Balancing Equations

Monday, November 28Monday, November 28thth

Bellwork:

What is the chemical in turkeys that supposedly causes fatigue?


Bellwork: Tryptophan

Tryptophan is an essential Amino Acid. It is a component of many plant and animal proteins, and a normal part of the diet that humans must get from outside sources. It is a precursor (starting material) for serotonin (which aids sleep and anxiety). Foods that are considered sources of tryptophan are dairy products, beef, poultry, barley, brown rice, fish, soybeans, and peanuts.

Tryptophan is a natural sedative. It is normally found in turkey meat, and many people believe it to be the cause of a sleepiness common after a Thanksgiving feast.

Now, does the tryptophan in turkey make you sleepy after eating a big Thanksgiving turkey dinner?

Sorry to say, that if you're looking for the sedative effect, it's unlikely you'll get it from eating meats like turkey. Tryptophan doesn't act on the brain unless you take it on an empty stomach with no protein present. So it probably isn't at fault for the sudden drowsiness that hits right after the meal when the football games come on, and the dishes are waiting!

It's more likely due to overeating - not just turkey, but also mashed potatoes, ham, creamed onions, cranberries, sweet potatoes, peas, stuffing (or dressing, if you prefer), carrots, bread, pies, and whipped cream - all of which have the effect of puling the blood away from your brain to help your digestive tract do it's work, and the sugar/insulin effect.


Bellwork:• Write chemical equations for the following reactions. Include

symbols for physical states when indicated.

• A) Solid calcium reacts with solid sulfur, S8, to produce solid calcium sulfide.

• B) Hydrogen gas reacts with fluorine gas to produce hydrogen monofluoride gas.

• C) Solid aluminum metal reacts with aqueous zinc(II) chloride to produce solid zinc metal and aqueous aluminum chloride.

Ca(s) + S8(s) CaS(s)

H2(g) + F2(g) HF(g)

Al(s) + ZnCl2(aq) Zn(s) + AlCl3(aq)

Balancing Chemical Balancing Chemical EquationsEquations

Balance equations by changing coefficients …

… never by changing formula subscripts


1. Balance Metals 2. Balance Nonmetals (except polyatomic ions, oxygen, and hydrogen)

3. Balance Polyatomic ions

4. Balance Oxygen

5. Balance Hydrogen

6. Recount All Atoms

7. Reduce


The order in which these steps are performed is important.While shortcuts are possible, following these steps in order is the best way to be sure you are correct.


1 O

2 H

2 O

2 HNOT BALANCED

water hydrogen

oxygen

+

H2O(l) H2(g) + O2(g)2

2 O

2 HNOT BALANCED2 O

4 H

water


hydrogen

oxygen

+

H2O(l) H2(g) + O2(g)2 2

H2O(l) H2(g) + O2(g)

2O

4 H

2O

4 HBALANCED

2 2

4. Always go back and double check!

**

Balancing Equations

water


hydrogen

oxygen

+

http://www.howe.k12.ok.us/~jimaskew/cequa.htm

Zn(s) ZnCl2(aq) + H2(g)HCl(aq)+

1 Zn

1 Cl

1 H

1 Zn

2 Cl

2 HNOT BALANCED

2

Sample Problem 8-3Sample Problem 8-3•The reaction of zinc with aqueous

hydrochloric acid (hydrogen monochloride) produces a solution of zinc(II) chloride and hydrogen gas. Write a balanced chemical equation for the reaction.

Zn(s) ZnCl2(aq) + H2(g)HCl(aq)+

1 Zn

2 Cl

2 H

1 Zn

2 Cl

2 H

2

BALANCED

4. Always go back and double check!

***

Sample Problem 8-3Sample Problem 8-3•The reaction of zinc with aqueous

hydrochloric acid (hydrogen monochloride) produces a solution of zinc(II) chloride and hydrogen gas. Write a balanced chemical equation for the reaction.

Sample Problem 8-4Sample Problem 8-4•Solid aluminum carbide, Al4C3, reacts with

water to produce methane gas, CH4, and solid aluminum hydroxide. Write a balanced chemical equation for this reaction.

Al4C3(s) H2O(l)+ CH4(g) + Al(OH)3(s)



Al4C3(s)

4 Al

3 C

1 OH

1 H

1 Al

1 C

3 OH

4 H

HOH(l)+ CH4(g) + Al(OH)3(s)4



Al4C3(s)

4 Al

3 C

1 OH

1 H

4 Al

1 C

12 OH

4 H

HOH(l)+ CH4(g) + Al(OH)3(s)43



Al4C3(s)

4 Al

3 C

1 OH

1 H

4 Al

3 C

12 OH

12 H

HOH(l)+ CH4(g) + Al(OH)3(s)4312



Al4C3(s)

4 Al

3 C

12 OH

12 H

4 Al

3 C

12 OH

12 H

HOH(l)+ CH4(g) + Al(OH)3(s)4312

*

BALANCED***

Sample Problem 8-5Sample Problem 8-5•Write the balanced chemical equation for

the following reactions:• A) Magnesium and hydrochloric acid react to produce

magnesium chloride and hydrogen.

Mg(s)

1 Mg

1 Cl

1 H

1 Mg

2 Cl

2 H

HCl(aq)+ MgCl2(aq)+ H2(g)2


the following reactions:• A) Magnesium and hydrochloric acid react to produce

magnesium chloride and hydrogen.

Mg(s)

1 Mg

2 Cl

2 H

1 Mg

2 Cl

2 H

HCl(aq)+ MgCl2(aq)+ H2(g)2

*

BALANCED**


the following reactions:• B) Aqueous nitric acid (HNO3) reacts with solid magnesium

hydroxide to produce aqueous magnesium nitrate and water.

HNO3 (aq) Mg(OH)2(s)+ Mg(NO3)2(aq)+ H2O(l)




HNO3 (aq) Mg(OH)2(s)+ Mg(NO3)2(aq)+HOH(l)




HNO3 (aq)

1 Mg

1 NO3

2 OH

1 H

1 Mg

2 NO3

1 OH

1 H

Mg(OH)2(s)+ Mg(NO3)2(aq)+HOH(l)2




HNO3 (aq)

1 Mg

2 NO3

2 OH

2 H

1 Mg

2 NO3

1 OH

1 H

Mg(OH)2(s)+ Mg(NO3)2(aq)+ HOH(l)2 2




HNO3 (aq)

1 Mg

2 NO3

2 OH

2 H

1 Mg

2 NO3

2 OH

2 H

Mg(OH)2(s)+ Mg(NO3)2(aq

)

+ HOH(l)2

*

BALANCED**

2

*

Sample Problem 8-7Sample Problem 8-7• Aluminum sulfate and calcium hydroxide are used in a

water-purification process. When added to water, they dissolve and react to produce two insoluble products, aluminum hydroxide and calcium sulfate. These products settle out, taking suspended solid impurities with them. Write a balanced chemical equation for the reaction.

Al2(SO4)3(aq

)

Ca(OH)2(aq)+ Al(OH)3(g)+ CaSO4(s

)

2

2 Al

1 Ca

3 SO4

2 OH

1 Al

1 Ca

1 SO4

3 OH



Al2(SO4)3(aq

)


)

32

2 Al

1 Ca

3 SO4

2 OH

2 Al

1 Ca

1 SO4

6 OH



Al2(SO4)3(aq

)


)

32

2 Al

1 Ca

3 SO4

2 OH

2 Al

3 Ca

3 SO4

6 OH

3



Al2(SO4)3(aq

)


)

323

2 Al

3 Ca

3 SO4

6 OH

2 Al

3 Ca

3 SO4

6 OH

****

BALANCED

HW 8-1 248 #1-2 252 #1254 #1

Due: W 11/30

* “Chemical Reactions Quiz” is on F 12/3


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Balancing Equations

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