Quiz about oxidation numbers
Oxidation Numbers: Calculation, Rules, and Examples
Introduction:
Explore the world of oxidation numbers, delving into the intricacies of calculating these essential values in chemical compounds. This lesson provides a comprehensive overview of oxidation numbers, their significance in ionic and covalent compounds, rules for determination, and practical examples.
Uncover the mysteries of redox reactions, learn the steps to calculate oxidation numbers, and understand the role of elements like oxygen, hydrogen, and transition metals. Whether you’re a chemistry enthusiast or a student, this lesson aims to make oxidation numbers more accessible and comprehensible.
Quiz based on oxidation numbers:
Multiple Choice:
1-What does the oxidation number of an atom or ion represent?
a) Mass
b) Electric charge
c) Atomic radius
d) Number of protons
2-In a neutral compound, what is the sum of oxidation numbers for all atoms?
a) -1
b) 0
c) +1
d) It varies
3-If the oxidation number is positive in an ionic compound, what does it indicate?
a) Electron gain
b) Electron loss
c) No electron involvement
d) Covalent bonding
4-What is the oxidation number of hydrogen in most compounds?
a) +1
b) -1
c) 0
d) +2
5-In which compounds does fluorine always have an oxidation number of -1?
a) Fluorides
b) Oxides
c) Superoxides
d) All of the above
True/False:
6-The oxidation number of an element in its elemental state is always zero.
7-In the compound NaCl, the oxidation number of sodium is +1, and chlorine is -1.
8-The sum of oxidation numbers in a polyatomic ion is equal to the overall charge of the ion.
9-Alkali metals (Group 1A) typically have an oxidation number of +2 in compounds.
10-In the reaction N2O4 to NO2, there is no change in the oxidation number of nitrogen.
Fill in the Blank:
11-The oxidation number of oxygen in most compounds is ____________.
12-The oxidation number of sulfur in SO₄²⁻ is ____________.
13-The algebraic sum of the oxidation numbers in a molecule must be ____________ for a neutral molecule.
14-The oxidation number of manganese in MnO₄⁻ is ____________.
15-In a redox reaction, the species getting oxidized is called the ____________ agent.
Short Answer:
15-Explain the significance of oxidation numbers in ionic compounds.
17-Describe the rules for calculating the oxidation numbers of elements.
18-Provide an example of a redox reaction and identify the oxidizing and reducing agents.
19-Calculate the oxidation number of nitrogen in NO₃⁻.
20-Explain why fluorine always has an oxidation number of -1 in compounds.
Calculation:
21-Calculate the oxidation number of sulfur in H₂SO₄.
22-Determine the oxidation number of chlorine in Cl₂O₇.
23-Calculate the change in the oxidation number of carbon in the transformation from CO₂ to CO.
24-Find the oxidation number of phosphorus in H₃PO₄.
25-Calculate the oxidation number of iodine in HIO₄.
The answers
Multiple Choice:
1-Answer: b) Electric charge
2-Answer: b) 0
3-Answer: b) Electron loss
4-Answer: a) +1
5-Answer: d) All of the above
True/False:
6-Answer: True
7-Answer: True
8-Answer: True
9-Answer: False (Alkali metals typically have an oxidation number of +1 in compounds)
10-Answer: True
Fill in the Blank:
11-The oxidation number of oxygen in most compounds is -2.
12-The oxidation number of sulfur in SO₄²⁻ is +6.
13-The algebraic sum of the oxidation numbers in a molecule must be zero for a neutral molecule.
14-The oxidation number of manganese in MnO₄⁻ is +7.
15-In a redox reaction, the species getting oxidized is called the reducing agent.
Short Answer:
15-The significance of oxidation numbers in ionic compounds lies in determining the transfer of electrons between elements, leading to the formation of positive and negative ions (cation and anion).
16-Rules for calculating oxidation numbers include:
The oxidation number of an element in its elemental state is zero.
The sum of oxidation numbers in a neutral compound is zero.
The oxidation number of hydrogen is usually +1.
The oxidation number of oxygen is usually -2, except in peroxides and superoxides.
17-An example of a redox reaction is the following:
Zn+CuSO4→ZnSO4+Cu
18-The reducing agent is zinc (Zn), and the oxidizing agent is copper (Cu).
19-The oxidation number of nitrogen in NO₃⁻ is +5.
20-Fluorine always has an oxidation number of -1 in compounds due to its high electronegativity.
Calculation:
21-The oxidation number of sulfur in H₂SO₄ is calculated as follows:
2(+1)+x+4(−2)=0
Solving for x, we get x=+6.
22-The oxidation number of chlorine in Cl₂O₇ is calculated as follows:
2x+7(−2)=0
Solving for x, we get x=+7.
23-The change in the oxidation number of carbon from CO₂ to CO is calculated as follows:
2x+2(−2)=0
Solving for x, we get x=+2
Therefore, the change is
+4−(+2)=+2
+4−(+2)=+2.
24-The oxidation number of phosphorus in H₃PO₄ is calculated as follows:
3(+1)+x+4(−2)=0
Solving for x, we get x=+5.
25-The oxidation number of iodine in HIO₄ is calculated as follows:
(+1)+x+4(−2)=0
Solving for x, we get x=+7.
Quiz 2 on Oxidation Numbers – Part 2
Multiple Choice:
1-What is the oxidation number of oxygen in peroxides?
a) -1
b) -1/2
c) -2
d) +2
2-In which group do alkali metals (Group 1A) typically have an oxidation number of +1?
a) Group 2A
b) Group 1A
c) Group 3A
d) Group 7A
3-What is the oxidation number of hydrogen in binary compounds with active metals (active metal hydrides)?
a) +1
b) -1
c) 0
d) +2
4-The oxidation number of sulfur in SO₃ (sulfur trioxide) is:
a) +2
b) +4
c) +6
d) -2
5-What is the oxidation number of manganese in MnO₂ (manganese dioxide)?
a) +2
b) +4
c) +6
d) +7
True/False:
6-In polyatomic ions, the sum of oxidation numbers is equal to the charge of the ion.
7-Oxygen in most compounds has an oxidation number of +2.
8-Transition metals in compounds always have a fixed oxidation number.
9-The oxidation number of hydrogen in NaH is -1.
10-The algebraic sum of oxidation numbers of the atoms in a polyatomic ion equals the overall charge of the ion.
Fill in the Blank:
11-The oxidation number of fluorine in compounds is always ____________.
12-Alkaline Earth Metals (Group 2A) typically have an oxidation number of ____________.
13-In HCl, hydrogen has an oxidation number of ____________.
14-The oxidation number of nitrogen in N₂O₅ is ____________.
15-The oxidation number of sulfur in H₂S (hydrogen sulfide) is ____________.
Short Answer:
16-Explain the significance of oxidation numbers in covalent compounds.
17-Provide an example of a compound involving an alkali metal where hydrogen has an oxidation number of -1.
18-Calculate the oxidation number of chlorine in ClO₄⁻ (perchlorate ion).
19-How does the oxidation number of sulfur change in the reaction S₈ to H₂S?
20-Describe the oxidation numbers in a peroxide compound.
The answers
Here are the answers to the second quiz:
Multiple Choice:
1-Answer: b) -1/2
2-Answer: b) Group 1A
3-Answer: b) -1
4-Answer: c) +6
5-Answer: b) +4
True/False:
6-Answer: True
7-Answer: False (Oxygen in most compounds has an oxidation number of -2)
8-Answer: False (Transition metals in compounds can have variable oxidation numbers)
9-Answer: True
10-Answer: True
Fill in the Blank:
11-The oxidation number of fluorine in compounds is always -1.
12-Alkaline Earth Metals (Group 2A) typically have an oxidation number of +2.
13-In HCl, hydrogen has an oxidation number of +1.
14-The oxidation number of nitrogen in N₂O₅ is +5.
15-The oxidation number of sulfur in H₂S (hydrogen sulfide) is -2.
Short Answer:
16-In covalent compounds, oxidation numbers are used to show the electronic shift in the chemical bond between atoms. Positive oxidation numbers indicate a shift towards the less electronegative atom.
17-An example of a compound involving an alkali metal where hydrogen has an oxidation number of -1 is LiH (lithium hydride).
18-The oxidation number of chlorine in ClO₄⁻ (perchlorate ion) is calculated as follows:
x+4(−2)=−1
Solving for x we get x=+7.
19-In the reaction
S8 to H2S
the oxidation number of sulfur changes from 0 to -2.
20-In peroxide compounds, oxygen has an oxidation number of -1. An example is H₂O₂ (hydrogen peroxide).
Quiz 3 on Oxidation Numbers – Part 3
Multiple Choice:
1-What is the oxidation number of chromium in CrO₄²⁻ (chromate ion)?
a) +2
b) +3
c) +4
d) +6
2-In the compound NaNO₃ (sodium nitrate), the oxidation number of nitrogen is:
a) -1
b) +1
c) +2
d) +3
3-What is the oxidation number of carbon in CH₄ (methane)?
a) -1
b) +1
c) 0
d) -4
4-The oxidation number of phosphorus in PF₆⁻ (hexafluorophosphate ion) is:
a) -1
b) +1
c) +3
d) +5
5-What is the oxidation number of hydrogen in LiH₂ (lithium hydride)?
a) +1
b) -1
c) +2
d) -2
True/False:
6-In a redox reaction, the reducing agent gains electrons.
7-The oxidation number of oxygen in peroxides is -1.
8-Polyatomic ions can have variable oxidation numbers for different elements within the ion.
9-The sum of oxidation numbers in a molecule must be zero for it to be neutral.
10-The oxidation number of sulfur in SO₄²⁻ is +4.
Fill in the Blank:
11-The oxidation number of fluorine in compounds is always ____________.
12-Alkali Earth Metals (Group 2A) typically have an oxidation number of ____________.
13-In HClO₄ (perchloric acid), the oxidation number of chlorine is ____________.
14-The oxidation number of nitrogen in NH₄⁺ (ammonium ion) is ____________.
15-The oxidation number of manganese in MnO₄⁻ (permanganate ion) is ____________.
Short Answer:
16-Explain the significance of oxidation numbers in ionic compounds and covalent compounds.
17-Provide an example of a redox reaction and identify the oxidizing and reducing agents.
18-Calculate the oxidation number of sulfur in H₂SO₄ (sulfuric acid).
19-Describe the change in oxidation number of nitrogen in the reaction NO₂ to N₂O₄.
20-What is the oxidation number of chlorine in Cl₂ (elemental chlorine)?
The answers
C Here are the answers to the third quiz:
Multiple Choice:
1-Answer: c) +4
2-Answer: d) +3
3-Answer: c) 0
4-Answer: a) -1
5-Answer: c) +2
True/False:
6-Answer: True
7-Answer: True
8-Answer: True
9-Answer: True
10-Answer: False (The oxidation number of sulfur in SO₄²⁻ is +6)
Fill in the Blank:
11-The oxidation number of fluorine in compounds is always -1.
12-Alkali Earth Metals (Group 2A) typically have an oxidation number of +2.
13-In HClO₄ (perchloric acid), the oxidation number of chlorine is +7.
14-The oxidation number of nitrogen in NH₄⁺ (ammonium ion) is -3.
15-The oxidation number of manganese in MnO₄⁻ (permanganate ion) is +7.
Short Answer:
16-In ionic compounds, oxidation numbers indicate the charge of ions formed by atoms, whereas in covalent compounds, they represent the electronic shift in the chemical bond between atoms.
17-An example of a redox reaction is the following:
Zn+CuSO4→ZnSO4+Cu
The reducing agent is zinc (Zn), and the oxidizing agent is copper (Cu).
18-The oxidation number of sulfur in H₂SO₄ (sulfuric acid) is calculated as follows:
2(+1)+x+4(−2)=0
Solving for x, we get x=+6.
19-In the reaction NO2 to N2O4 , the oxidation number of nitrogen changes from +4 to +3.
20-The oxidation number of chlorine in Cl₂ (elemental chlorine) is 0.