Acid-base Solution Research Articles

Pre-service Science Teachers’ Impressions on The Implementation of Small-Scale Chemistry Practicum

This study aims to describe the implementation of the small-scale chemistry approach in the practicum, as well as to show various Pre-service Science Teachers’ impressions. This research is action research involving 69 Pre-service Science Teachers (PSTs), 15 males and 54 females. Collecting data using documentation techniques at each stage of practicum activities, as well as reflection sheets. The results of the documentation are presented and analyzed using narrative descriptions, while the results of the reflections from the PSTs are coded and grouped into (1) the most memorable experiment, (2) positive impressions, and (3) negative impressions. The practicum covers five topics, namely (1) separation of the mixture (filtration), (2) reaction rate, (3) oxidation and reduction reactions (electrolysis), (4) heat transfer (calorimeter), and (5) acid-base solution. The practicum that gave the most impressive was the practicum on acid-base solutions (41.2%), while the one that got the least impressive was the practicum on calorimeters (4.4%). Many positive impressions that appear in practicum activities are “low-cost”, “colorful”, “easy to carry”, “hard to break”, “material savings”, and “more understandable”. The most negative impressions that appear in the series of implementation activities are “limited tools”, “too small-scale tools” and “inaccuracy”. The result of the teacher's reflection finally considers the impression of "limited tools", "material limitation", and "too simple" to be a consideration in developing further practicum activities with the SSC approach.

Flower Extracts of Cage Plants (Canavalia virosa) as an Indicator of Acid Base

Cage plants (Canavalia virosa) are classified as nuts. This study aims to prove the flowers of the cage plants as acid-base indicators and determine the type of acid-base titration that is suitable for indicators of cage plants. The flowers of the cage plants were macerated with ethanol. Extras were tested as indicators in acid-base solutions, buffer solutions, and compared with phenolphthalein and methyl orange for acid-base titration, namely: strong acid with a strong base, a weak acid with a strong base, and weak base with strong acid. The results obtained in this study, namely: flower extracts of cage plants in strong red acid, in weak acid pink, in strong green bases, and weak bases in light green. In a buffer solution of pH 1 to pH 11, the flower extract of the cage plants gives 4 color groups, namely: a buffer solution with pH 1 colored red, pH 3 colored pink, pH 5 to pH 9 being light green, and pH 11 being dark blue. Cage plant flower extract can be used as an indicator of acid-base, cage plant flower extract can be used on strong-base strong acid titration, strong weak-acid base, and weak-strong base acid titration.

Hydrogel sensors with pH sensitivity

The pH-sensitive smart hydrogel sensor was studied. The hydrogel was prepared from polymerization reaction between the 2-hydroxyethyl methacrylate and diallyldimethyammonium chloride using potassium persulfate as an initiator, N, N′-methylenebisacrylamide as a cross-linker and N, N, N′, N′-tetramethylethylenediamine as an accelerator. Bromothymol blue was added to the polymerization system to produce the pH-sensitive hydrogel. The results showed that the hydrogel exhibited properties as a sensor capable of detecting acid–base solutions. The fluid sensing of the hydrogel showed sign of a change in color of the bromothymol blue in the gel. Factor affecting the properties of the hydrogel sensors such as the color change, recovery from bending, and swelling property was the concentration of the diallyldimethyammonium chloride.

Module Development with Problem Based Learning (PBL) Model Based on Environmental Wetland to Increase Students’ Learning Outcomes

<p>Research has been carried out on the development of modules with the Problem Based Learning (PBL) model based on wetland environments on the topic of acid-base solutions. This study aims to determine: the validity, practicality and effectiveness of module development. This study used a research & development design of a 4-D development model that was modified into 3-D, the data collection techniques used a test of student learning outcomes and a questionnaire. The research was conducted at SMAN 3 Banjarmasin with a sample of 10 students of class of XI PMIA 3 for small-scale trials, 24 students of XI PMIA 3 for limited-scale trials, and class of XI PMIA 1 and XI PMIA 2 with total 74 students for testing in a wide scale. Validity can be seen based on the results of the validation, the practicality of the students’ responses, and the effectiveness of the students' learning outcomes. The results showed that the module was considered valid with an average score of 146.4 and a percentage of 91.58% (very valid), practical with a percentage of 82.90% (good), effective with an average N-gain score of 0.84 (high), the average score of N-gain is 0.87 (high) for class of XI PMIA 1 and 0.86 (high) for class of XI PMIA 2. The results of this study indicate that the module with the Problem Based Learning (PBL) model based on the wetland environment on the topic of acid-base solutions is declared valid, practical and effective for use as a learning resource for students.</p><p> <strong><em></em></strong></p>

Fabrication of Superhydrophobic Wood Surface by Etching Polydopamine Coating with Sodium Hydroxide

Superhydrophobic treatment of wood surfaces can effectively prevent the contact between the external moisture and wood, which improves the service life of the wood. In this study, different rough surfaces of wood were constructed, derived from the self-polymerization of dopamine (DA) in weak base solution to form a polydopamine (PDA) coating and the deprotonation of the PDA coating in a strong base solution. Furthermore, octadecyltrichlorosilane (OTS) was used as a low-surface-free-energy agent to modify rough surface in order to prepare superhydrophobic woods: Wood@PDA–NaOH–OTS and the Wood@PDA–NaOH/SiO2–OTS. The contact angles (CAs) and sliding angles (SAs) of the resulting superhydrophobic woods were tested. The results showed that the CA and SA of the Wood@PDA–NaOH–OTS were 151° and 4.8°, respectively; the CA and SA of the Wood@PDA–NaOH/SiO2–OTS were 155.1° and 5.0°, respectively. Surface electron microscopy (SEM) images presented that NaOH successfully etched the PDA coating, and the roughness was further improved by adding nano-SiO2. Atomic force microscope images (AFM) revealed that the nano-SiO2 particles could effectively provide nanolevel roughness, which was beneficial to the wood’s superhydrophobic properties. In addition, the obtained superhydrophobic wood possessed strong surface stability and anti-loss property, as well as resistance to acid-base solution and organic solvent.

Utilization of Kalpataru Flower Extract (Hura crepitans Linn) as an Alternative Acid Base Indicator

Kalpataru flower (Hura crepitans Linn) is an anthocyanin-containing plant. This study aims to utilize extract from the kalpataru flower as an alternative acid base indicator and determine the type of acid-base titration suitable for extracting the kalpataru flower indicator. Kalpataru flowers are macerated with methanol solvent for around 2 hours. Kalpataru flower extract was tested as an indicator in acid-base solution, buffer, and compared with phenolphthalein and methyl orange for acid-base titration, namely: strong acids with strong bases, weak acids with strong bases, and weak bases with strong acids. The results obtained in this study were: indicator extract of brownish yellow kalpataru flowers, in strong red acids, in strong bases of dark green, in weak pink acids, and in weak bases in light green. In the buffer, the indicator extract of the kalpataru flower has a range of pH pH 4-5 (pink-colorless) and pH 9-11 (yellowish green-dark green). The indicator of kalpataru flower extract can be used on strong acid titration with strong bases, weak acids with strong bases and weak bases with strong acids. Kalpataru flower extract can be used as an acid-base indicator.

Effectiveness of Problem Solving Learning Model towards Student Learning Outcomes on Acid-Base Solution in SMA Negeri 1 Buko on Academic Year 2018-2019

This study aimed to determine the effectiveness of problem-solving learning models on students’ learning outcomes in the acid-base solutions topic in SMA Negeri 1 Buko on Academic Year 2018-2019. This type of research was a true experiment with a non-randomized posttest two group design. The population of this research was all students of class XI MIA, the sampling techniques was saturated sampling methods. The sample used was students of class XI MIA 1 and XI MIA 2 as experimental class 1 and experimental class 2. The testing of students’ learning outcomes data was using one-party statistical analysis t-test to test the completeness of individual learning outcomes and classical completeness test to test the overall percentage of mastery learning. The results of data analysis obtained, the mean experimental class 1 (X1) was 75.5 with a standard deviation of 10.71 and the average experimental class 2 (X2) was 76.43 with a standard deviation of 12.77. The results of hypothesis testing with one-party t-test statistics in the experimental class 1 and 2 was obtained tcount > ttable (2.321 > 1.740; 2.306 > 2.101) with a significance level of α = 0.05 and degrees of freedom 18 and 19, then H0 was rejected and Ha was accepted. Then, the result of the classical completeness test obtained in the experimental class 1 were 80% and experimental class 2 were 80.95%. Based on the results of data analysis it can be concluded that the problem-solving learning model is effective against students’ learning outcomes in the acid-base solutions topic in SMA Negeri 1 Buko on Academic Year 2018-2019.

An eco-friendly smart self-healing coating with NIR and pH dual-responsive superhydrophobic properties based on biomimetic stimuli-responsive mesoporous polydopamine microspheres

Smart self-healing coatings containing stimuli-responsive materials have attracted tremendous interest recently due to their switchable and desirable functionalities with the changes of external environment. However, the fabrication of most smart self-healing coatings requires complex procedures and/or unfriendly chemicals, and the environmental durability of a coating is still considered as a major factor that influences its large-scale engineering applications. Herein, an eco-friendly smart self-healing coating with near infrared (NIR) and pH dual-responsive superhydrophobic and anti-biofouling properties was fabricated by simply mixing the biomimetic stimuli-responsive mesoporous polydopamine microspheres (polydimethylsiloxane-loaded mesoporous polydopamine microspheres, abbreviated as P-PDMS@MPDA MSPs) with waterborne resin and hydrophobic nanoparticles. The P-PDMS@MPDA MSPs were fabricated through an emulsion-induced interfacial anisotropic assembly strategy, followed by the abundant loading of hydrophobic PDMS. These biocompatible P-PDMS@MPDA MSPs with NIR and pH dual-responsive properties acted as the self-healing agents and green hydrophobic fillers. The P-PDMS@MPDA MSPs also provided source for outfield stimulated response and no additional responsive material was required for the self-healing process. Superhydrophobicity of the coating was achieved with these fluorine-free, non-toxic, and biocompatible materials. When damaged by the external environment, the coating could directly self-heal its superhydrophobicity and active anti-biofouling properties under the NIR or pH stimuli, owing to the release of low-surface-energy PDMS from the P-PDMS@MPDA MSPs. The cytotoxicity of the casting solution for this smart coating and the long-term self-healing superhydrophobicity of the coating in harsh environments, including exposure to UV irradiation and immersion in salt, strong acid, and strong base solutions, were investigated. This smart coating shows great promise for anti-fouling, anti-adhesion, and biomedical applications due to its excellent self-healing and biological properties. The MPDA-based stimuli-responsive microspheres can be extended to other functionalized smart coatings.

Natural Highly-hydrophobic urushiol@TiO2 coated cotton fabric for effective oil–water separation in highly acidic alkaline and salty environment

A natural acid-alkali-salt resistant urushiol@TiO2 coated cotton fabric with a high water contact angle of 146.1 ± 0.3° was designed employing a facial immersion method. The as-prepared urushiol@TiO2 coated cotton not only has excellent stability toward UV irradiation and high temperature, but also exhibits great resistance to mechanical abrasion and acid-base solutions with various pH values. More importantly, while the pristine cotton fabric was penetrated and even destroyed by acid or base solutions immediately, the urushiol @TiO2 structures protected the coated cotton from penetration by high acid (10 M H2SO4 for 70 min and 1 M H2SO4 for more than 18 h) and high base (10 M NaOH for 70 min and 1 M NaOH for more than 18 h) solutions. The sharp contract indicates the potential of urushiol@TiO2 coated fabric to be used in some extreme conditions. Therefore, the as-prepared urushiol@TiO2 coated fabric was found to not only act as a high performance filter to separate oil–water mixtures with superior reusability, but also retain high separation efficiency separating oil–water mixtures in highly acidic (10 M H2SO4), alkaline (10 M NaOH), and salty (saturated NaCl) environments, as well as oil-in-water and water-in-oil emulsions. The modified fabric is environmentally friendly, and easy to fabricate with low cost, offering promising potential applications in resolving the serious issues of oily wastewater treatment and anti-corrosion protection.

Microemulsion Formulations with Tunable Displacement Mechanisms for Heavy Oil Reservoirs

Summary Waterflooding of heavy oil reservoirs is commonly used to enhance their productivity. However, preferential pathways are quickly developed in the reservoir because of the significant difference in viscosity between water and heavy oil and, hence, the oil is trapped. Here, we propose a platform for designing ultralow interfacial tension (IFT) solutions for reducing the capillary pressure and mobilizing the heavy oil. In this study, we formulated mixtures of organic acids and bases. We tested three different formulations: an ionic liquid (IL) formulation in which the bulk acid [4-dodecylbenzene sulfonic acid (DBSA)] and base [tetra-N-butylammonium hydroxide (N4444OH)] were mixed using general protocols for IL synthesis; an acid/base solution (ABS) in which the acid (DBSA) and base (N4444OH) were mixed in low weight fractions directly in water; and an acid salt/base solution (ASBS) in which the acid salt [sodium dodecylbenzene sulfonate (SDBS)] was used instead of the acid. All the formulations have a 1:1 stoichiometric ratio of acid and base. Salinity scans were conducted to determine the optimum salinity that gives the lowest IFT for each formulation. Corefloods were conducted in hydrophilic and hydrophobic sandpacks to evaluate the three formulations at their optimum salinities for post-waterflood heavy oil recovery. The IL and ABS formulation are acidic solutions with a pH of approximately 3. The ASBS formulation is highly basic with a pH of approximately 12. None of the formulations salted out below 14 wt% of sodium chloride (NaCl), whereas the conventional surfactant, SDBS, precipitated at a salt concentration of less than 2 wt% of NaCl. The formulation solutions (1 wt%) have different optimum salinities: 2.5 wt% NaCl for ASBS and 3 wt% NaCl for IL and ABS. Although the IL and ABS have the same composition and molar ratio of the components, their performances are completely different, indicating different intermolecular interactions in both formulations. Corefloods were conducted using sandpack saturated with Luseland heavy oil (∼15,000 cp) and a fixed Darcy velocity of 12 ft/D. A slug of 1 pore volume (PV) of each formulation was injected after waterflooding for 5 PV followed by 5 PV post-waterflooding. In the hydrophilic sandpacks, IL and ABS formulation produced an oil bank consisting mainly of a water-in-oil (W/O) emulsion, with oil recovery that was 1.7 times what was recovered by 11 PV of waterflooding solely. The majority of the oil was recovered in the 2 PV of waterflood after the IL slug. ASBS formulations produced oil-in-water (O/W) emulsions with prolonged recovery over 5 PV waterflooding after the ASBS slug. The recovery factor for ASBS was 1.6 times that recovered for 11 PV of waterflooding only. In the hydrophobic sandpacks, the ASBS formulation slightly increased the recovery factor compared with only waterflooding, whereas for IL and ABS formulations, the recovery factor decreased. In this work, we present a novel platform for tuning the recovery factor and the timescale of the recovery of heavy oil with a variable emulsion type from O/W to W/O depending on the intermolecular interactions in the system. The results demonstrate that the designed low IFT solutions can effectively reduce the capillary force and are attractive for field applications.

The assessment of predict-observe-explain (POE)-based chemistry high school teacher’s supporting book for reaction rate, acid base solution, and colloidal system

This research aimed to identify the quality of the developed teacher’s supporting book which is the POE demonstration for reaction rate, acid base solution, and colloidal system based on the assessment from experts. The assessing experts consisted of a content expert, a learning expert, and a media expert. The content expert assessed the book based on the feasibility of the content component. The learning expert assessed the book based on the feasibility of the presentation component. The media expert assessed the book based on the feasibility of the readability (language and image) and the graphic components. Based on the results of the expert’s assessments, it can be seen that the quality of the book in terms of the material or content components was categorised as ‘very good’, the presentation component was categorised ‘very good’, the readability component (language and image) was categorised as ‘good’, and the graphic component was categorised as ‘good’. Overall, the quality of the developed books was categorised as ‘very good’, so that it is feasible to be teacher’s supporting book in demonstrating chemistry materials for reaction rate, acid base solution, and colloidal system based on POE strategy.

An efficient strategy for improving the water stability of a nearinfrared- emissive lanthanide MOF

Near-Infrared-emissive materials have attracted substantial attention due to their unique properties. To solve the urgent requirements of high-water stability materials can be widely used in practical engineering. Hence, a novel near infrared luminescent and highly water-stable lanthanide-organic frameworks (namely Yb-MOF-Y) was synthesized under hydrothermal method by anchoring functionalized, rigid ligands 2,3,5,6-tetrafluoroterephthalic acid and 1,10-phenanthroline onto its skeleton. It is notable that the Yb-MOF-Y possess high structural stability in water for 28 days, in different acid-base solutions (pH = 4-10) for 3 days and the thermal stability in water (-20 °C to 60 °C) for 3 days. Remarkably, luminescent studies reveal that the Yb-MOF-Y can be used as a potential material in near infrared field.

Study on the influence of test solution concentration on the chemical corrosion resistance of ceramic tiles

Chemical resistance is one of the important evaluation factors of ceramic tiles. This article describes the method for determining the chemical resistance of ceramic tiles, and discusses the influence of acid-base solution concentration on the test results during the experiment, and proposes corresponding improvement measures.

Effect of acid-base corrosion on the tensile strength of shale under different temperature

In this study, we mainly investigate the impact of the acid-base corrosion on the tensile strength of the shale under different concentration and water bath temperature of acid-base solutions. Based on the X-ray diffractometry, the SEM and Brazilian splitting tests, the changes of the composition, macro-surface morphology, micro-structure and tensile strength of shale before and after acid-base corrosion are systematically analyzed. The results show that acid-base corrosion would cause chemical damage to shale as a result of the removal of the high hardness minerals and the generation of the dissolved pores and microfractures, resulting in the reduction in its tensile strength. Meanwhile, higher concentration and water bath temperature can promote acid- or alkali-shale interactions and increase the weakening degree of the shale tensile strength.

The influence of acid and base solutions on the quenching process against the hardness of ST37 steel

Previous research stated that salt water cooling media has higher hardness value after going through the heat treatment process compared to freshwater cooling media. From this explanation, a study was conducted on the effect of using acid and alkaline solutions in the quenching process against the hardness of ST37 steel. This study uses vinegar water cooling media and soapy water. In this study several steps were carried out, namely: hardening on ST37 steel with a heating temperature of 700ºC with a holding time of 15 minutes, direct quenching with acidic cooling media (vinegar: 2.4 pH) and alkaline solution (soap water: 9.3 pH ) with a 15 minute holding time. After the heat treatment process and direct quenching on ST37 steel, Rockwell hardness was tested. From the test results, the use of acid and base solution cooling media in the quenching process has an effect on the hardness of ST37 steel, the best hardness value is an alkaline solution compared to an acid solution, alkaline solution has a hard value of 66.73 HRC, while acid solution has a hardness value of 64.31 HRC. The results of this study will be one of the references for further research, especially the use of weak acid-base solutions as a cooling medium.

In Vitro Effect of Gallium-Doped Bioactive Glass on Enamel Anti-Demineralization and Bond Strength of Orthodontic Resins

White spot lesions (WSL) that occur on teeth after orthodontic appliances have been attached are caused by bacterial demineralization of the enamel surface. This study investigated the anti-demineralization effect of orthodontic resins containing mesoporous bioactive glass nanoparticles (MBN) doped with gallium, which has antibacterial activity, as well as MBN with increased calcium and phosphate contents as these ions can remineralize enamel. Resins (CF, CharmFill Flow, Dentkist, Seoul, South Korea) containing 1%, 3%, and 5% Ga-doped MBN (GaMBN) were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and isothermal tests, and their physical properties were measured in terms of Vickers microhardness, bracket retention force, and adhesive remnant index (ARI). Cell viability in the resins was confirmed by testing human dental pulp stem cells (hDPSCs), and ion release tests were performed after 1, 7, and 14 days to determine whether the resins released Ga3+, Ca2+, and PO43–. After 14 days, antibacterial activity was determined using Streptococcus mutans (S. mutans)—the bacteria that causes tooth decay—and the chemical remineralization effect was investigated using a cycle of acid–base solutions. The microhardness of the resins increased with GaMBN concentration whereas their bracket retention force, ARI, and cell viability remained unchanged. The bacterial activity of the 5%-GaMBN resin decreased after 24 and 48 h; however, the change in activity was not statistically significant. Anti-demineralization testing demonstrated that the degree of enamel demineralization decreased as the GaMBN concentration increased, which indicates that resins containing 5%-GaMBN may be viable orthodontic adhesives for preventing WSLs.

Mechanisms of chloride and sulfate removal from municipal-solid-waste-incineration fly ash (MSWI FA): Effect of acid-base solutions

A general approach to managing municipal solid waste is by incineration. Unfortunately, large amounts of municipal-solid-waste-incineration fly ash (MSWI FA) is produced in the process, with their heavy metals content posing further problems to the environment. One fundamental treatment of MSWI FA heavy metals is called solidification-stabilization, where MSWI FA is solidified in cement-based materials to cap hazardous elements from being released into the environment. Mortar formed from this cement mixed with MSWI FA suffer from decreased compressive strength due to their chloride and sulfate contents. Thus, pre-treatment of MSWI FA to remove these salts before producing mortar is desirable. This study investigated treating MSWI FA with deionized water, 0.01 M and 0.1 M nitric acid, and 0.1 M and 0.25 M sodium carbonate to remove chloride and sulfate. Physical and chemical structures of treated and untreated MSWI FA was studied to understand the chloride and sulfate removal mechanisms. Treated MSWI FA was used as cement replacement in mortar, and the compressive strength was tested. Results suggest that all of the treatment solutions tested in this study can equally remove chloride (around 250,000 mg/kg), but sodium carbonate can remove sulfate at the highest extent (15,821 mg/kg). In addition, mortar with deionized-water-treated MSWI FA gave the highest compressive strength. Heavy metals leaching was tested by the Toxicity Characterization Leaching Procedure (TCLP) method, with results passing the standard.

Novel Multifunctional Zn Metal–Organic Framework Fluorescent Probe Demonstrating Unique Sensitivity and Selectivity for Detection of PA and Fe3+ Ions in Water Solution

A novel metal–organic framework {Zn2(tpt)2(tad)2·H2O} (tpt = 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine, H2tda = 2,5-thiophene dicarboxylic acid) with a 3-fold interpenetrating 3D framework was successfully synthesized under hydrothermal conditions. As expected, 1 displays excellent luminescence and can stably exist in different pure organic solvents and acid–base solution. 1 can be considered as an ultrasensitive sensor for detection of Fe3+ ions and PA with high selectivity by fluorescence quenching behaviors. Meanwhile, the fluorescence test plates show the visible color change of Fe3+ ions which can be easily observed by the naked eye in the detection process, which makes Fe3+ ions more easily recognized than various metal ions. In addition, the mechanism of fluorescence quenching is also further discussed.

Etching-free template synthesis of double-shelled hollow SiO2@SnO2@C composite as high performance lithium-ion battery anode

With merits such as ease of preparation and adjustable morphology, SiO2 is commonly used as a sacrifice template to prepare hollow SnO2-based composite anode materials for lithium-ion batteries. However, the following removal of SiO2 template often involves the use of highly corrosive solvents such as hydrofluoric acid and strong base solution, which is detrimental to the health of the experimenters, and the environment, thus needs to be avoided. Herein, a double-shelled hollow SiO2@SnO2@C composite has been synthesized by using prefabricated hollow SiO2 spheres as template but not be removed, thereby avoiding the use of strong corrosive solvents. Moreover, the as-prepared SiO2@SnO2@C composite demonstrates outstanding electrochemical lithium storage performances when examined as a lithium-ion battery anode material (high reversible capacities of 923 and 538 mAh g−1 are remained after 340 and even 1000 cycles at 200 and 1000 mA g−1 respectively), and even better than those of reported state-of-the-art SnO2/C composites. Thus, it is suggested that this work may offer a new viewpoint to the preparation of advanced SnO2-based anodes with adjustable structures by facile etching-free SiO2 template assisted approaches. This concept mentioned here may also be extended to preparation of other hybrid anode materials capable of withstanding drastic volume variation.

Analysis of Chemical Representation in Chemical Text Books Class XI High School in the Materials of Acid Base Solutions

Abstract - Textbooks are reference books for certain subjects that are used by students and educators to facilitate the learning process. The material in the textbook must be in accordance with the competencies achieved in the curriculum and the material must also be accurate to avoid misconceptions. One way to assess textbooks is to analyze them. This study aims to describe the results of chemical representation analysis in chemistry textbooks of class XI SMA in the chapter material on acid-base solutions compared to standard textbooks. The data sources in this study are 2 chemical textbooks, namely Unggul Sudarmo (Book A) and written by Tine Maria Kuswati (Book B) and the standard textbook used as a reference is Chemistry the Molecular Nature of Matter by James E. Brady. Criteria that can be used to analyze chemical representations and the relationship between representations are the methods proposed by Gkitzia et al. (2010). This method has 5 criteria: (C1) Type of representation, (C2) Interpretation of surface features, (C3) Relatedness to text, (C4) Existence and properties of a caption, (C5) Degree of correlationbetween representations comprising a multiple one The findings of this study indicate that the representation in Book A only fulfills 3 Gkitzia criteria, while Book B satisfies all Gkitzia criteria and corresponds to the representation that appears in the standard Brady textbook.