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IB Chemistry: Electron transfer reactions — Practice Questions & Answers

Q: In terms of electrons, oxidation is defined as the:

Loss of electrons. Using OIL RIG, Oxidation Is Loss of electrons; reduction is gain of electrons.

Q: What is the oxidation state of oxygen in water, $\text{H}_{2}\text{O}$?

$-2$. Oxygen is normally $-2$ in its compounds (except peroxides and with fluorine), so in $\text{H}_{2}\text{O}$ it is $-2$.

Q: What is the oxidation state of manganese in the permanganate ion, $\text{MnO}_{4}^{-}$?

$+7$. Each O is $-2$ ($4 \times -2 = -8$); the overall charge is $-1$, so Mn $= -1 - (-8) = +7$.

Q: During a redox reaction, the oxidising agent is the species that:

Is reduced and gains electrons. The oxidising agent oxidises something else and is itself reduced, gaining electrons.

Q: In a voltaic (galvanic) cell, oxidation takes place at the:

Anode. In any electrochemical cell oxidation occurs at the anode; in a voltaic cell the anode is the negative electrode.

Q: Which is the correctly balanced half-equation for the reduction of $\text{Fe}^{3+}$ to $\text{Fe}^{2+}$?

$\text{Fe}^{3+} + e^{-} \rightarrow \text{Fe}^{2+}$. Reduction is gain of electrons; $\text{Fe}^{3+}$ gains one electron to become $\text{Fe}^{2+}$: $\text{Fe}^{3+} + e^{-} \rightarrow \text{Fe}^{2+}$.

Q: In terms of electrons, reduction is the _____ of electrons.

gain / gaining. Reduction Is Gain of electrons (RIG).

Q: The oxidation state of sulfur in the sulfate ion, $\text{SO}_{4}^{2-}$, is $+_____$.

6 / six. Each O is $-2$ ($-8$ total); overall charge $-2$, so S $= -2 - (-8) = +6$.

Q: What is the oxidation state of silver in the compound Ag2S (where S is -2)?

+1. Two Ag must total +2 to balance S at -2, so each Ag is +1.

Q: In terms of electrons, oxidation is defined as

the loss of electrons. Oxidation is the loss of electrons (OIL: oxidation is loss).

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Practice questions with answers

1 Multiple choice · Easy

In terms of electrons, oxidation is defined as the:

Loss of electrons
Gain of electrons
Loss of protons
Gain of neutrons

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2 Multiple choice · Easy

What is the oxidation state of oxygen in water, $\text{H}_{2}\text{O}$?

$-2$
$+2$
$-1$
$0$

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3 Multiple choice · Medium

What is the oxidation state of manganese in the permanganate ion, $\text{MnO}_{4}^{-}$?

$+7$
$+2$
$+4$
$-7$

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4 Multiple choice · Medium

During a redox reaction, the oxidising agent is the species that:

Is reduced and gains electrons
Is oxidised and loses electrons
Loses protons
Does not change

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5 Multiple choice · Medium

In a voltaic (galvanic) cell, oxidation takes place at the:

Anode
Cathode
Salt bridge
Voltmeter

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6 Multiple choice · Hard

Which is the correctly balanced half-equation for the reduction of $\text{Fe}^{3+}$ to $\text{Fe}^{2+}$?

$\text{Fe}^{3+} + e^{-} \rightarrow \text{Fe}^{2+}$
$\text{Fe}^{3+} \rightarrow \text{Fe}^{2+} + e^{-}$
$\text{Fe}^{2+} + e^{-} \rightarrow \text{Fe}^{3+}$
$\text{Fe}^{3+} + 3e^{-} \rightarrow \text{Fe}^{2+}$

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7 Fill in the blank · Easy

In terms of electrons, reduction is the of electrons.

8 Fill in the blank · Medium

The oxidation state of sulfur in the sulfate ion, $\text{SO}_{4}^{2-}$, is $+$.

9 Multiple choice · Medium

What is the oxidation state of silver in the compound Ag2S (where S is -2)?

+1
+2
-2
0

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10 Multiple choice · Easy

In terms of electrons, oxidation is defined as

the loss of electrons
the gain of electrons
the gain of protons
the loss of neutrons

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IB Chemistry: Electron transfer reactions — Practice Questions & Answers

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