2al 3br2 2albr3 what type of reaction is this

3.00 mol of O2 at STP occupies how much volume? Answer: a {eq}2\text A\text l + 3\text B\text r_2 \rightarrow 2\text {AlBr}_3 {/eq} This is a balanced redox reaction equation. none of these. Chemistry >. True or false, and why? substitutue 1 for any solids/liquids, and P, rate = -1/2 * ([Al] / t) = -1/3 * ([Br, (assuming constant volume in a closed system and no accumulation of intermediates or side products). D. There is more likely to be an earthquake in a "highest hazard" location than in a "lowest hazard" location. Balance the redox reaction accordingly. Write your answer on the space before the number. The gas phase consists of air with dynamic viscosity (g)\left(\mu_{g}\right)(g) of 18.4106kg/ms,18.4 \times 10^{6} kg/m \cdot s,18.4106kg/ms, density (g)(\rho_g)(g) of 1.19kg/m3,1.19 kg/m^3,1.19kg/m3, and Prandtl number (Prg)(Pr_g)(Prg) of 0.71. The algebraic method is likely better suited for balancing this equation. Al2S3 The effect is enhanced by red bromine fumes present in the reaction container. 6 This would mean that the hydrogen gas is the limiting reactant and would dictate the theoretical . The total number of stars for this article is: What are the chemical and physical characteristic of Al (aluminium)? Compound states [like (s) (aq) or (g)] are not required. Find the constants BBB and CCC in Andrade's equation for water, if it has been experimentally determined that =1.00(103)Ns/m2\mu=1.00\left(10^{-3}\right) \mathrm{N} \cdot \mathrm{s} / \mathrm{m}^2=1.00(103)Ns/m2 at a temperature of 20C20^{\circ} \mathrm{C}20C and that =0.554(103)Ns/m2\mu=0.554\left(10^{-3}\right) \mathrm{N} \cdot \mathrm{s} / \mathrm{m}^2=0.554(103)Ns/m2 at 50C50^{\circ} \mathrm{C}50C. combustion Replace the petri dish on top of the container. 2H+ + 2e- arrow H2. Explain. HNO3(aq) + KOH(aq) KNO3(aq) +H2O(l) Chemical Equation Balancer . . You can use parenthesis () or brackets []. Which type of reaction is represented by the following equation? Cu(OH)2 Fe2(SO4)3 Fe^3+ + NO2^- + H2O arrow Fe^2+ + H^+ + NO3^-. 1 To balance a chemical equation, enter an equation of a chemical reaction and press the Balance button. Al2S3 Privacy Legal & Trademarks Campus Map, Lecture Demonstration Manual General Chemistry, S124: Chemical Rxns Synthesis 2Al(s) + 3Br2(l) 2AlBr3(s), S115: Stoichiometry Limiting Reagents : Mg + HCl, S120: Chemical Rxns Synthesis & Decomposition Zn & I2, S128: Chemical Rxns Synthesis 2Al(s) + 3I2(s) 2AlI3(s), S130: Chemical Rxns Precipitation CaCl2 + Na2CO3 -> CaCO3, S135: Chemical Rxns Precipitation Pb(NO3)2 + KI PbI2(s), S140: Chemical Rxns Combustion H2 and He Balloon Explosions, S145: Chemical Rxns Combustion The Exploding H2 Bottle or Hydrogen Cone, S150: Chemical Rxns Crystallization Saturated Sodium Acetate, S160: Chemical Rxns Dehydration Dehydration of Sugar, S170: Chemical Rxns Complex Ions Invisible Signs, S180: Nomenclature Demonstration of Common Compounds, S190: Chemical Rxns Removing the Iron from Total Cereal. Br2(l) + 2K(s) arrow KBr(s), Determine whether or not the following equation represents a redox reaction. 2AlBr3 2Al + 3Br2. NO3-(aq) AlBr3 is oxidized and Al is reduced. 3) Answer is: Br2 is the oxidizing agent because its oxidation number decreases. Fe2+(aq) + N2(g) arrow Fe3+(aq) + N2H4(aq), Balance the following redox reaction in basic solution: H2O2 + ClO2 arrow ClO-2 + O2, Determine whether or not the following reaction is an oxidation-reduction reaction. What type of reaction is the following? La ecuacin balanceada aparecer arriba. Reaction is in the state of balance when Each type of atoms in both reactant and product side are . Determine the flow depth and velocity before the jump, and the fraction of mechanical energy dissipated. (select all that apply) 2CH3OH(l) + 3O2(g) arrow 2CO2(g) + 4H2O(l) a. combination b. single replacement c. double replacement d. decomposition e. precipitation f. combustion g. acid-base, Classify the following reaction: 3Fe(s) + 4H2O(g) arrow Fe3O4(s) + 4H2(g) a. combination b. decomposition c. single displacement d. double displacement, Classify the following reaction: 2Fe2O3(s) + 3C(s) arrow 4Fe(s) + 3CO2(g) a. combination b. decomposition c. single displacement d. double displacement, Classify the following reaction: MgI2(ag) + Pb(NO3)2(aq) arrow Mg(NO3)2(ag) + PbI2(s) (select all that apply) a. combination b. precipitation c. single replacement d. double replacement e. combustion f. acid-base g. decomposition, Classify the following reaction: KOH(aq) + HClO4(aq) arrow KClO4(aq) + H2O(l) (select all that apply) a. combination b. precipitation c. single replacement d. double replacement e. combustion f. acid-base g. decomposition, Classify the following reaction: 2HgO(s) arrow 2Hg(l) + O2(g) a. decomposition b. combination c. double displacement d. single displacement, Classify the following reaction: 2KClO3(s) arrow 2KCl(s) + 3O2(g) a. decomposition b. combination c. double displacement d. single displacement, Classify the following reaction: 4Fe(s) + 3O2(s) arrow 2Fe2O3(s) a. decomposition b. combination c. double displacement d. single displacement, Classify the following reaction: S8(s) + 8O2(s) arrow 8SO2(g) a. decomposition b. combination c. double displacement d. single displacement, Classify the following reaction: Mg3N2(s) + 6H2O(l) arrow 3Mg(OH)2(aq) + 2NH3(g) a. decomposition b. combination c. double displacement d. single displacement, Classify the following reaction: 3Mg(s) + N2(g) arrow Mg3N2(s) a. decomposition b. combination c. double displacement d. single displacement, For the reaction below, classify as a combination, decomposition, single replacement, or double replacement. (b) Graph N(t) as a function of t on a semilog plot, and determine the slope of the resulting straight line. If it were instead $\ce {Al2Br6}$, that would indicate a different formula unit - it would imply a different compound. IV. A. the distance from the epicenter of an earthquake b. acid 2AgBr(s) arrow 2Ag(s) + Br2(g), Classify the following reaction: Ba(ClO3)2 arrow BaCl2 + 3O2 a. combination b. decomposition c. single replacement d. double replacement, Classify the following reaction: Pb(NO3)2(aq) + KI(aq) arrow PbI2(s) + KNO3(aq) a. combination b. decomposition c. single replacement d. double replacement, Classify the following reaction: Pb(NO3)2(aq) + CaCl2(aq) arrow PbCl2(s) + Ca(NO3)2(aq) a. combination b. decomposition c. single replacement d. double replacement, Classify the following reaction: ZnSO4 + Mg arrow Zn + MgSO4 a. combination b. decomposition c. single replacement d. double replacement, Classify the following reaction: Ba(ClO3)2 arrow BaCl2 + 3O2 a. combination (synthesis) b. decomposition c. displacement (single replacement) d. exchange (double replacement), Classify the following reaction: (NH4)2CO3(s) arrow CO2(g) + NH3(g) + H2O(g) a. combination b. decomposition c. single replacement d. double replacement, Classify the following reaction: Zn + 2HCl = ZnCl2 + H2 Select one: a. decomposition b. combination c. none of above d. double replacement e. single replacement, Classify the following reaction: Mg(OH)2(s) + HCl(aq) arrow MgCl2(aq) + HOH(g) a. combination b. decomposition c. single replacement d. double replacement, For the reaction below, classify as a combination, decomposition, single replacement, or double replacement. K2SO4 oxidation-reduction The equation 2Al(s) + 3Br2(l) 2AlBr3(s) is a(n) ______________ reaction. 2NH4+(aq) hydrochloric acid Ca2+(aq) Determine the net ionic equation. CO2, Which of the following is a correct mole ratio for the following equation? Balanced chemical reaction: 2Al + 3Br 2AlBr. 4 We could not determine all the steps needed to balance the equation using trial and error. precipitation C6H12O6(s) arrow CO2(g) + C2H5OH(l), Is the following unbalanced reaction a redox-reaction or a non-redox reaction? Can you determine the type of reaction if you see the entire balanced equation? 2AlBr3 2Al + 3Br2. The amount of product that can be produced from a given amount of reactants based on stoichiometric calculations is: You calculate the theoretical yield of a chemical reaction starting with 50.0g of reactant is 25.0g of product. What are the chemical reactions that have Br2 (bromine) as prduct. 2KNO3, Which of the following ionic compounds is insoluble in water? The equation 2C2H6 + 7O2 4CO2 + 6H2O is an oxidation-reduction reaction. a.\ 2Fe_{2}O_{3}\rightarrow 4Fe+3O_{2} [{Blank}] b.\ Cu(NO_{3, Consider the following balanced chemical reaction: 2C8H10 + 21O2 arrow 16CO2 + 10H2O. transfer of electrons What is the theoretical yield of Znl2, if 1.912 mol of zinc is used? Para balancear una ecuacin qumica, ingresa la ecuacin de una reaccin qumica y pulsa el botn de Balancear. BaCO3 . Aluminum bromide is produced by the reaction of aluminum metal with bromine liquid, according to the following balanced equation: 2 Al (s) + 3 Br2 (l) 2 AlBr3 (aq) If 10.0 grams of Al is added to 10.0 g of Br2, assuming the reaction has yielded 100% yield, calculate the mass (in grams) of . manufacturing The given reaction is the manufacturing or synthesis reaction. 3 mol Br2 : 2 mol Al C. 2 mol AlBr3 : 1 mol Br2 D. 2 mol Br : 2 mol Al 10. KNO3 Explain. Cu2S, The equation 2Ag2O(s) 4Ag(s) + O2(g) is a(n) ______________ reaction. 4 Not all answers will be used. You can specify conditions of storing and accessing cookies in your browser, Which statement best identifies and describes the oxidizing agent in the reaction? H_2CO_3(aq) to CO_2(g) + H_2O(I), For the reaction below, classify as a combination, decomposition, single replacement, or double replacement. The following are high-spin complexes. (A) O (B) 1 (C) 2 (D) Some other order 2. D. the total amount of energy released by an earthquake. CuSO4 CaCO3 Two substances have the same percent by mass composition, but very different properties. In a synthesis reaction, two or more substances combine to form a new compound. Aluminium in form of powder. An aqueous solution of ammonium carbonate is allowed to react with an aqueous solution of barium chloride. If we use this reaction in the video as an example, lets say they give 65.0 grams of hydrogen gas but say that we have an excess of carbon monoxide. Ejemplos: Fe, Au, Co, Br, C, O, N, F. Las cargas inicas an no son . -algia, On the basis of the general solubility rules given in Table 7.1, predict which of the following substances are likely to be soluble in water. Simple Decomposition (NH4)2SO4 + 2HCl 2NH4Cl + H2SO4. 2AgNO3(aq) + Mg(s) arrow Mg(NO3)2(aq) + 2Ag(s) Identify the type of reaction shown in the following chemical equation. Answers >. What is the excess reactant in the following reaction if you start with 50.0g of each reactant? Get access to this video and our entire Q&A library. 2 See Answer See Answer See Answer done loading. Magnitude measures the duration of the earthquake, while intensity measures the amount of damage. Question Which of the following is a correct mole ratio for the following equation? The two-phase flow has flow quality (x) of 2.08105,2.08 \times 10^{5},2.08105, void fraction ()(\alpha)() of 0.011, gas velocity (Vg)(V_g)(Vg) of 13.5 m/s, liquid velocity (Vl)(V_l)(Vl) of 9.34 m/s, and liquid mass flow rate (ml)\left(\dot{m}_{l}\right)(ml) of 0.907 kg/s. Al + NiBr2 = AlBr3 + Ni might be a redox reaction. Zinc reacts with iodine in a synthesis reaction: Zn + I2 Znl2. What is the mass, in kilograms, of a liter of water? 2Al + 3 Br 2 2 AlBr 3 A) Al is oxidized and Br 2 is reduced. Find another reaction Thermodynamic properties of substances The solubility of the substances Periodic table of elements Picture of reaction: oding to search: 2 Al + 3 Br2 = 2 AlBr3 The reactant or reacting species are defined as such chemical species which undergo consumption during the reaction to produce new species (products). Identify the solid in the balanced equation. Na2S This step may be repeated until one of the reagents is exhausted. What type of reaction is 2AlCl3 2Al s 3Cl2 G? True; the oxygen is reduced, and the hydrogen is oxidized. To identify the oxidized and reduced species we need to consider changes in oxidation states of the elements. Aluminum dust added to finely ground I 2 produces heat and copious purple vapor upon the addition of water. about lifestyle changes that he could make immediately to help with his situation. Determine whether or not the reaction is a redox reaction: Cu(s) + 2AgC2H3O2(aq) arrow Cu(C2H3O2)2(aq) + 2Ag(s), Determine whether or not the reaction is a redox reaction: 2LiClO3(s) arrow 2LiCl(s) + 3O2(g), Determine whether or not the reaction is a redox reaction: 3H2SO4(aq) + 2Al(OH)3 arrow Al2(SO4)3(aq) + 6H2O(l), Determine whether or not the reaction is a redox reaction: Pb(NO3)2(aq) + 2LiCl(aq) arrow PbCl2(s) + 2LiNO3(aq), Determine whether or not the reaction is a redox reaction: 4Co(s) + 3O2(s) arrow 2Co2O3(s), Determine whether or not the following reaction is a redox reaction. Zn(OH)2(aq) + H2SO4(aq) arrow ZnSO4(aq) + 2H2O(l), Determine whether or not the following equation represents a redox reaction. (NH4)2CO3 You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Which is the empirical formula for hydrogen peroxide? How many mol of hydrogen gas are required to react with 1.50 mol oxygen gas in the following reaction? Balance the equation Al + NiBr2 = AlBr3 + Ni using the algebraic method or linear algebra with steps. Lora Ruffin and Michael Polk, Summer 2009, University of Colorado Boulder Regents of the University of Colorado How are P waves different from S waves? Chemical Equation Balancer; Reaction Stoichiometry Calculator; What is the correct classification for the reaction 2PbSO4 arrow 2PbSO3 + O2? decomposition What are the chemical and physical characteristic of Br2 (bromine)? The ____ is the maximum amount of product that can be produced from a given amount of reactant. If a metric ton of water were held in a thin-walled cubical tank, how long (in meters) would each side of the tank be. How do you determine if 2Ag2O(s) arrow 4Ag(s) + O2(g) is a redox reaction? B. the vibrations produced by an earthquake 2Al(s) + 3Br2(l) 2AlBr3(s) A. A metal-nonmetal reaction involves electron transfer. How many atoms of hydrogen are in 3.5 mol of H2S? 4H2(g) + O2(g) 2H2O(l) A. 3O2 + 4Al 2Al2O3. synthesis, Which of the following ionic compounds is soluble in water? Types Of Chemical Reaction. 2CrO42- + 2H+ arrow Cr2O72- + H2O, Determine whether the following reaction involves oxidation and reduction. To balance a chemical equation, enter an equation of a chemical reaction and press the Balance button. Na+(aq) If two variables are directly proportional, what happens to the value of one as the other decreases? Cr(OH)4- (aq) + ClO- (aq) arrow CrO42- (aq) + Cl- (aq). A two-phase flow mixture of air and silicone (Dow Corning 200 Fluid, 5 cs) is being transported in an 11.7-mm-diameter thin-walled horizontal tube. III. V. decomposition, Classify the following reaction: KIO3(aq) + KI(aq) + H2SO4(aq) arrow K2SO4(aq) + H2O(l) + I2(s), Determine whether or not the following reaction is an oxidation-reduction reaction. What is the oxidizing agent in the reaction? Calculators. MgI2(aq) + 2NaOH(aq) arrow Mg(OH)2(s) + 2NaI(aq), Determine whether or not the following equation represents a redox reaction. Ba2+ and NO3- You'll get a detailed solution from a subject matter expert that helps you learn core concepts. 2NaHCO3 Na2CO + CO2 + H2O. KCl An earthquake has a high magnitude but a low intensity. Ba2+ and NO3- PbSO4, Which of the following will be spectator ions in the reaction in aqueous solution of barium nitrate and potassium phosphate? none of these, CH4(g) + 2O2(g) CO2(g) + 2H2O(g) An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. precipitation NaNO3 There are two types of electronic signals: analog and digital. 2H2 + O2 -->2H2O Lithium reacts with nitrogen to form lithium nitride. CaS Question #115914. What is the oxidizing agent in the following redox reaction? ClO3- + Cl- arrow Cl2 + ClO2-, What is the equation for the redox reaction involving the following 2 equations? molarity. For these types of problems, I like to write out all . The viscosity of a liquid will increase as: The addition of energy to water molecules will cause them to ____. CuO + 2HCl -----> CuCl2 + H2O _____6. a. K2S Al + Br2 = AlBr3 might be a redox reaction. Question: the reaction 2Al+3Br2> 2AlBr3 is an example of a. 2SO42-(aq) Synthesis. The Chlorine is reduced from oxidation state 0 . Determine whether or not the following reaction is an example of a redox equation. Pb(NO3)2(aq) + 2HCl(aq) arrow PbCl2(s) + 2HNO3(aq), Balance the redox reaction: I2 + HNO3 arrow HIO3 + NO2 + H2O, Balance the following redox reaction: HNO3 + H2S arrow NO + S + H2O, Which equation describes a redox reaction? are left dissolved in the solution Determine whether the following reaction involves oxidation and reduction. 2Al(s) + 3H2SO4(aq) arrow Al2(SO4)3(aq) + 3H2(g) b. Ba(NO3)2(aq) + K2CrO4(aq) arrow BaCrO4(s) + 2KNO3(aq), Classify the following as a combination, decomposition, single replacement, double replacement, or combustion reaction. How are the waveforms similar? Ba2+ and PO43- If you would like to attempt to guess the next steps, the final element counts in the balanced equation should be: Scroll down to see reaction info, how-to steps or balance another equation. synthesis NaCl(s), Which of the following is a strong acid? At a given temperature, the solubility of a gas is directly proportional to what? b. 3Pb2+(aq) Determine the number of unpaired electrons, if any, in each.\, K4[FeF6]\mathrm{K}_4\left[\mathrm{FeF}_6\right] 2Al + 3Br2 2AlBr3 Al is the oxidizing agent because its oxidation number increases. When dispersed solids in a colloid scatter light, it is known as ____. 2Li(s) + 2H_2O(I) to 2LiOH(aq) + H_2(g), For the reaction below, classify as a combination, decomposition, single replacement, or double replacement. 2Al (s)+3Br2 (g) 2AlBr3 (s) Classify as a combination, decomposition, single replacement, double replacement, or combustion reaction: Expert's answer. Balanced chemical reaction: 2Al + 3Br 2AlBr. Zn(s) + CuCl2(aq) arrow Cu(s) + ZnCl2(aq). KNO3(aq) + HCl(aq) arrow KCl(aq) + HNO3(aq), Is the following reaction a redox reaction? Examples: Hydrogen reacts with oxygen to form water. Pour about 7 pieces of aluminum foil into the beaker. two of these, An aqueous solution of sodium sulfide is allowed to react with an aqueous solution of magnesium chloride. According to Charles's law, if pressure and amount of a gas are fixed, what will happen as volume is increased? The liquid phase consists of liquid silicone with surface tension ()(\sigma)() of 19.7103N/m,19.7 \times 10^{3} N/m,19.7103N/m, dynamic viscosity (l)\left(\mu_{l}\right)(l) of 45.7104kg/ms,45.7 \times 10^{4} kg/m \cdot s,45.7104kg/ms, density (l)(\rho_l)(l) of 913kg/m3,913 kg/m^3,913kg/m3, thermal conductivity (kl)(k_l)(kl) of 0.117W/mK,0.117 W/m \cdot K,0.117W/mK, and Prandtl number (Prl)(Pr_l)(Prl) of 64. Cu2CO3. Mg(s) + 2AgNO3(aq) arrow Mg(NO3)2(aq) + 2Ag(s) a. single replacement b. double replacement c. synthesis d. decomposition, Which type of reaction is represented by the following equation? The following equation represents the reaction between aluminum (Al) and bromine (Br2) to produce aluminum bromide (AlBr3): 2Al + 3Br2 2AlBr3 If I try to react 15 grams of aluminum (Al) with 15 grams of bromine (Br2), use your answer from the above question (25) to calculate mass in grams of the . Determine whether the reaction is a redox reaction. Ag+, K+, Cl-, and NO3- 2Na+ Al2(CO3)3 Rating: 5 / 5 stars. Fe3O4(s) + CO(g) arrow FeO(s) + CO2(g), Determine whether the following reaction is a redox reaction. 2Al + 3Br2 -----> 2AlBr3 Types of Chemical Reactions Determine what types of chemical reactions are the equation undergo. SO3(g) + H2O(l) arrow H2SO4(aq). Cu2CO3, Which of the following ionic compounds is insoluble in water? C. the amount of damage that results from an earthquake CH4 + 4O2- arrow CO2 + 2H2O + 8e-, Determine whether the following reaction is an oxidation reaction or a reduction reaction. Suppose that N(t) denotes a population size at time t and satisfies the equation N(t)=2e3tfort0N(t)=2 e^{3 t} \quad \text { for } t \geq 0N(t)=2e3tfort0 (a) If you graph N(t) as a function of t on a semilog plot, a straight line results. Smith, Michael Abbott, Bruce Edward Bursten, Catherine J. Murphy, H. Eugene Lemay, Matthew E. Stoltzfus, Patrick Woodward, Theodore E. Brown. single replacement reaction. Place finely ground iodine crystals and aluminum dust in the evaporating dish and mix with a stirring rod. 6, When the following equation is balanced, what is the coefficient for H2O? 2 mol Al : 3 mol Br B. 2KBr(aq) + Pb(NO3)2(aq) arrow 2KNO3(aq) + PbBr2(s) c. CaBr2(aq) + H2SO4(aq) arrow CaSO4(s) + 2HBr(g) d. H+(aq) + OH-(aq) arrow H2O(l) e. CO32-(aq) + HSO4-(aq. The total number of stars for this article is: 5 in 1 review. CaSO4, An aqueous solution of sodium carbonate is allowed to react with an aqueous solution of magnesium chloride. deconstructive synthesis single replacement double replacement and more. When two nonmetals react, the compound formed is ionic. Further questions related to chemical reactions 2Al + 3Br 2 2AlBr 3. As(s) + ClO3-(aq) arrow H3AsO3(aq) + HClO(aq), Balance the following redox reaction in acidic solution. 3. \\ 2 AlN \rightarrow 2Al + N_2 \\ A) combination B) decomposition C) single replacement D) double replacement E) combustion (assuming all reactants and products are aqueous. Which of the following ionic compounds is soluble in water? How many moles of Al are in 2.0 mol of Al2Br3? Which of the following ionic compounds is insoluble in water? For example, C6H5C2H5 + O2 = C6H5OH + CO2 + H2O will not be balanced, but XC2H5 + O2 = XOH + CO2 + H2O will. Read our article on how to balance chemical equations or ask for help in our chat. Provincial Exam Study Guide Unit 2: Chemical Reactions and Radioactivity Lionel Sandner Edvantage Press Ltd Sidney British Columbia Glen Fatkin North Surrey Secondary School 1 2 3 6, Which of the following is NOT one of the four types of reactions? Explain why this is a redox reaction. Magnitude measures the energy re 1/2O2 + H2O + 2e- arrow 2OH-, Which of the following reactions are redox reactions? Count the number of atoms of each element on each side of the equation and verify that all elements and electrons (if there are charges/ions) are balanced. Scroll down to see reaction info, how-to steps or balance another equation. Cl- hydrochloric acid 6Li + N2--> 2Li3N Aluminum reacts with bromine to form aluminum bromide.. 2H2(g) + O2(g) 2H2O(l). K+ and NO3- Balance Al + Br2 = AlBr3 by inspection or trial and error with steps. It's a redox reaction. combustion 3 You can use parenthesis () or brackets []. Balance the redox reaction: ClO3- + S2- arrow Cl- + S. Determine whether the following equation represents oxidation or reduction. the reaction 2Al+3Br2> 2AlBr3 is an example of a; This problem has been solved! Determine whether the reaction is a redox reaction.