Chemical Reactions and Writing Chemical Equations Lab Report

Experiment – Studying Chemical Reactions and Writing Chemical

Equations

Directions: To complete the experiment, watch each of the videos below, and use the data provided in the video to complete the experiment.

The experimental report must be submitted to the appropriate Blackboard assignment folder.

Reading Assignment:

Studying Chemical Reactions and Writing Chemical Equations

 

Experimental Videos

 

 

https://youtu.be/nP3HzDB19XE https://youtu.be/MMKnhQhtaXc https://youtu.be/WOU5YvaFqPk

 

 

 

For each reaction (there are 13 reactions in the video): (Neatness matters) Everything must be typed. All reactants and products must have their physical states indicated. (example H2O (l))

  1. Describe the appearance of each reactant.
  2. Provide any evidence that a chemical reaction occurred.
  3. Write the chemical equation.
  4. Write the complete ionic equation.
  5. Write the net ionic equation.
  6. Name the general reaction type.

 

 

 

 

 

 

 

 

A. Neidig

word image 1323

editor:

H.

Studying Chemical Reactions and Writing

Chemical Equations

prepared by M. L. Gillette, Indiana University/Kokomo and H. Anthony Neidig, Lebanon Valley College

 

PurpoSe of the Experiment

Describe chemical reactions by writing chemical equations based on laboratory.observations and information about reactions of different substances.

Background Information

word image 1324 word image 1325 word image 1326 word image 1327 word image 1328 The human digestive process depends on a high concentration of hydrochloric acid (HCI) in the stomach. Sometimes the HC} concentration becomes too high, which causes discomfort (“acid stomach’). When this condition occurs, many people take antac word image 1329 ids to help neutralize the excess acid. The active ingredient in many antacids is magnesium hydroxide, Mg(OH)2. When solid Mg(OH)2 mixes with HCI solution, a chemical reaction occurs. We can describe this reaction as: Mg(OH)2 reacts with HCI to produce magnesium chloride (MgC12) and water (H20).

We can make the same statement more concisely by writing a chemical equation for the reaction. A chemical equation, the symbolic description of a chemical process, shows the substances that react, the reactants, and the substances that form as a result of a chemical change, the products. An arrow indicates that the process occurs and is read ‘yields.” The chemical equation for the reaction of Mg(OH)2 and HCI is shown in Equation 1.

word image 1330 + 2 HCl(aq) word image 1331

MgC12(aq) +2 H20(1) (Eq. 1)

word image 1332 The abbreviations in parentheses following each of the chemical formulas indicate the physical state of each word image 1333 reactant and product. The meanings of the four abbræ viations commonly used in equations are summarized in Table 1.

Table 1 The meanings of physical-state abbreviations used in chemiæl equations

abbreviavon meaning

aq substance is dissolved in water substance is a gas at reaction temperature and pressure substance is a pure liquid at reaction temperature and pressure s substance is a solid tiat is in fre reaction mixture

 

word image 1334

47

REAC 422: Studying Chemical Reactions and Writing Chemical Equations

7Ype Ill: Single Displacement Reactions

Tho 2 that appears In front of HCI and 1-120 Is called When one element displaces another element

a coefflclent; It Indicates that two HCI molecules are consumed and two 1-120 molecules are formed In the reaction. Coefficients are used to balance an equation so that tho reaction Involves only a rearrangement of the reactant atoms to form products. When no coefficient is shown, as is the case with Mg(OH)2 and MgC12 in Equation 1, a coefficient of 1 is understood.

The reaction of iron (Fe) with oxygen (02) to form Iron(lll) oxlde (F0203, ferric oxide) is another familiar reaction. The common name for Fe203 Is rust. The chemical equation for this reaction ts given in Equation 2.

4 Fe(s) +3 02(g) 2 Fe203(s)word image 1335

Notice an Important difference between Equations I and 2. tn the first reaction, two reactants produce two products whereas In the second reaction, two reactants produce only one product.

Classifying Chemical Reactions

Many chemical reactions are conveniently classified as one of four major types. This classification is based on the type of chemical transformation that occurs.

7Ype l: Combination, Synthesis, or

Formatlon Reactions

As the name suggests, a combination, or syntheSIS reactlon, occurs when two substances combine to

word image 1336

form a compound. The reaction In Equation 2 is a combination reaction. Equation 3 is a generalized combination

reaction, while Equations 4—6 are specific examples. word image 1337

A + B * AB word image 1338

8 Mg(s) + 8 Mgs(s) (Eq. 4)

2 ca(s) + 02(g) -i 2 ca0(s) word image 1339

H2(g) + C12(g) 2 HCl(g) word image 1340

7Ype Il: Decomposltlon Reactions

A deeomposltlon reaction occurs when a compound breaks apart to form two or more products. Equation 7 shows a generalized example, while Equations 8—10 give specific examples.

word image 1341 word image 1342 (Eq. 7)

2 Hg0(s) 2 Hg(l) + 02(g) (Eq. 8)

from a compound, we call the pFocess a single dis. placement reaction. Equation 11 shows a general, Ized example, and Equations 12 and 13 show specific examples.

word image 1344

(Eq. 11)

sn(s) + 2 AgN03(aq) word image 1346 word image 1347 +2 Ag(s)

(Eq. 12)

word image 1349 2 Al(s) + 6 HN03(aq) +3 H2(g) (Eq 13)

2

When we write (aq) after the formula of an ionic compound, we mean that the ions are individuqlty sOIvated by water. We could rewrite Equation 12 as Equation 14 to show the solvation of the ions involved:

Sn(s) + 2 Ag+(aq) + 2 N03¯(aq) word image 1350

word image 1352 +2 NOö(aq) +2 Ag(s) (Eq. 14)

Equation 14 is the complete ionic equation for the reaction. Note that the solvated nitrate ion (NOD appears on both sides of Equation 14. Therefore it is not directly involved in the chemical reaction. We call such ions spectator ions. Thus, Equation 14 may be rewritten with the NOE ion omitted; as In Equation 15.

Sn(s) + 2 Ag+(aq) Sn2+(aq) + 2 Ag(s) (Eq. 15) Equation 15 is the net ionic equation forthis reaction.

Type IV: Double Displacement, Double word image 1353

Replacement, or Metathesis Reactions word image 1354

A double displacement reaction occurs when atoms or ions in two or more different substances change places to form new compounds. One of the new compounds formed Is usually either a solid, called a precipItate, a slightly dissociated compound, such as a gas. A doubte displacement reaction involving the formation of a precipitate is often called a precipitation reaction. Equation 16 is a general example; Equation 17 is a specific example.

word image 1357 (Eq. 16)

The complete and net ionic equations NaN03(aq) for the reaction (Eq. 17)in

Fquatlon 17 are shown in Equations 18 and 19,

BaC03(s) Ba0(s) + C02(g)

(Eq. 9)

word image 1359

Pb2+(aq) + 2 NOö(aq) + 2 Na+(aq) + 2 ct-(aq) -+

2 Pb02(s) -9 2 Pb0(s) + 02(g)

(Eq. 10)

 

word image 1360 PbC12(s) +2 2 NOö(aa) (Ea. 18)

C 422: Studying Chemical Reactions and Writing Chemical Equations

If you spill any reagent on your hands or skin, immediately wash with ample amounts of running water.

Pb2+(aq) + 2 cr(aq) -4 PbC12(s) (Eq. 19)

Note: The numbers appearing in parentheses indicate the specific lines on your Data Sheet on

word image 1362

which the indicated data should be entered.

In this experiment, you will mix different elements and/or components in solution. In some cases, you will heat th’e mixtures to promote a reaction. You will observe the appearance of the reactants and of the products, and you will determine which type of reaction occurs in each case. You will also write the chemical equations for the reactions you perform. The chemical symbols for the elements and compounds you will work with are listed in Table 2. I. Reacting Mg with HCI Solution

Table 2 Chemical symbols for the elements and compounds used in this experiment

name chemical symbol

ammonia NH3 ammonium carbonate (NH4)2C03 carbon(lV) oxide (carbon dioxide) C02

word image 1364 copper cu copper(ll) sulfate (cupric sulfate) cuS04 copper(ll) sulfate pentahydrate CuSOC 5 H20 • hydrochloric acid iron iron(lll) chloride (ferric chloride) lead(ll) nitrate magnesium Mg oxygen 02 potassium iodide word image 1365 word image 1367 sodium hydrpxide NaOH

sulfur

Caution: The gas produced by the reaction of Mg and HCI solution is flammable. Be sure that there are no Bunsen burner flames in the area where you are performing this reaction.

    1. word image 1368 Transfera 0.5-cm piece of Mg ribbon to the bottom of a clean test tube.

Record on your Data Sheet your description of the appearance of the Mg (1).

    1. word image 1370 word image 1371 word image 1372 word image 1373 word image 1375 word image 1377 word image 1379 word image 1380 word image 1382 word image 1383 Measure 2 mL of 0.1M HCI solution in a 10-mL graduated cylinder. Record on your Data Sheet your description of the appearance ofthe HCI solution (2).

Transferthe HCI solution to the test tube containing the Mg. Observe the reaction mixture for evidence of a chemical reaction.

Record on your Data Sheet any evidence that a chemical reaction has occurred (3).

    1. Transfer the contents of your test tube to the container specified by your laboratory instructor and la word image 1384 be!ed “Discarded Mg—HCI Reaction Mixtures.”

Procedure

Note: Your laboratory instructor will .tell you whether or not you should complete Step 4 before proceeding to Step 5.

Chemical Alert

ammonia—toxic and corrosive ammonium carbonate—irritant

0.1 M copper(ll) sulfate—toxic and Irritant

O. 1 M hydrochloric acid—toxic and corrosive

O. 1 M iron(lll) chloride—corrosive

0.1 M lead(ll) nitrate—toxic, irritant, and oxidant

magnesium—flammable

0.1 M potassium iodide—toxic and irritant

0.1 M sodium hydroxide—toxic and corrosive sulfur—irritant

 

Caution: Wear departmentally approved eye protection while doing this experiment.

Caution: Lead nitrate and KI solutions are toxic. Immediately notify your laboratory instructor if any solution spills.

4. Write on your Data Sheet the complete and net ionic equations for the reaction of Mg with HCI solution (4, 5). Indicate which of the four general reaction types is represented by this reaction (6). word image 1386

Il. Reacting word image 1387 Solution with Kl

Solution

49

A. Neidig

word image 1343

editor:

H.

Studying Chemical Reactions and Writing

Chemical Equations

prepared by M. L. Gillette, Indiana University/Kokomo and H. Anthony Neidig, Lebanon Valley College

 

PurpoSe of the Experiment

Describe chemical reactions by writing chemical equations based on laboratory.observations and information about reactions of different substances.

Background Information

word image 1345 word image 1346 word image 1347 word image 1348 word image 1350 The human digestive process depends on a high concentration of hydrochloric acid (HCI) in the stomach. Sometimes the HC} concentration becomes too high, which causes discomfort (“acid stomach’). When this condition occurs, many people take antac word image 1351 ids to help neutralize the excess acid. The active ingredient in many antacids is magnesium hydroxide, Mg(OH)2. When solid Mg(OH)2 mixes with HCI solution, a chemical reaction occurs. We can describe this reaction as: Mg(OH)2 reacts with HCI to produce magnesium chloride (MgC12) and water (H20).

We can make the same statement more concisely by writing a chemical equation for the reaction. A chemical equation, the symbolic description of a chemical process, shows the substances that react, the reactants, and the substances that form as a result of a chemical change, the products. An arrow indicates that the process occurs and is read ‘yields.” The chemical equation for the reaction of Mg(OH)2 and HCI is shown in Equation 1.

word image 1353 + 2 HCl(aq) word image 1355

MgC12(aq) +2 H20(1) (Eq. 1)

word image 1356 The abbreviations in parentheses following each of the chemical formulas indicate the physical state of each word image 1358 reactant and product. The meanings of the four abbræ viations commonly used in equations are summarized in Table 1.

Table 1 The meanings of physical-state abbreviations used in chemiæl equations

abbreviavon meaning

aq substance is dissolved in water substance is a gas at reaction temperature and pressure substance is a pure liquid at reaction temperature and pressure s substance is a solid tiat is in fre reaction mixture

 

word image 1361

47

REAC 422: Studying Chemical Reactions and Writing Chemical Equations

7Ype Ill: Single Displacement Reactions

Tho 2 that appears In front of HCI and 1-120 Is called When one element displaces another element

a coefflclent; It Indicates that two HCI molecules are consumed and two 1-120 molecules are formed In the reaction. Coefficients are used to balance an equation so that tho reaction Involves only a rearrangement of the reactant atoms to form products. When no coefficient is shown, as is the case with Mg(OH)2 and MgC12 in Equation 1, a coefficient of 1 is understood.

The reaction of iron (Fe) with oxygen (02) to form Iron(lll) oxlde (F0203, ferric oxide) is another familiar reaction. The common name for Fe203 Is rust. The chemical equation for this reaction ts given in Equation 2.

4 Fe(s) +3 02(g) 2 Fe203(s)word image 1363

Notice an Important difference between Equations I and 2. tn the first reaction, two reactants produce two products whereas In the second reaction, two reactants produce only one product.

Classifying Chemical Reactions

Many chemical reactions are conveniently classified as one of four major types. This classification is based on the type of chemical transformation that occurs.

7Ype l: Combination, Synthesis, or

Formatlon Reactions

As the name suggests, a combination, or syntheSIS reactlon, occurs when two substances combine to

word image 1365

form a compound. The reaction In Equation 2 is a combination reaction. Equation 3 is a generalized combination

reaction, while Equations 4—6 are specific examples. word image 1366

A + B * AB word image 1369

8 Mg(s) + 8 Mgs(s) (Eq. 4)

2 ca(s) + 02(g) -i 2 ca0(s) word image 1370

H2(g) + C12(g) 2 HCl(g) word image 1371

7Ype Il: Decomposltlon Reactions

A deeomposltlon reaction occurs when a compound breaks apart to form two or more products. Equation 7 shows a generalized example, while Equations 8—10 give specific examples.

word image 1372 word image 1374 (Eq. 7)

2 Hg0(s) 2 Hg(l) + 02(g) (Eq. 8)

from a compound, we call the pFocess a single dis. placement reaction. Equation 11 shows a general, Ized example, and Equations 12 and 13 show specific examples.

word image 1376

(Eq. 11)

sn(s) + 2 AgN03(aq) word image 1378 word image 1379 +2 Ag(s)

(Eq. 12)

word image 1381 2 Al(s) + 6 HN03(aq) +3 H2(g) (Eq 13)

2

When we write (aq) after the formula of an ionic compound, we mean that the ions are individuqlty sOIvated by water. We could rewrite Equation 12 as Equation 14 to show the solvation of the ions involved:

Sn(s) + 2 Ag+(aq) + 2 N03¯(aq) word image 1382

word image 1383 +2 NOö(aq) +2 Ag(s) (Eq. 14)

Equation 14 is the complete ionic equation for the reaction. Note that the solvated nitrate ion (NOD appears on both sides of Equation 14. Therefore it is not directly involved in the chemical reaction. We call such ions spectator ions. Thus, Equation 14 may be rewritten with the NOE ion omitted; as In Equation 15.

Sn(s) + 2 Ag+(aq) Sn2+(aq) + 2 Ag(s) (Eq. 15) Equation 15 is the net ionic equation forthis reaction.

Type IV: Double Displacement, Double word image 1384

Replacement, or Metathesis Reactions word image 1385

A double displacement reaction occurs when atoms or ions in two or more different substances change places to form new compounds. One of the new compounds formed Is usually either a solid, called a precipItate, a slightly dissociated compound, such as a gas. A doubte displacement reaction involving the formation of a precipitate is often called a precipitation reaction. Equation 16 is a general example; Equation 17 is a specific example.

word image 1388 (Eq. 16)

The complete and net ionic equations NaN03(aq) for the reaction (Eq. 17)in

Fquatlon 17 are shown in Equations 18 and 19,

BaC03(s) Ba0(s) + C02(g)

(Eq. 9)

word image 1389

Pb2+(aq) + 2 NOö(aq) + 2 Na+(aq) + 2 ct-(aq) -+

2 Pb02(s) -9 2 Pb0(s) + 02(g)

(Eq. 10)

 

word image 1390 PbC12(s) +2 2 NOö(aa) (Ea. 18)

C 422: Studying Chemical Reactions and Writing Chemical Equations

If you spill any reagent on your hands or skin, immediately wash with ample amounts of running water.

Pb2+(aq) + 2 cr(aq) -4 PbC12(s) (Eq. 19)

Note: The numbers appearing in parentheses indicate the specific lines on your Data Sheet on

word image 1391

which the indicated data should be entered.

In this experiment, you will mix different elements and/or components in solution. In some cases, you will heat th’e mixtures to promote a reaction. You will observe the appearance of the reactants and of the products, and you will determine which type of reaction occurs in each case. You will also write the chemical equations for the reactions you perform. The chemical symbols for the elements and compounds you will work with are listed in Table 2. I. Reacting Mg with HCI Solution

Table 2 Chemical symbols for the elements and compounds used in this experiment

name chemical symbol

ammonia NH3 ammonium carbonate (NH4)2C03 carbon(lV) oxide (carbon dioxide) C02

word image 1392 copper cu copper(ll) sulfate (cupric sulfate) cuS04 copper(ll) sulfate pentahydrate CuSOC 5 H20 • hydrochloric acid iron iron(lll) chloride (ferric chloride) lead(ll) nitrate magnesium Mg oxygen 02 potassium iodide word image 1393 word image 1394 sodium hydrpxide NaOH

sulfur

Caution: The gas produced by the reaction of Mg and HCI solution is flammable. Be sure that there are no Bunsen burner flames in the area where you are performing this reaction.

    1. word image 1395 Transfera 0.5-cm piece of Mg ribbon to the bottom of a clean test tube.

Record on your Data Sheet your description of the appearance of the Mg (1).

    1. word image 1396 word image 1397 word image 1398 word image 1399 word image 1400 word image 1401 word image 1402 word image 1403 word image 1404 word image 1405 Measure 2 mL of 0.1M HCI solution in a 10-mL graduated cylinder. Record on your Data Sheet your description of the appearance ofthe HCI solution (2).

Transferthe HCI solution to the test tube containing the Mg. Observe the reaction mixture for evidence of a chemical reaction.

Record on your Data Sheet any evidence that a chemical reaction has occurred (3).

    1. Transfer the contents of your test tube to the container specified by your laboratory instructor and la word image 1406 be!ed “Discarded Mg—HCI Reaction Mixtures.”

Procedure

Note: Your laboratory instructor will .tell you whether or not you should complete Step 4 before proceeding to Step 5.

Chemical Alert

ammonia—toxic and corrosive ammonium carbonate—irritant

0.1 M copper(ll) sulfate—toxic and Irritant

O. 1 M hydrochloric acid—toxic and corrosive

O. 1 M iron(lll) chloride—corrosive

0.1 M lead(ll) nitrate—toxic, irritant, and oxidant

magnesium—flammable

0.1 M potassium iodide—toxic and irritant

0.1 M sodium hydroxide—toxic and corrosive sulfur—irritant

 

Caution: Wear departmentally approved eye protection while doing this experiment.

Caution: Lead nitrate and KI solutions are toxic. Immediately notify your laboratory instructor if any solution spills.

4. Write on your Data Sheet the complete and net ionic equations for the reaction of Mg with HCI solution (4, 5). Indicate which of the four general reaction types is represented by this reaction (6). word image 1407

Il. Reacting word image 1408 Solution with Kl

Solution

49

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