recent years there have even been several papers in this Journal and others detailing research on how students attend to various aspects of this formalism.

However, there are no explicit articulations of a definition or framework in the chem. Although practicing chemists intuitively know what constitutes mechanistic reasoning, this paper presents results of a nationwide study of org. Although a consensus definition did not emerge from this research, there were several common features to them. These features suggest an activity that has a back-of-the-envelope quality meant to generate possible pathways based on established patterns of reactivity.

Consistent with this view, the experts' focus for skills required to develop dexterity in this type of mechanistic reasoning was on applied ones rather than those that are more theor.

Finally, the principal uses of mechanistic reasoning using EPF, according to the respondents, are to explain and predict outcomes of chem. The ability to use the curved-arrow or electron-pushing formalism is one of the most vital skills in the org.

In this formalism, single- or double-headed curved arrows are used to show the flow of electrons from source to sink. Practicing org. A study probes how graduate-level org. The students' solns. Why Ask Why? A review.

There is a strong case to be made that the goal of science is to develop explanatory theories that help us organize our understanding and make predictions about the natural world.

What then, is the goal of science education. What is it that we want students to know and be able to do, and how do we achieve these goals. Here, I argue that one overarching goal is to help students construct causal, mechanistic explanations of phenomena. In chem. Furthermore, while constructing explanations is an important goal in itself, the very act of constructing explanations helps students develop a deeper understanding, and provides the kind of intellectual satisfaction that memorizing facts cannot.

I hope to convince you that our current approaches to assessing student learning are, in fact, all too often counterproductive and almost certainly contribute to students' inability to connect ideas and develop a useful understanding of chem. I will offer some suggestions how we might design more meaningful approaches to curriculum development and assessment of student understanding. After reading this essay, I hope that I will have convinced you that: i if we value something, we must assess it; ii we cannot assume students will construct a coherent framework from the fragments we teach; and iii we must design assessments that provide us with enough evidence to make an argument that the student understands.

Evidence-Centered Assessment Design. The history of general chem. Those reforms that have been implemented are almost entirely concerned with how the course is taught, rather than what is to be learned.

Here we briefly discuss the history of the general chem. In this light we present a rationale for why curriculum reform is necessary, and how it can be accomplished, based on our current understanding of teaching and learning at the college level.

We present a model for curriculum development based on five important questions: i What should students know ii In what order should they learn it iii What do students bring with them to the course iv What materials are best suited for different purposes and v How can student understanding be assessed.

We use our new general chem. A Comparison of Instructional Approaches J. A Comparison of Instructional Approaches. Williams, Leah C. In this study, we present a multiyear, multi-institutional, longitudinal comparison of how students enrolled in traditional general chem. For multiple cohorts of students at two different universities, we found that students who participate in the CLUE curriculum were significantly more likely than those in a traditional curriculum to indicate correctly that intermol.

In a longitudinal study, we followed the students from one cohort through the subsequent year of org. In general, students who are enrolled in the transformed general chem. The finding that a majority of students leave general chem. Cooper, Melanie M. Because Lewis structures provide a direct connection between mol.

Although a great deal of time and effort has been dedicated to development of "foolproof" rules, students still have problems with the skill.

What is more, many students fail to connect the skill with the reasons for learning it. In fact, it appears that conventional instructional practices involved in teaching Lewis structures are in direct conflict with much of what we know about how people learn. In support of this assertion, we present the results of a mixed-methods study designed to investigate how students at all levels draw Lewis structures, and how students perceive the utility of Lewis structures.

We offer suggestions for alternative methods of developing this skill to provide students with an approach to meaningful learning. Previously, we found that: i many students were unable to construct representations of simple mol. Assuming that lack of an understanding of the purpose of such representations inhibited students' meaningful learning, we have worked to address this "representation problem" explicitly in the context of a novel introductory general chem. CLUE includes a learning progression to help students master the relationships between mol.

Two methods were used to assess student learning: OrganicPad, a tablet-PC program that can recognize, record, and grade student free-form naturalistic structure drawings; and the Implicit Information from Lewis Structures Instrument IILSI , a validated survey that asks students to identify the kinds of information they believe can be deduced from Lewis structures. A comparison of two statistically equiv.

CLUE students were also significantly better at decoding the information that these structures contain. We present evidence that the improvements obsd. The ability to use representations of mol. In this study, we investigate student thinking about IMFs i. That is, their representations varied depending on the IMF. Student written descriptions of intermol.

It was only when the student's representation was consulted that we could det. We believe that in situations where spatial information is crucial, free-form drawn representations are more likely to provide meaningful insight into student thinking.

Doctoral Dissertation, Clemson University, Statistical Power Analysis for the Behavioral Sciences ; 2 ed. The use of the curved-arrow notation to depict electron flow during mechanistic processes is one of the most important representational conventions in the org. Our previous research documented a disturbing trend: when asked to predict the products of a series of reactions, many students do not spontaneously engage in mechanism use even when explicitly prompted to do so.

Building upon those results, this study revealed that students who engaged in mechanism use were better equipped to solve org. Cited By. This article is cited by 67 publications. Journal of Chemical Education , 98 10 , Houchlei, Rosalyn R. Bloch, Melanie M. Journal of Chemical Education , 98 9 , Tucker Elizabeth Pearsall.

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Conrad, Joshua P. Darr, Rachel A. Morgan Theall, Dana L. Journal of Chemical Education , 98 4 , Journal of Chemical Education , 97 12 , Haudek, Melanie M. Journal of Chemical Education , 97 11 , Dood, John C. Fields, Jeffrey R. Journal of Chemical Education , 97 10 , Stowe, Brian J.

Esselman, Vanessa R. Ralph, Aubrey J. Ellison, Jeffrey D.