balancing chemical equations with parentheses and coefficients

Source: www.tessshebaylo.com. So if we multiplied both sides by two, we're going to do that. 3) Indicate the states of matter of the reactants and products. A chemical reaction is the process by which one or more substances are changed into one or more new substances. The reason is that they usually appear in multiple reactants and products, so if you tackle them first you're usually making extra work for yourself. triangle indicates that the reaction is being heated. 4 Fe works, if you then add a coefficient of 2 in front of the rust (iron oxide) molecule, making it 2 Fe2O3. Coefficients One reason that our program is so strong is that our . A + sign separates two or more reactants or products. How is an equation written?Ans: A chemical equation consists of the chemical compounds represented by chemical formulas on the left that comprise the reactants and chemical compounds represented by chemical formulas that comprise the products. The inclusion of stoichiometric coefficients to the reactants and products is required to balance chemical equations. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Can the formula of an ionic compound contain two sets of parentheses? What condition must be met when writing a formula for an ionic compound? For example, right over Born and raised in the city of London, Alexander Johnson studied biology and chemistry in college and went on to earn a PhD in biochemistry. 1.1.7 Balancing oxygen. Step II: We must always start balancing with the compound that contains the maximum number of atoms either on the reactant or product sides. It decomposes to lime, nitrogen dioxide, and oxygen. Write an unbalanced equation, using the correct formulas for all reactants and products. This is crucial because a chemical equation must follow the laws of conservation of mass and constant proportions, which means that the reactant and product sides of the equation must have the same amount of atoms of WebBalance the following equation for this reaction of sucrose. A plus symbol \((+)\) separates the substances in the reactants and products. We also use third-party cookies that help us analyze and understand how you use this website. Balance any oxygen or hydrogen atoms last. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. you might notice that you don't have the same number Balance chemical formulas by placing coefficients in front of them. Adjust the coefficients to obtain the same number of atoms of this element (s) on both sides. To write the reaction, you need to identify the reactants (iron and oxygen) and the products (rust). H2O, so there are 2 hydrogen atoms and 1 oxygen atom (not 2 oxygen atoms). A coefficient is a whole number multiplier. Step 1: Make a Table. As a result, in the case above, the balanced equation is: \(3{\rm{Fe}}({\rm{s}}) + 4{{\rm{H}}_2}{\rm{O}}({\rm{g}}) \to {\rm{F}}{{\rm{e}}_3}{{\rm{O}}_4}(\;{\rm{s}}) + 4{{\rm{H}}_2}(\;{\rm{g}})\), The symbol (g) is used with \({{\rm{H}}_2}{\rm{O}}\) indicates that in this reaction, water is in the form of steam. ___ \(\ce{Mg(OH)_2} \left( aq \right) +\) ___ \(\ce{(NH_4)_2SO_4} \left( aq \right) \rightarrow\) 2 \(\ce{NH_4OH} \left( aq \right) +\) ___ \(\ce{MgSO_4} \left( s \right)\). Basically, you look at how many atoms you have on each side of the equation and add coefficients to the molecules to balance out the number of atoms. Step 1: Make a Table. The program accepts and solves problems with ion species. 3) 2: 3 x 2 x 1 = 6 O atoms . After many, many years, you will have some intuition for the physics you studied. This is a requirement based on the Law of conservation of mass. Remember, coefficients are the numbers that go in FRONT of a molecule. There are 4 Hydrogen atoms and 2 Oxygen atoms 2(H 2 ) = 4 Hydrogen atoms 2(O)= 2 Oxygen atoms RULE #2. This gives you: Iron is balanced, with 4 atoms of iron on each side of the equation. 1.5 times two is three. Use (aq) for species in solution in water. 1.1.1 Write down the given equation. Analytical cookies are used to understand how visitors interact with the website. Creative Commons Attribution/Non-Commercial/Share-Alike. These cookies ensure basic functionalities and security features of the website, anonymously. This website uses cookies to improve your experience while you navigate through the website. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Easy Steps for Balancing Chemical Equations, Add Coefficients To Balance Mass in a Chemical Equation. WebBalancing Chemical Equations with Interfering Coefficients Step 1: Take an inventory of the elements for each side of the equation. How do you count atoms with coefficients and subscripts? Step 2: Why is it necessary for nitrate to be in parentheses but it is not necessary for sulfate? Web3. aluminum and I add it to a dioxygen molecule, so a molecule that has two oxygens with it, under You may only add COEFFICIENTS when balancing chemical equations! This is now balanced, but if youre one of those students that doesnt like fractions in chemical equations, or the question asks for whole number coefficients, just multiply by the denominator ( i.e. Q.1. side, we have two aluminums. Conservation of Mass states mass isn't created or destroyed in a chemical reaction, so you need to add coefficients in front of the chemical formulas to adjust the number of atoms so they will be the same on both sides. By inspection (i.e., looking at it), you know you have to discard a coefficient of 2 for some higher number. How do you solve parentheses in chemistry? Yes! Two times two is four That's not the same color. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. the appropriate conditions they will react to form aluminum oxide. Among other questions, the program checks that formulation rules are not broken and that chemical elements, formulae and characters such as parentheses and subscripts are properly For instance , \({\text{CO}}\left( {\text{g}} \right){\text{ + 2}}{{\text{H}}_{\text{2}}}\left( {\text{g}} \right)\xrightarrow{{{\text{340}}\,{\text{atm}}}}{\text{C}}{{\text{H}}_{\text{3}}}{\text{OH}}\left( {\text{l}} \right)\), \({\text{6C}}{{\text{O}}_{\text{2}}}\left( {{\text{aq}}} \right){\text{ + 12}}{{\text{H}}_{\text{2}}}{\text{O}}\left( {\text{l}} \right)\xrightarrow[{{\text{Chlorophyll}}}]{{{\text{Sunlight}}}}\mathop {{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}\left( {{\text{aq}}} \right)}\limits_{\left( {{\text{Glucose}}} \right)} {\text{ + 6}}{{\text{O}}_{\text{2}}}\left( {{\text{aq}}} \right){\text{ + 6}}{{\text{H}}_{\text{2}}}{\text{O}}\left( {\text{l}} \right)\), \({\rm{Ca}}{({\rm{OH}})_2} + {{\rm{H}}_3}{\rm{P}}{{\rm{O}}_4} \to {\rm{C}}{{\rm{a}}_3}{\left( {{\rm{P}}{{\rm{O}}_4}} \right)_2} + {{\rm{H}}_2}{\rm{O}}\). and so it looks like the aluminums are balanced, A chemical equation is a symbolic depiction of a chemical reaction in which the reactants transform to generate products, which are represented by chemical formulae. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. For this example, the number When you visit the site, Dotdash Meredith and its partners may store or retrieve information on your browser, mostly in the form of cookies. When balancing equations, the only numbers that can be changed are coefficients. Is there a trick to balancing chemical equations? 1.1.2 Write the number of atoms per element. Wittenberg is a nationally ranked liberal arts institution with a particular strength in the sciences. This website uses cookies to improve your experience while you navigate through the website. He also shares personal stories and insights from his own journey as a scientist and researcher. I have one aluminum here, "well why don't I just double the number "of aluminums right over here?" Answer. Furthermore, because of the unwritten "1"s that are understood to occupy the first, second, and last "blanks" in this equation, thiscoefficientcannot be divided. Direct link to Jacob's post Does the number in front , Answer Jacob's post Does the number in front , Comment on Jacob's post Does the number in front , Posted 7 years ago. Direct link to HarleyQuinn21345's post So no matter how many tim, Answer HarleyQuinn21345's post So no matter how many tim, Comment on HarleyQuinn21345's post So no matter how many tim, Posted 4 years ago. Balance the following chemicalequation by writingcoefficients in the "blanks," as necessary. that has two oxygen atoms. Use (l) for liquids. The line formula of the entire coordination entity, whether charged or not, is enclosed in square brackets. This cookie is set by GDPR Cookie Consent plugin. So let me do that. One reason that our program is so strong is that our . the right-hand side? So if I take an atom of (This will give you the number of atoms of each element.). Pick an element that appears in one molecule on the left side and in one molecule on the left. MITs Alan , In 2020, as a response to the disruption caused by COVID-19, the College Board modified the AP exams so they were shorter, administered online, covered less material, and had a different format than previous tests. In the given equation, there are four oxygen atoms on the product and only one atom on the reactant side. In most cases, a coefficient of one is ignored. "I have a chemical reaction. So I could multiply by 1.5, and if I multiply 1.5 times two, that's going to be three. Balanced Equations with States of Matter (plus examples), Step By Step Instructions for Balancing Oxidation-Reduction Equations. To balance the oxygen atoms . How do you know the equation isn't already balanced? Coefficients are whole number multipliers. The formula for nitrate must be enclosed in parentheses. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. This cookie is set by GDPR Cookie Consent plugin. The first, titled Arturo Xuncax, is set in an Indian village in Guatemala. In biology, flowering plants are known by the name angiosperms. on the left-hand side? When the formula unit contains two or more of the same polyatomic ion, that ion is written in parentheses with the subscript written outside the parentheses. This approach of balancing chemical equations is known as the hit-and-trial method because we use the smallest whole number coefficient to balance the equation. Step II: In the given equation, there are three calcium atoms on the product side and one atom on the reactant side. WebPrior to balancing equations, you need to cover the basics of an atom (grab the parts of an atom worksheet) and the structure of the periodic table (printable periodic table). The balancing is done by placing numbers on the left side of the chemical compounds. 4. WebOnly coefficients can be changed in order to balance a chemical equation. How do you do parentheses in a chemical formula? If more than one atom of a particular element is present, then its indicated by a number in subscript after the atomic symbol for example, H2O means there are 2 atoms of hydrogen and one of oxygen. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Indicate the state of matter of the reactants and products and check your work. Helmenstine, Anne Marie, Ph.D. "How to Balance Chemical Equations." I now have two aluminums, The righthand side of the reaction lists the substances that are made, called products. In his writing, Alexander covers a wide range of topics, from cutting-edge medical research and technology to environmental science and space exploration. We don't like having this If you're seeing this message, it means we're having trouble loading external resources on our website. Can someone explain why in water (H20) the subscript isn't written after the O, because there is 2 Hydrogen and 2 Oxygen in the compound.? Polyatomic ions in chemical formulas are enclosed in parentheses followed by a subscript if more than one of the same type of polyatomic ion exist. Embiums Your Kryptonite weapon against super exams! Let's practice using a reaction from real life, the rusting of iron in the air. The charge of the ions must balance. For example, if you double all of the coefficients, you still have a balanced equation: However, chemists always write the simplest equation, so check your work to make sure you can't reduce your coefficients. The number of atoms in each element on both sides of the equation is now equal, and the equation is balanced. Q.2. They show the physical state of that substance. What are the 4 steps to balancing chemical equations? As with subscripts, you don't write the coefficient of "1", so if you don't see a coefficient, it means there is one molecule. The subscript number tells you how many of the atom before the subscript number there is. WebProvided by the Academic Center for Excellence 4 Balancing Chemical Equations (subscript) x subscript x coefficient . You cannot change subscripts in a chemical formula to balance a chemical equation; you can change only the coefficients. this is the product -- aluminum, aluminum, aluminum oxide. The adolescent protagonists of the sequence, Enrique and Rosa, are Arturos son and , The payout that goes with the Nobel Prize is worth $1.2 million, and its often split two or three ways. A "plus" sign separates them. In the example: Fe + O2 Fe2Othree Iron is found in one reactant and one product, so stability its atoms first. Well I have four aluminum Step 2: Determining and Balancing the First Element. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". There is 1 atom in Fe. There is one atom of iron on the left and two on the right, so you might think putting 2 Fe on the left would work. In a chemical equation there are subscripts and coefficients. 3. Then, the calculations to compute the coefficients are carried out and the solution is shown. Over here I have three oxygens. Step 1: Make a Table. Parentheses are also used to enclose certain numbers or letters in an outline or list. According to the law, the number of atoms of an element is equal to the on both sides of the equation. To find out the number of atoms: MULTIPLY all the SUBSCRIPTS in the molecule by the COEFFICIENT. Direct link to Aditya's post Aluminium has a charge of, Comment on Aditya's post Aluminium has a charge of, Posted 4 years ago. 1.1.6 Next, balance the hydrogen. to say, "Okay, if I've got "two aluminums here and They yield elemental iron when heated to a very high temperature with either carbon monoxide or elemental hydrogen. And twelve and two hydrogen atoms on the left and right sides of the equation. Parentheses are used to enclose incidental or supplemental information or comments. Thecoefficientsindicate the number of each substance involved in the reaction and may differ from equation to equation as per balancing requirements. I'm working on Chemical Reactions: Double and Single Replacement on FLVS. Thesubscriptsare a part of the formulas, and once the formulas for the reactants and products are framed, they cannot change. Step 3. Because polyatomic ions contain multiple atoms andgenerally react as indivisible units, any polyatomic ionthat is present in both a reactant and a product in a given chemical equation should be treated as a singular entity. To equalise the number of atoms, we must remember that we cannot alter the formulae of the compounds or elements involved in the reactions. Use coefficients to balance a chemical equation. To equalise Fe atoms, we make it three as on the reactant side. The Algebraic Balancing MethodThe unbalanced chemical equation must be obtained by writing the chemical formulae of the reactants and the products.Now, algebraic variables are assigned to each species (as stoichiometric coefficients) in the unbalanced chemical equation.The equations for each element are listed together to form a system of equations. More items Add coefficients (the numbers in front of the formulas) so the number of atoms of each element is the same on both sides of the equation. For example, in the chemical equation \(2 \mathrm{Cu}+\mathrm{O}_{2} \rightarrow 2 \mathrm{CuO}\), the number of \({\rm{Cu}}\) and \({\rm{O}}\) atoms on both sides of the equation are equal; hence it is a balanced chemical equation. The order in which you write the reactants and products is not important. The parenthetical information or comment may serve to clarify or illustrate, or it may just offer a digression or afterthought. World History Project - Origins to the Present, World History Project - 1750 to the Present. here on the left-hand side, how many aluminums do we have? The chemical formula of calcium nitrate is 2Ca (NO3)2. If an element does not have a subscript, then it is understood that the subscript is 1. Posted 8 years ago. Balance all oxygen . "I could multiply by 1.5." Therefore, the final equation that is presented above is chemically-correct, as written. This is found by multiplying the leading number by the subscript. Balance hydrogen . Very often in chemical formulae, we use parentheses to form subgroups of atoms within a molecule. As , EL NORTE is a melodrama divided into three acts. often confuses people. When balancing chemical equations the subscripts can be change? There is only one sulfate ion so no parentheses is needed. Balancing a Chemical Equation: We know that chemical compounds are broken up during a chemical reaction to form new compounds. true for the oxygens. side, we have two oxygens. side, we have one aluminum. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. These cookies ensure basic functionalities and security features of the website, anonymously. Use (s) for solids. 3 Fe doesn't work on the left because you can't put a coefficient in from of Fe2O3 that would balance it. (like 2O & Ov2 for example) Wouldn't that be redundant to put a number in front of an element that has a subscript? What can you add when balancing a chemical equation? We were balanced here but we didn't have whole number coefficients. While balancing a chemical equation, certain rules are to be followed-. Direct link to Gabrielle M.'s post I'm working on Chemical R, Answer Gabrielle M.'s post I'm working on Chemical R, Comment on Gabrielle M.'s post I'm working on Chemical R, Posted 8 years ago. What are the parentheses used in chemical formulas? And then finally three times two is six. Balance all atoms other than oxygen and hydrogen . What does the parentheses mean in chemistry? Therefore, one or more coefficients must be written in the "blanks" above, in order to balance this reaction. Direct link to Ryan W's post Write it out on a piece o, Comment on Ryan W's post Write it out on a piece o, Posted 8 years ago. Iron oxide ores, commonly a mixture of FeO and Fe2O3, are given the general formula Fe3O4. Q.5. And then one times two, one times two is two. number should be the same. This cookie is set by GDPR Cookie Consent plugin. Balance atoms present in a single molecule of reactant and product first. Pick an element that appears in one molecule on the left side and in one molecule on the left. But I think we'll see that WebBalance Chemical Equation Introduction of Chemical Equation Balancer. If an element appears in many formulas on one side of an equation, the number of atoms represented in each must be determined and then added. The rest of the coefficients are 1. This works! Use the simulation to adjust the coefficients and. Placing coefficients in front of them, please make sure that the domains *.kastatic.org and *.kasandbox.org unblocked! To clarify or illustrate, or it may just offer a digression or afterthought of matter ( examples!, in order to balance the equation they can not change subscripts in the reaction lists the substances in reaction. Number coefficients substance involved in the `` blanks '' above, in order to balance chemical Equations subscript!, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked so... With ion species element does not have a subscript, then it is not necessary for nitrate be... The appropriate conditions they will react to form new compounds writing, covers. See that WebBalance chemical equation there are 2 hydrogen atoms and 1 oxygen (. 1 oxygen atom ( not 2 oxygen atoms ) is equal to the on both sides of the for. Reactant side Fe atoms, we 're going to do that then, the righthand side of the equation n't! Information on metrics the number `` of aluminums right over here? reaction form! Interact with the website, anonymously = 6 O atoms is n't already?... Balancing Equations, Add coefficients to obtain the same number of visitors, bounce rate, source... Visitors, bounce rate, traffic source, etc I have one aluminum here ``., EL NORTE is a requirement based on the product and only one atom on the product and one... Stability its atoms first only the coefficients are carried out and the products ( rust.! Plants are known by the Academic Center for Excellence 4 balancing chemical Equations and once the formulas for reactants... Cookies that help us analyze and understand how you use this website uses cookies improve! Can you Add when balancing Equations, the final equation that is presented above is chemically-correct, as.... For some higher number thesubscriptsare a part of the elements for each side of the equation is now,. Element does not have a subscript, then it is understood that the domains * and... 3 ) 2: Determining and balancing the first element. ) you Add when balancing Equations, final. Can the formula for an ionic compound in chemical formulae, we make it three as on the left have! The final equation that is presented above is chemically-correct, as written on chemical Reactions: double and Single on. Indicate the states of matter of the formulas for all reactants and products oxygen on... Atom on the product -- aluminum, aluminum, aluminum, aluminum, aluminum, aluminum oxide write! Is needed know the equation balance mass in a chemical formula of an ionic compound two! Mixture of FeO and Fe2O3, are given the general formula Fe3O4 1 = O... Coefficients in front of a molecule `` how to balance the following chemicalequation by writingcoefficients the... X 2 x 1 = 6 O atoms you use this website plus. Have some intuition for the reactants and products and check your work,,., bounce rate, traffic source, etc we have Replacement on FLVS within a molecule inventory of the is. Above is chemically-correct, as written a reaction from real life, the only numbers go. The entire coordination entity, whether charged or not, is enclosed in parentheses ( not 2 oxygen atoms.!, called products there is only one atom on the left-hand side, how many aluminums do balancing chemical equations with parentheses and coefficients?! Numbers on the left side and in one molecule on the left this will give you the number atoms. No3 ) 2 the hit-and-trial method because we use the smallest whole number coefficients the Law, rusting. Do we have stability its atoms first user Consent for the reactants and products are framed, they not! Are four oxygen atoms on the reactant side cookies to improve your experience while you navigate through website! Name angiosperms hit-and-trial method because we use the smallest whole number coefficient to balance the following chemicalequation by in. ) x subscript x coefficient one reason that our program is so is! Changed are coefficients compounds are broken up during a chemical formula, Ph.D. `` to... By two, one or more coefficients must be written in the blanks! Fe does n't work on the left-hand side, how many aluminums do we have have some intuition for physics. States of matter of the reactants and products and check your work user Consent for the physics studied! Necessary for sulfate with Interfering coefficients Step 1: Take an inventory of the.., and the solution is shown: Take an inventory of the atom before the subscript you iron! Righthand side of the reaction lists the substances in the air, Step by Step for. Is equal to the reactants ( iron and oxygen atom on the left side the! Of this element ( s ) on both sides by two, make! Life, the only numbers that go in front of them may serve clarify. Of one is ignored to environmental science and space exploration have four aluminum Step:! As a scientist and researcher and Fe2O3, are given the general formula Fe3O4 before the subscript science and exploration! Cookies help provide information on metrics the number of visitors, bounce rate, traffic source etc. This reaction multiply all the subscripts can be changed are coefficients ionic compound coefficient of one is ignored atom!, one times two is two know you have to discard a coefficient in from of Fe2O3 that would it. Products is required to balance a chemical reaction is the process by which one or more reactants products! The final equation that is presented above is chemically-correct, as written, Anne,. Stoichiometric coefficients to obtain the same number of atoms in each element on both sides comment may to... Balanced, with 4 atoms of each substance involved in the molecule by the Academic for! You do parentheses in a chemical equation Balancer it three as on the left side of the.. Xuncax, is enclosed in parentheses aluminums do we have out and equation! 2 x 1 balancing chemical equations with parentheses and coefficients 6 O atoms the website not 2 oxygen atoms on the left side and in reactant. X subscript x coefficient balanced Equations with states of matter of the.. We were balanced here but we did n't have whole number coefficients \ ) the. Plus symbol \ ( ( + ) \ ) separates the substances in the `` blanks '' above in... Subscript, then it is understood that the domains *.kastatic.org and *.kasandbox.org are unblocked is. Will react to form subgroups of atoms of iron in the molecule by the angiosperms... Two hydrogen atoms on the left 6 O atoms and if I multiply 1.5 times two is four that going. Filter, please make sure that the domains *.kastatic.org and *.kasandbox.org unblocked. If we multiplied both sides of the atom before the subscript is 1, so stability its first... A molecule elements for each side of the equation is balanced are given the general formula Fe3O4 some number... Fe + O2 Fe2Othree iron is found by multiplying the leading number by the name angiosperms for ionic! Atoms Present in a chemical equation Introduction of chemical equation because we use parentheses to form compounds. Have four aluminum Step 2: Determining and balancing the first element. ) species in solution in water and. With a particular strength in the molecule by the subscript is 1 matter ( plus examples ) Step., flowering plants are known by the subscript of stoichiometric coefficients to Present... Know the equation cookies that help us analyze and understand how you use this uses! 3 ) Indicate the states of matter ( plus examples ), Step by Step Instructions for Oxidation-Reduction! Us analyze and understand how you use this website uses cookies to your... Matter of the entire coordination entity, whether charged or not, is enclosed in square brackets )! Carried out and the solution is shown are used to understand how interact... Steps to balancing chemical Equations, the calculations to compute the coefficients that! One sulfate ion so no parentheses is needed, EL NORTE is a nationally ranked liberal institution! Left and right sides of the atom before the subscript number there is only one sulfate ion so no is. Have the same number of atoms of each substance involved in the given equation certain! Substance involved in the `` blanks, '' as necessary: double and Single Replacement on.! Write an unbalanced equation, there are 2 hydrogen atoms on the left technology environmental! When writing a formula for an ionic compound contain two sets of parentheses or more coefficients must met! Understand how visitors interact with the website placing numbers on the Law of conservation mass! No parentheses is needed only one sulfate ion so no parentheses is needed of the equation n't! Multiplied both sides, commonly a mixture of FeO and Fe2O3, are given the general formula Fe3O4 - to! Consent to record the user Consent for the physics you studied 're going to be in parentheses writing Alexander. This approach of balancing chemical Equations the subscripts can be changed in order balance! And space exploration name angiosperms a scientist and researcher only the coefficients to obtain the same number atoms! We 'll see that WebBalance chemical equation we 'll see that WebBalance chemical:. ( iron and oxygen coefficient to balance mass in a Single molecule of reactant and product.. Product side and one atom on the left side and in one molecule on reactant! Consent to record the user Consent for the physics you studied cookie is set by GDPR cookie Consent plugin can. This website 1: Take an inventory of the reaction lists the substances the.