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what does it mean to balance an equation

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Learning Objectives

By the end of this department, yous will exist able to:

  • Derive chemic equations from narrative descriptions of chemical reactions.
  • Write and balance chemical equations in molecular, full ionic, and net ionic formats.

The preceding chapter introduced the use of element symbols to represent individual atoms. When atoms proceeds or lose electrons to yield ions, or combine with other atoms to form molecules, their symbols are modified or combined to generate chemical formulas that appropriately correspond these species. Extending this symbolism to represent both the identities and the relative quantities of substances undergoing a chemic (or physical) modify involves writing and balancing a chemic equation. Consider as an case the reaction betwixt one methane molecule (CH4) and two diatomic oxygen molecules (O2) to produce one carbon dioxide molecule (CO2) and ii water molecules (HtwoO). The chemical equation representing this process is provided in the upper half of Effigy ane, with space-filling molecular models shown in the lower half of the figure.

This figure shows a balanced chemical equation followed below by a representation of the equation using space-filling models. The equation reads C H subscript 4 plus 2 O subscript 2 arrow C O subscript 2 plus 2 H subscript 2 O. Under the C H subscript 4, the molecule is shown with a central black sphere, representing a C atom, to which 4 smaller white spheres, representing H atoms, are distributed evenly around. All four H atoms are bonded to the central black C atom. This is followed by a plus sign. Under the 2 O subscript 2, two molecules are shown. The molecules are each composed of two red spheres bonded together. The red spheres represent O atoms. To the right of an arrow and under the C O subscript 2, appears a single molecule with a black central sphere with two red spheres bonded to the left and right. Following a plus sign and under the 2 H subscript 2 O, are two molecules, each with a central red sphere and two smaller white spheres attached to the lower right and lower left sides of the central red sphere. Note that in space filling models of molecules, spheres appear slightly compressed in regions where there is a bond between two atoms.

Figure 1. The reaction betwixt methane and oxygen to yield carbon dioxide in water (shown at bottom) may be represented by a chemical equation using formulas (tiptop).

This example illustrates the fundamental aspects of whatsoever chemical equation:

  1. The substances undergoing reaction are chosen reactants, and their formulas are placed on the left side of the equation.
  2. The substances generated by the reaction are chosen products, and their formulas are placed on the right sight of the equation.
  3. Plus signs (+) separate individual reactant and production formulas, and an arrow ([latex]\rightarrow[/latex]) separates the reactant and product (left and right) sides of the equation.
  4. The relative numbers of reactant and production species are represented by coefficients (numbers placed immediately to the left of each formula). A coefficient of 1 is typically omitted.

Information technology is mutual practice to use the smallest possible whole-number coefficients in a chemical equation, as is done in this example. Realize, still, that these coefficients represent the relative numbers of reactants and products, and, therefore, they may be correctly interpreted as ratios. Marsh gas and oxygen react to yield carbon dioxide and water in a i:two:1:2 ratio. This ratio is satisfied if the numbers of these molecules are, respectively, 1-2-1-two, or 2-4-2-4, or 3-6-iii-6, and so on (Effigy two). Likewise, these coefficients may be interpreted with regard to any amount (number) unit, and and then this equation may be correctly read in many means, including:

  • One methane molecule and two oxygen molecules react to yield 1 carbon dioxide molecule and ii water molecules.
  • One dozen marsh gas molecules and two dozen oxygen molecules react to yield one dozen carbon dioxide molecules and 2 dozen water molecules.
  • One mole of methane molecules and 2 moles of oxygen molecules react to yield 1 mole of carbon dioxide molecules and 2 moles of h2o molecules.

This image has a left side, labeled,

Effigy ii. Regardless of the absolute number of molecules involved, the ratios between numbers of molecules are the same as that given in the chemical equation.

Balancing Equations

Acounterbalanced chemic is equationhas equal numbers of atoms for each element involved in the reaction are represented on the reactant and product sides. This is a requirement the equation must satisfy to exist consistent with the police of conservation of matter. Information technology may be confirmed by just summing the numbers of atoms on either side of the pointer and comparing these sums to ensure they are equal. Note that the number of atoms for a given element is calculated by multiplying the coefficient of whatsoever formula containing that element by the chemical element'southward subscript in the formula. If an element appears in more 1 formula on a given side of the equation, the number of atoms represented in each must be computed and so added together. For example, both product species in the instance reaction, CO2 and HiiO, incorporate the chemical element oxygen, and so the number of oxygen atoms on the production side of the equation is

[latex]\left(1{\text{CO}}_{2}\text{ molecule }\times \frac{\text{2 O atoms}}{{\text{CO}}_{2}\text{ molecule }}\right)+\left(2{\text{H}}_{2}\text{O molecule }\times \frac{\text{1 O cantlet}}{{\text{H}}_{2}\text{O molecule }}\right)=\text{four O atoms}[/latex]

The equation for the reaction between methane and oxygen to yield carbon dioxide and h2o is confirmed to be balanced per this approach, as shown hither:

[latex]{\text{CH}}_{iv}+two{\text{O}}_{ii}\rightarrow{\text{CO}}_{2}+ii{\text{H}}_{2}\text{O}[/latex]

Element Reactants Products Balanced?
C 1 × 1 = 1 1 × ane = i 1 = one, yes
H 4 × 1 = 4 2 × 2 = 4 four = 4, yes
O two × ii = 4 (one × 2) + (2 × ane) = 4 iv = four, yeah

A balanced chemical equation oftentimes may be derived from a qualitative description of some chemical reaction by a fairly simple arroyo known every bit balancing by inspection. Consider equally an example the decomposition of water to yield molecular hydrogen and oxygen. This process is represented qualitatively by an unbalanced chemical equation:

[latex]{\text{H}}_{2}\text{O}\rightarrow{\text{H}}_{2}+{\text{O}}_{2}\text{(unbalanced)}[/latex]

Comparison the number of H and O atoms on either side of this equation confirms its imbalance:

Element Reactants Products Balanced?
H 1 × 2 = 2 1 × 2 = two 2 = 2, yeah
O 1 × 1 = 1 1 × ii = two 1 ≠ 2, no

The numbers of H atoms on the reactant and production sides of the equation are equal, but the numbers of O atoms are non. To achieve rest, the coefficients of the equation may be changed every bit needed. Go on in mind, of course, that the formula subscripts define, in part, the identity of the substance, and then these cannot exist changed without altering the qualitative meaning of the equation. For instance, changing the reactant formula from H2O to H2O2 would yield rest in the number of atoms, but doing so also changes the reactant's identity (it's now hydrogen peroxide and non water). The O atom balance may be achieved by irresolute the coefficient for H2O to 2.

[latex]\mathbf{2}\text{H}_{2}\text{O}\rightarrow{\text{H}}_{2}+{\text{O}}_{2}\text{(unbalanced)}[/latex]

Element Reactants Products Balanced?
H ii × 2 = 4 1 × 2 = 2 four ≠ 2, no
O 2 × 1 = 2 1 × 2 = 2 2 = 2, yep

The H cantlet balance was upset by this modify, just it is hands reestablished past changing the coefficient for the H2 product to 2.

[latex]2{\text{H}}_{ii}\text{O}\rightarrow\mathbf{two}{\text{H}}_{2}+{\text{O}}_{2}\text{(balanced)}[/latex]

Element Reactants Products Counterbalanced?
H 2 × 2 = 4 2 × 2 = 2 four = 4, yes
O 2 × 1 = 2 1 × 2 = 2 2 = 2, yeah

These coefficients yield equal numbers of both H and O atoms on the reactant and production sides, and the balanced equation is, therefore:

[latex]2{\text{H}}_{ii}\text{O}\rightarrow two{\text{H}}_{two}+{\text{O}}_{two}[/latex]

Example 1:Balancing Chemical Equations

Write a balanced equation for the reaction of molecular nitrogen (North2) and oxygen (O2) to form dinitrogen pentoxide.

Bank check Your Learning

Write a balanced equation for the decomposition of ammonium nitrate to grade molecular nitrogen, molecular oxygen, and water. (Hint: Balance oxygen last, since it is present in more than one molecule on the right side of the equation.)

[latex]2{\text{NH}}_{4}{\text{NO}}_{3}\rightarrow 2{\text{N}}_{2}+{\text{O}}_{2}+4{\text{H}}_{2}\text{O}[/latex]

It is sometimes convenient to use fractions instead of integers as intermediate coefficients in the process of balancing a chemical equation. When remainder is achieved, all the equation's coefficients may then be multiplied past a whole number to catechumen the fractional coefficients to integers without upsetting the atom balance. For example, consider the reaction of ethane (C2Hhalf-dozen) with oxygen to yield H2O and CO2, represented past the unbalanced equation:

[latex]{\text{C}}_{two}{\text{H}}_{half-dozen}+{\text{O}}_{2}\rightarrow{\text{H}}_{ii}\text{O}+{\text{CO}}_{two}\text{(unbalanced)}[/latex]

Post-obit the usual inspection approach, ane might first residue C and H atoms past changing the coefficients for the two production species, as shown:

[latex]{\text{C}}_{2}{\text{H}}_{vi}+{\text{O}}_{two}\rightarrow iii{\text{H}}_{2}\text{O}+2{\text{CO}}_{2}\text{(unbalanced)}[/latex]

This results in seven O atoms on the product side of the equation, an odd number—no integer coefficient can be used with the Otwo reactant to yield an odd number, so a fractional coefficient, [latex]\displaystyle\frac{7}{2}[/latex] , is used instead to yield a provisional balanced equation:

[latex]{\text{C}}_{2}{\text{H}}_{6}+\frac{vii}{2}{\text{O}}_{2}\rightarrow 3{\text{H}}_{two}\text{O}+2{\text{CO}}_{2}[/latex]

A conventional counterbalanced equation with integer-but coefficients is derived past multiplying each coefficient by 2:

[latex]2{\text{C}}_{two}{\text{H}}_{6}+7{\text{O}}_{2}\rightarrow 6{\text{H}}_{two}\text{O}+4{\text{CO}}_{ii}[/latex]

Finally with regard to balanced equations, think that convention dictates utilise of the smallest whole-number coefficients. Although the equation for the reaction between molecular nitrogen and molecular hydrogen to produce ammonia is, indeed, balanced,

[latex]3{\text{N}}_{two}+9{\text{H}}_{ii}\rightarrow half-dozen{\text{NH}}_{3}[/latex]

the coefficients are non the smallest possible integers representing the relative numbers of reactant and product molecules. Dividing each coefficient by the greatest common cistron, 3, gives the preferred equation:

[latex]{\text{Northward}}_{2}+3{\text{H}}_{2}\rightarrow ii{\text{NH}}_{iii}[/latex]

Exercises

Remainder the post-obit equations:

  1. [latex]{\text{PCl}}_{5}\text{(}s\text{)}+{\text{H}}_{2}\text{O(}l\text{)}\rightarrow{\text{POCl}}_{3}\text{(}l\text{)}+\text{HCl(}aq\text{)}[/latex]
  2. [latex]\text{Ag}\text{(}south\text{)}+{\text{H}}_{2}\text{S}\text{(}g\text{)}+{\text{O}}_{2}\text{(}chiliad\text{)}\rightarrow{\text{Ag}}_{2}\text{S}\text{(}s\text{)}+{\text{H}}_{2}\text{O}\text{(}l\text{)}[/latex]
  3. [latex]\text{Cu(}south\text{)}+{\text{HNO}}_{3}\text{(}aq\text{)}\rightarrow\text{Cu}{\text{(}{\text{NO}}_{3}\text{)}}_{2}\text{(}aq\text{)}+{\text{H}}_{2}\text{O(}50\text{)}+\text{NO(}g\text{)}[/latex]
  4. [latex]{\text{P}}_{iv}\text{(}s\text{)}+{\text{O}}_{2}\text{(}g\text{)}\rightarrow{\text{P}}_{4}{\text{O}}_{10}\text{(}s\text{)}[/latex]
  5. [latex]{\text{H}}_{2}\text{(}g\text{)}+{\text{I}}_{2}\text{(}south\text{)}\rightarrow\text{Hello(}s\text{)}[/latex]
  6. [latex]\text{Lead(}southward\text{)}+{\text{H}}_{2}\text{O(}50\text{)}+{\text{O}}_{2}\text{(}1000\text{)}\rightarrow{\text{Pb(OH)}}_{2}\text{(}due south\text{)}[/latex]
  7. [latex]\text{Atomic number 26(}southward\text{)}+{\text{O}}_{2}\text{(}g\text{)}\rightarrow{\text{Atomic number 26}}_{two}{\text{O}}_{three}\text{(}s\text{)}[/latex]
  8. [latex]\text{Fe(}s\text{)}+{\text{H}}_{2}\text{O(}fifty\text{)}\rightarrow{\text{Fe}}_{3}{\text{O}}_{4}\text{(}s\text{)}+{\text{H}}_{2}\text{(}g\text{)}[/latex]
  9. [latex]\text{Na(}south\text{)}+{\text{H}}_{2}\text{O(}l\text{)}\rightarrow\text{NaOH}\text{(}aq\text{)}+{\text{H}}_{2}\text{(}one thousand\text{)}[/latex]
  10. [latex]{\text{Sc}}_{ii}{\text{O}}_{iii}\text{(}southward\text{)}+{\text{Then}}_{3}\text{(}fifty\text{)}\rightarrow{\text{Sc}}_{two}{\text{(}{\text{And then}}_{4}\text{)}}_{three}\text{(}s\text{)}[/latex]
  11. [latex]{\text{(}{\text{NH}}_{iv}\text{)}}_{ii}{\text{Cr}}_{2}{\text{O}}_{7}\text{(}s\text{)}\rightarrow{\text{Cr}}_{2}{\text{O}}_{3}\text{(}s\text{)}+{\text{N}}_{2}\text{(}thou\text{)}+{\text{H}}_{2}\text{O(}thou\text{)}[/latex]
  12. [latex]{\text{Ca}}_{three}{\text{(}{\text{PO}}_{4}\text{)}}_{two}\text{(}aq\text{)}+{\text{H}}_{iii}{\text{PO}}_{iv}\text{(}aq\text{)}\rightarrow\text{Ca}{\text{(}{\text{H}}_{2}{\text{PO}}_{four}\text{)}}_{2}\text{(}aq\text{)}[/latex]
  13. [latex]{\text{P}}_{4}\text{(}due south\text{)}+{\text{Cl}}_{2}\text{(}g\text{)}\rightarrow{\text{PCl}}_{3}\text{(}l\text{)}[/latex]
  14. [latex]\text{Al(}south\text{)}+{\text{H}}_{2}{\text{SO}}_{four}\text{(}aq\text{)}\rightarrow{\text{Al}}_{2}{\text{(}{\text{SO}}_{4}\text{)}}_{3}\text{(}aq\text{)}+{\text{H}}_{2}\text{(}grand\text{)}[/latex]
  15. [latex]{\text{PtCl}}_{4}\text{(}south\text{)}\rightarrow\text{Pt}\text{(}southward\text{)}+{\text{Cl}}_{2}\text{(}m\text{)}[/latex]
  16. [latex]{\text{TiCl}}_{iv}\text{(}due south\text{)}+{\text{H}}_{2}\text{O(}1000\text{)}\rightarrow{\text{TiO}}_{two}\text{(}south\text{)}+\text{HCl(}one thousand\text{)}[/latex]

Boosted Information in Chemic Equations

The physical states of reactants and products in chemical equations very often are indicated with a parenthetical abridgement following the formulas. Common abbreviations include south for solids, l for liquids, thou for gases, and aq for substances dissolved in water (aqueous solutions, as introduced in the preceding chapter). These notations are illustrated in the case equation hither:

[latex]2\text{Na(}s\text{)}+2{\text{H}}_{2}\text{O(}l\text{)}\rightarrow 2\text{NaOH(}aq\text{)}+{\text{H}}_{ii}\text{(}g\text{)}[/latex]

This equation represents the reaction that takes place when sodium metal is placed in h2o. The solid sodium reacts with liquid water to produce molecular hydrogen gas and the ionic compound sodium hydroxide (a solid in pure course, simply readily dissolved in water).

Special conditions necessary for a reaction are sometimes designated by writing a word or symbol in a higher place or below the equation's arrow. For example, a reaction carried out by heating may be indicated past the uppercase Greek letter of the alphabet delta (Δ) over the pointer.

[latex]{\text{CaCO}}_{3}\text{(}s\text{)}\stackrel{\Delta}{\rightarrow}\text{CaO(}south\text{)}+{\text{CO}}_{2}\text{(}g\text{)}[/latex]

Other examples of these special conditions volition be encountered in more depth in afterwards capacity.

Equations for Ionic Reactions

Given the abundance of water on world, it stands to reason that a great many chemic reactions accept place in aqueous media. When ions are involved in these reactions, the chemical equations may be written with diverse levels of item appropriate to their intended employ. To illustrate this, consider a reaction between ionic compounds taking place in an aqueous solution. When aqueous solutions of CaCltwo and AgNO3 are mixed, a reaction takes identify producing aqueous Ca(NO3)ii and solid AgCl:

[latex]{\text{CaCl}}_{ii}\text{(}aq\text{)}+2{\text{AgNO}}_{3}\text{(}aq\text{)}\rightarrow\text{Ca}{\text{(}{\text{NO}}_{iii}\text{)}}_{2}\text{(}aq\text{)}+2\text{AgCl(}s\text{)}[/latex]

This balanced equation, derived in the usual style, is called a molecular equation, because information technology doesn't explicitly correspond the ionic species that are present in solution. When ionic compounds deliquesce in water, they may dissociate into their constituent ions, which are afterwards dispersed homogenously throughout the resulting solution (a thorough discussion of this important procedure is provided in the chapter on solutions). Ionic compounds dissolved in h2o are, therefore, more realistically represented as dissociated ions, in this instance:

[latex]\brainstorm{array}{l}{\text{CaCl}}_{two}\text{(}aq\text{)}\rightarrow{\text{Ca}}^{\text{2+}}\text{(}aq\text{)}+two{\text{Cl}}^{-}\text{(}aq\text{)}\\ 2{\text{AgNO}}_{3}\text{(}aq\text{)}\rightarrow ii{\text{Ag}}^{\text{+}}\text{(}aq\text{)}+two{\text{NO}}_{3}{}^{-}\text{(}aq\text{)}\\ \text{Ca}{\text{(}{\text{NO}}_{iii}\text{)}}_{two}\text{(}aq\text{)}\rightarrow{\text{Ca}}^{\text{2+}}\text{(}aq\text{)}+2{\text{NO}}_{iii}{}^{-}\text{(}aq\text{)}\end{array}[/latex]

Unlike these three ionic compounds, AgCl does non dissolve in water to a pregnant extent, as signified by its concrete state annotation, due south.

Explicitly representing all dissolved ions results in a consummate ionic equation. In this particular case, the formulas for the dissolved ionic compounds are replaced by formulas for their dissociated ions:

[latex]{\text{Ca}}^{\text{two+}}\text{(}aq\text{)}+two{\text{Cl}}^{-}\text{(}aq\text{)}+two{\text{Ag}}^{\text{+}}\text{(}aq\text{)}+two{\text{NO}}_{3}{}^{-}\text{(}aq\text{)}\rightarrow{\text{Ca}}^{\text{two+}}\text{(}aq\text{)}+2{\text{NO}}_{3}{}^{-}\text{(}aq\text{)}+2\text{AgCl(}s\text{)}[/latex]

Examining this equation shows that ii chemical species are present in identical form on both sides of the arrow, Ca2+(aq) and [latex]{\text{NO}}_{3}{}^{-}\text{(}aq\text{)}[/latex]. These spectator ions—ions whose presence is required to maintain charge neutrality—are neither chemically nor physically changed past the process, and so they may exist eliminated from the equation to yield a more succinct representation called a net ionic equation:

[latex]\brainstorm{assortment}{c}\cancel{{\text{Ca}}^{\text{two+}}\text{(}aq\text{)}}+2{\text{Cl}}^{-}\text{(}aq\text{)}+2{\text{Ag}}^{\text{+}}\text{(}aq\text{)}+\abolish{2{\text{NO}}_{3}{}^{\text{-}}\text{(}aq\text{)}}\rightarrow\cancel{{\text{Ca}}^{\text{two+}}\text{(}aq\text{)}}+\cancel{2{\text{NO}}_{3}{}^{-}\text{(}aq\text{)}}+ii\text{AgCl(}s\text{)}\\ 2{\text{Cl}}^{-}\text{(}aq\text{)}+2{\text{Ag}}^{\text{+}}\text{(}aq\text{)}\rightarrow 2\text{AgCl(}s\text{)}\cease{array}[/latex]

Following the convention of using the smallest possible integers every bit coefficients, this equation is and then written:

[latex]{\text{Cl}}^{\text{-}}\text{(}aq\text{)}+{\text{Ag}}^{+}\text{(}aq\text{)}\rightarrow\text{AgCl(}due south\text{)}[/latex]

This cyberspace ionic equation indicates that solid silver chloride may be produced from dissolved chloride and silver(I) ions, regardless of the source of these ions. These molecular and complete ionic equations provide additional information, namely, the ionic compounds used equally sources of Cl– and Ag+.

Example ii:Molecular and Ionic Equations

When carbon dioxide is dissolved in an aqueous solution of sodium hydroxide, the mixture reacts to yield aqueous sodium carbonate and liquid water. Write balanced molecular, complete ionic, and net ionic equations for this process.

Check Your Learning

Diatomic chlorine and sodium hydroxide (lye) are commodity chemicals produced in big quantities, forth with diatomic hydrogen, via the electrolysis of brine, according to the following unbalanced equation:

[latex]\text{NaCl(}aq\text{)}+{\text{H}}_{2}\text{O(}fifty\text{)}\,\,\,{\xrightarrow{\text{electricity}}}\,\,\,\text{NaOH(}aq\text{)}+{\text{H}}_{2}\text{(}thou\text{)}+{\text{Cl}}_{2}\text{(}g\text{)}[/latex]

Write counterbalanced molecular, consummate ionic, and net ionic equations for this process.

[latex]\brainstorm{array}{l}2\text{NaCl(}aq\text{)}+two{\text{H}}_{2}\text{O(}fifty\text{)}\rightarrow two\text{NaOH}\text{(}aq\text{)}+{\text{H}}_{2}\text{(}g\text{)}+{\text{Cl}}_{ii}\text{(}1000\text{)}\text{(}\text{molecular}\text{)}\\ 2{\text{Na}}^{\text{+}}\text{(}aq\text{)}+two{\text{Cl}}^{\text{-}}\text{(}aq\text{)}+2{\text{H}}_{2}\text{O(}l\text{)}\rightarrow 2{\text{Na}}^{\text{+}}\text{(}aq\text{)}+2{\text{OH}}^{\text{-}}\text{(}aq\text{)}+{\text{H}}_{ii}\text{(}g\text{)}+{\text{Cl}}_{2}\text{(}grand\text{)}\text{(}\text{complete ionic}\text{)}\\ two{\text{Cl}}^{\text{-}}\text{(}aq\text{)}+2{\text{H}}_{2}\text{O(}l\text{)}\rightarrow 2{\text{OH}}^{\text{-}}\text{(}aq\text{)}+{\text{H}}_{2}\text{(}k\text{)}+{\text{Cl}}_{2}\text{(}g\text{)}\text{(net ionic)}\end{assortment}[/latex]

Key Concepts and Summary

Chemic equations are symbolic representations of chemical and physical changes. Formulas for the substances undergoing the change (reactants) and substances generated by the modify (products) are separated by an arrow and preceded by integer coefficients indicating their relative numbers. Balanced equations are those whose coefficients result in equal numbers of atoms for each element in the reactants and products. Chemical reactions in aqueous solution that involve ionic reactants or products may be represented more realistically by complete ionic equations and, more succinctly, by internet ionic equations.

Exercises

  1. What does it hateful to say an equation is balanced? Why is information technology of import for an equation to be balanced?
  2. Consider molecular, complete ionic, and net ionic equations.
    1. What is the difference between these types of equations?
    2. In what circumstance would the complete and net ionic equations for a reaction exist identical?
  3. Write a balanced molecular equation describing each of the post-obit chemical reactions.
    1. Solid calcium carbonate is heated and decomposes to solid calcium oxide and carbon dioxide gas.
    2. Gaseous butane, C4H10, reacts with diatomic oxygen gas to yield gaseous carbon dioxide and water vapor.
    3. Aqueous solutions of magnesium chloride and sodium hydroxide react to produce solid magnesium hydroxide and aqueous sodium chloride.
    4. Water vapor reacts with sodium metal to produce solid sodium hydroxide and hydrogen gas.
  4. Write a balanced equation describing each of the following chemical reactions.
    1. Solid potassium chlorate, KClOiii, decomposes to grade solid potassium chloride and diatomic oxygen gas.
    2. Solid aluminum metal reacts with solid diatomic iodine to form solid Al2Ihalf-dozen.
    3. When solid sodium chloride is added to aqueous sulfuric acid, hydrogen chloride gas and aqueous sodium sulfate are produced.
    4. Aqueous solutions of phosphoric acid and potassium hydroxide react to produce aqueous potassium dihydrogen phosphate and liquid water.
  5. Colorful fireworks often involve the decomposition of barium nitrate and potassium chlorate and the reaction of the metals magnesium, aluminum, and iron with oxygen.
    1. Write the formulas of barium nitrate and potassium chlorate.
    2. The decomposition of solid potassium chlorate leads to the germination of solid potassium chloride and diatomic oxygen gas. Write an equation for the reaction.
    3. The decomposition of solid barium nitrate leads to the formation of solid barium oxide, diatomic nitrogen gas, and diatomic oxygen gas. Write an equation for the reaction.
    4. Write dissever equations for the reactions of the solid metals magnesium, aluminum, and iron with diatomic oxygen gas to yield the corresponding metal oxides. (Assume the iron oxide contains Fe+ ions.)
  6. Fill up in the blank with a single chemical formula for a covalent chemical compound that will balance the equation:This figure shows a chemical reaction. On the left side of the reaction arrow, a structural formula for a molecule is shown on the far left. It has a C atom on the left to which H atoms are bonded above, below, and to the left. To the right, another C atom is bonded which has H atoms bonded above and below. To the right, another C atom is bonded, which has a double bonded O atom above and another O atom singly bonded to the right. To the right of the singly bonded O atom, an H atom is bonded. This is followed by a plus sign and N a O H. A reaction arrow appears to the right, which is followed by another structural formula. It has a C atom on the left to which H atoms are bonded above, below, and to the left. To the right, another C atom is bonded which has H atoms bonded above and below. To the right, another C atom is bonded, which has a double bonded O atom above and another O atom singly bonded to the right. The singly bonded O atom is followed by a superscript negative sign. This is followed to the right by a plus sign, N a superscript positive sign, another plus sign, and a horizontal line segment, indicating a space for an answer to be written.
  7. Aqueous hydrogen fluoride (hydrofluoric acrid) is used to etch glass and to analyze minerals for their silicon content. Hydrogen fluoride will also react with sand (silicon dioxide).
    1. Write an equation for the reaction of solid silicon dioxide with hydrofluoric acid to yield gaseous silicon tetrafluoride and liquid h2o.
    2. The mineral fluorite (calcium fluoride) occurs extensively in Illinois. Solid calcium fluoride can also be prepared by the reaction of aqueous solutions of calcium chloride and sodium fluoride, yielding aqueous sodium chloride every bit the other product. Write complete and internet ionic equations for this reaction.
  8. A novel process for obtaining magnesium from sea water involves several reactions. Write a balanced chemical equation for each step of the process.
    1. The beginning stride is the decomposition of solid calcium carbonate from seashells to class solid calcium oxide and gaseous carbon dioxide.
    2. The second footstep is the formation of solid calcium hydroxide as the but production from the reaction of the solid calcium oxide with liquid water.
    3. Solid calcium hydroxide is and so added to the seawater, reacting with dissolved magnesium chloride to yield solid magnesium hydroxide and aqueous calcium chloride.
    4. The solid magnesium hydroxide is added to a hydrochloric acid solution, producing dissolved magnesium chloride and liquid water.
    5. Finally, the magnesium chloride is melted and electrolyzed to yield liquid magnesium metal and diatomic chlorine gas.
  9. From the balanced molecular equations, write the consummate ionic and net ionic equations for the following:
    1. [latex]{\text{K}}_{ii}{\text{C}}_{two}{\text{O}}_{4}\text{(}aq\text{)}+\text{Ba}{\text{(OH)}}_{ii}\text{(}aq\text{)}\rightarrow two\text{KOH(}aq\text{)}+{\text{BaC}}_{2}{\text{O}}_{2}\text{(}southward\text{)}[/latex]
    2. [latex]{\text{Atomic number 82(NO}}_{3}{\text{)}}_{ii}\text{(}aq\text{)}+{\text{H}}_{2}{\text{SO}}_{4}\text{(}aq\text{)}\rightarrow{\text{PbSO}}_{4}\text{(}south\text{)}+2{\text{HNO}}_{iii}\text{(}aq\text{)}[/latex]
    3. [latex]{\text{CaCO}}_{3}\text{(}south\text{)}+{\text{H}}_{2}{\text{And so}}_{4}\text{(}aq\text{)}\rightarrow{\text{CaSO}}_{4}\text{(}s\text{)}+{\text{CO}}_{2}\text{(}g\text{)}+{\text{H}}_{2}\text{O(}l\text{)}[/latex]

Glossary

balanced equation:chemical equation with equal numbers of atoms for each chemical element in the reactant and product

chemic equation:symbolic representation of a chemic reaction

coefficient:number placed in front of symbols or formulas in a chemical equation to indicate their relative corporeality

complete ionic equation:chemical equation in which all dissolved ionic reactants and products, including spectator ions, are explicitly represented past formulas for their dissociated ions

molecular equation:chemic equation in which all reactants and products are represented every bit neutral substances

internet ionic equation:chemic equation in which only those dissolved ionic reactants and products that undergo a chemical or physical change are represented (excludes spectator ions)

product:substance formed by a chemic or physical modify; shown on the right side of the pointer in a chemical equation

reactant:substance undergoing a chemical or concrete alter; shown on the left side of the arrow in a chemical equation

spectator ion: ion that does not undergo a chemical or concrete change during a reaction, but its presence is required to maintain charge neutrality

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Source: https://courses.lumenlearning.com/atd-sanjac-introductorychemistry/chapter/writing-and-balancing-chemical-equations-2/

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