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CHE 1302 Lecture Notes - Lecture 21: Manganese

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greyduck910
20 Dec 2017
School
Baylor University
Department
Chemistry
Course
CHE 1302
Professor
Mc Grath

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Document Summary

Cl2 (in acidic solution: balance mass (here, # cl atoms on each side): Now we need to balance o and h and then balance charge using e : add h+ to mop up the o atoms and make h2o: Cl2 + 8h2o: add e to balance the charge. But 2cl atoms are reduced so 14e are needed . Mno2 (in basic solution: balance as if acidic (make sure you can do this! Mno2 + 2h2o: neutralize h+ add as many oh as there are h+, to each side: + 3e mno2 + 2h2o + 4oh : make h2o molecules: + 3e mno2 + 2h2o + 4oh : simplify: Check: mass and charge are balanced and (oxidation numbers) mn7+ + 3e mn4+ . Use the half-reaction method to balance the equation below for the reaction of manganese (iv) oxide with hydrochloric acid. Mno2(s) + hcl(aq) mncl2(aq) + cl2(g) + h2o(l)

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Related Questions

Question1
Marks: 1
What is the oxidation state assigned to Mn in potassium permanganate, KMnO4? (Recall that answers must be numbers, that is, F is -1 not 1- in HF.)
Answer:
Question2
Marks: 1

What is the oxidation state assigned to O in hydorgen peroxide, H2O2?
Answer:
Question3
Marks: 1
What is the oxidation state assigned to B in B(OH)3?
Answer:
Question4
Marks: 1
What is the oxidation state assigned to N in the nitrite ion, NO2-?
Answer:
Question5
Marks: 1

What is the oxidation state assigned to N in NH2-?
Answer:
Question6
Marks: 1
What is the oxidation state assigned to Cr in zinc dichromate, ZnCr2O7?
Answer:
Question7
Marks: 1

What is the oxidation state assigned to Xe in XeO2F2?
Answer:
Question8
Marks: 1
What is the oxidation state assigned to Xe in XeO3F2?
Answer:
Question9
Marks: 1
Easy: Complete and balance the following redox reaction in acid solution:

Cl2(g) + Br-(aq) ? Cl-(aq) + Br2(l)

For the balanced oxidation half-reaction, how many electrons are produced? How many bromide ions are there? (Always use smallest integer coefficients.)
Choose at least one answer.
a. 1 e-
b. 2 e-
c. 1 Br-
d. 2 Br-
Question10
Marks: 1
How many chlorine molecules are in the balanced equation?
Answer:
Question11
Marks: 1
Medium: Complete and balance the following redox reaction in acid solution:

Cu(s) + NO3-(aq) ? NO(g) + Cu2+(aq)

For the balanced reduction half-reaction, how many electrons are needed? How many H+ ions are there?
Choose at least one answer.
a. 1 e-
b. 2 e-
c. 3 e-
d. 4 e-
e. 1 H+
f. 2 H+
g. 3 H+
h. 4 H+
Question12
Marks: 1
How many H+ ions are in the balanced equation?

(If the H+ ions are the left side (reactant), write it as a positive number. If they are the right side (product), write it as a negative number.)
Answer:
Question13
Marks: 1
Complete and balance the following redox reaction in acid solution:

MnO4-(aq) + C2H2O4(aq) ? Mn2+(aq) + CO2(g)

For the balanced oxidation half-reaction, how many electrons are produced? How many H+ ions are there?
Choose at least one answer.
a. 1 e-
b. 2 e-
c. 3 e-
d. 4 e-
e. 1 H+
f. 2 H+
g. 3 H+
h. 4 H+
Question14
Marks: 1
How many H+ ions are in the balanced equation?

(If the H+ ions are the left side (reactant), write it as a positive number. If they are the right side (product), write it as a negative number.)
Answer:
Question15
Marks: 1
Complete and balance the following redox reaction in basic solution:

ClO-(aq) + CrO2-(aq) ? Cl-(aq) + CrO42-(aq)

For the balanced oxidation half-reaction, how many electrons are produced? How many OH- ions are there?

Hint given in the general feedback.
Choose at least one answer.
a. 1 e-
b. 2 e-
c. 3 e-
d. 4 e-
e. 1 OH-
f. 2 OH-
g. 3 OH-
h. 4 OH-
Question16
Marks: 1
How many OH- ions are in the balanced equation?

(If the OH- ions are the left side (reactant), write it as a positive number. If they are the right side (product), write it as a negative number.)

Having trouble with thse questions. Please answer all questions correctly. Will provide a thumbs up.

1.Which of these equations is the balanced reaction between nitrous acid solution and solidmagnesium hydroxide ?

A.2NH3(aq) + MgOH (s) Mg(NH4)2(aq) + 2 H2O(l)

B.2HNO2(aq) + Mg(OH)2(s) Mg(NO2)2(aq) + 2 H2O(l)

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

D.2HNO2(aq) + MgOH (s) Mg(NO3)2(s) + 2H2O(l)

2.Balance the following chemical equation:

C3H7OH(l) + O2(g)CO2(g) + H2O(g)

a. C3H7OH(l) + 4 O2(g)3 CO2(g) + 4 H2O(g)

b.2 C3H7OH(l) + 9 O2(g)6 CO2(g) + 8 H2O(g)

c.C3H7OH(l) + 5 O2(g)3 CO2(g) + 4 H2O(g)

d.C3H7OH(l) + O2(g)CO2(g) + H2O(g)

3.Which species would be considered a spectator ion based on the following equation?

Ba2+ + 2NO3− + 2Na+ + SO42- → BaSO4(s) + 2NO3− + 2Na+

SO42-

2NO3−

Ba2+

BaSO4

4.Barium sulfate is often ingested to aid in the diagnosis of GI tract disorders. The equation for its production is Ba2+ + SO42- → BaSO4(s). What type of equation is this?

A full equation

A net ionic equation

A total ionic equation

An oxidation-reduction equation

5.Which species is being reduced in this reaction?

CuO(s) + H2(g) Cu(s) + H2O(g)

H2O

CuO

Cu

H2

6.Which of the following is an oxidizing agent?

H2

NH3

O2

H2O

7.The following chemical equation,

HC2H3O2(aq) + KOH(aq) KC2H3O2(aq) + H2O(l),

is an example of a(n) _______ reaction.

a.oxidation-reduction and acid-base

b.acid-base

c.precipitation

d.oxidation-reduction and precipitation

e.oxidation-reduction

8.What substance is oxidized in the following reaction?

4HCl + MnO2 → Cl2 + 2H2O + MnCl2

a.Mn in MnO2

b.O in MnO2

c.Cl in HCl

d.H in HCl

9.What is the reducing agent in the following reaction?

4HCl + MnO2 → Cl2 + 2H2O + MnCl2

Cl2

MnCl2

HCl

MnO2

10.All redox reactions involve oxygen.

True

False

11.The term formula weight can be used with respect to which of the following?

A.ionic compounds

B.covalent compounds

C.both a and b

D.neither a nor b

12.What is the molecular weight of ibuprofen, C13H18O2?

A.206.3 amu

B.377.7 amu

C.29.0 amu

D.289.4 amu

13.The mass of an atom of 12C is exactly 12 atomic mass units. Which of the following describes a mole of 12C atoms?

A.a sample which weighs exactly 12 atomic mass units

B.a sample which contains 6.02 × 1023 atoms of 12C

C.both a and b

D.neither a nor b

14.The mass of an atom of 12C is exactly 12 atomic mass units. Which of the following describes a mole of 12C atoms?

A.a sample which contains 6.02 × 1023 atoms of 12C

B.a sample which weighs exactly 12.011 grams

C.both a and b

D.neither a nor b

15.What is the molar mass of water, H2O?

A.18.02 g

B.18.02 amu

C.17.01 g

D.17.01 amu

16.What is the molar mass of glucose, C6H12O6?

A.180.2 amu

B.180.2 g

C.60.05 amu

D.60.05 g

17.In the reaction 2H2O → 2H2 + O2, 2.0 mol water will produce how many grams of O2?

32

64

16

36

18.In the reaction 2CH4 + O2 → 2CO + 4H2, how many molecules of CO will be produced by the complete reaction of 1.60 grams of CH4?

3.01 × 1022

2.00

12.0 × 1023

6.02 × 1022

19.Suppose 2.43 g of magnesium is reacted with 3.20 g of oxygen: 2Mg + O2 → 2MgO. How many grams of MgO will be produced?

1.27

4.03

5.63

8.06

20.Which of the following conversion factors would allow one to calculate the amount of PbI2produced from a given amount of NaI in the following unbalanced reaction?

Pb(NO3)2 + Nal → Pbl2 + NaNO3

a.

b.

c.

d.

21.The unbalanced equation for the reduction of copper(I) sulfide with oxygen is given below. What mass of copper is produced from the reduction of 7.50 g Cu2S?

Cu2S(s) + O2(g) Cu(s) + SO2(g)

18.8 g

5.99 g

1.50 g

9.39 g

2.99 g

22.How many grams of aluminum oxide are produced by the complete reaction of 19.8 g aluminum with excess oxygen?

10.5 g aluminum oxide

37.4 g aluminum oxide

49.9 g aluminum oxide

74.8 g aluminum oxide

23.If 5 grams of CO and 5 grams of O2 are combined according to the reaction, which is the limiting reagent?

2CO + O2 → 2CO2

O2

CO and O2

CO2

CO

24.In an industrial process, nitrogen is reacted with hydrogen to produce ammonia. The percent yield of this particular process is 26%. How much hydrogen is needed to produce 4.8 kg ammonia?

1.5 kg

7.0 kg

0.85 kg

3.3 kg

25.A percentage yield greater than 100% has been reported in a scientific paper you are assigned to read. What would be a reasonable explanation for this?

a. The product was measured more than once.

b. It must be a typographical error since yields can't exceed 100%.

c. A lack of training of the professor who published the study.

d. Small measurement errors could have caused this to occur.

26.In an industrial process, nitrogen is reacted with hydrogen to produce ammonia. The percent yield of this particular process is 24.8%. How much hydrogen is needed to produce 3.7 kg ammonia?

1.8 kg

1.2 kg

4.4 kg

12 kg

2.7 kg

27.The following reaction has a percent yield of 90.5%. How many grams of carbon dioxide are produced from 78.5 g calcium carbonate via this reaction?

2 HNO3(aq) + CaCO3(aq) Ca(NO3)2(aq) + H2O(l) + CO2(g)

34.5 g

21.6 g

38.1 g

31.2 g

28.When gas molecules dissolve in liquids to form a saturated system, the process is usually

exothermic.

endothermic.

independent of the nature of the liquid.

temperature independent.

29.The reaction below would be considered.

CaCO3 + heat → CaO + CO2

an exothermic combination.

an exothermic decomposition.

an endothermic combination.

an endothermic decomposition.

30.The combustion of one mole of propane, C3H8, releases 531 kcal. How much heat is released by the combustion of 1.20 moles of propane?

A.584 kcal

B.690 kcal

C.443 kcal

D.637 kcal

31.The combustion of one mole of propane, C3H8, releases 531 kcal. How much heat is released by the combustion of 4.40 g of propane?

A.531 kcal

B.5.31 × 104 kcal

C.53.1 kcal

D.5.31 × 103 kcal

32.Metabolism of one mole of glucose, C6H12O6, releases 670 kcal. How much heat is released by the combustion of 0.300 moles of glucose?

A.201 kcal

B.2.41 × 103 kcal

C.186 kcal

D.2.23 × 103 kcal

33.Metabolism of one mole of glucose, C6H12O6, releases 6.70 × 102 kcal. How much heat is released by the combustion of 50.0 g of glucose?

A.201 kcal

B.2.41 × 103 kcal

C.186 kcal

D.2.23 × 103 kcal

1. (1 point) What are transferred in an oxidation-reduction reaction? *

• atoms

• electrons

• ions

• protons

2. (1 point) In the reaction of beryllium with fluorine, which atom is oxidized? *

• fluorine

• beryllium

• neither of them

• both of them

3. (1 point) Ag - - > Ag ^+ +1 e^- This equation represents the type of reaction called _____. *

• hydrolysis

• oxidation

• redox

• reduction

4. (1 point) What is the reducing agent in the following reaction? 2K + S - - > K2S *

• K

• S

• K2S

• None of the above

5. (1 point) The oxidation number of oxygen when it is in a compound other than a peroxide is ____. *

• -2

• -1

• 0

• +2

6. (1 point) What is the oxidation number for each atom in NH4F? *

• N=+3, H=-4, F=+1

• N=-3, H=+1, F=-1

• N=+3, H+1, F=-1

• N=-3, H=-1, F=+1

7. (1 point) Which atom has a change in oxidation number of +4 in the following redox reaction?K2Cr2O7 + H2O + S - - > KOH + Cr2O3 + SO2 *

• K

• Cr

• O

• S

Metal activity series for question 8

8. (1 point) Of the following metals, which ions are most easily reduced? Use the above table to answer the question. *

• magnesium

• lead

• copper

• sodium

9. (1 point) In a zinc-copper cell, Zn(s) | Zn^+2(1M) || Cu^+2(1M) | Cu(s), which electrode is positive? *

• Cu^+2

• Cu(s)

• Zn(s)

• Zn^+2

10. (1 point) How must a redox reaction that is to be used as a source of electrical energy be set up? *

• One half reaction must involve two metals.

• Two half reactions must use a metal wire electrodes.

• One half reactions must involve more than one electron.

• Two half reactions must be physically separated.

11. (1 point) In a voltaic cell at which electrode does reduction occur? *

• anode only

• cathode only

• both anode and cathode

• Either anode or cathode , depending on the metal

12. (1 point) What assures that there is no charge build up in a voltaic cell as oxidation and reduction occur? *

• one of the half cells

• the electrolyte solutions

• the moving electrons

• the salt bridge

13. (1 point) In the most common dry cell what material is the electrode that is the center rod made of? *

• copper

• graphite

• lead

• zinc

14. (1 point) To charge a lead storage battery you must ________. *

• apply a direct current to it.

• hold a magnet close to it.

• Use alternating current through it.

• increase the oxygen in it.

15. (1 point) In a hydrogen- oxygen fuel cell ______________. *

• hydrogen diffuses through the cathode.

• hydrogen and oxygen are mixed before entering the anode.

• oxygen diffuses through the anode.

• oxygen diffuses through the cathode.

16. (1 point) When electrical energy is used to cause a chemical reaction we call this process _____. *

• electronation

• electrolysis

• hydration

• reduction

17. (1 point) Which of the following is true about an electrolytic cell? *

• It changes chemical energy into electrical energy.

• It is the type of cell used in electrocution

• It uses an electric current to make a nonspontaneous reaction go.

• All of the above

18. (1 point) The products formed in the net reaction of the electrolysis of water are ____. *

• aqueous hydrogen ion and hydroxyl ion

• hydrogen gas and oxygen gas

• hydrogen gas and liquid oxygen

• water vapor

19. (1 point) What occurs in electroplating? *

• decomposition of an ionic compound

• decomposition of a salt layer

• deposition of a metal layer on a material

• deposition of a salt layer on a metal

Open response Questions : Answer questions 20 through 22 in complete sentences

20. ( 5 points) Write the equation for the reaction of calcium and oxygen ( 1 point). Write the oxidation numbers for both the reactants and the products ( 2 points) What is the reducing agent and why? ( 2 points)

21. ( 5 points) Tell how a voltaic cell works. Be sure to mention the various parts of the voltaic cell and what they have to do with how it works.

22. (4 points) What are the signs given to the electrodes in both the voltaic and electrolytic cells? What reaction (oxidation or reduction) is occurring at each?