1. From the following ionic equations below, put a tick (✓) if there is a reaction taking place and a cross (X) if there is no reaction taking place.
a. [tex]Zn ^{2+}( aq )+ Fe ( s ) \longrightarrow Fe ^{2+}(\frac{ aq }{ a })+ Zn ( s )[/tex]
b. [tex]Mg ^{2+}( aq )+ Zn ( s ) \longrightarrow Zn ^{2+}( aq )+ Mg ( s )[/tex]
c. [tex]Fe ^{2+}( aq )+ Zn ( s ) \longrightarrow Zn ^{2+}( aq )+ Fe ( s )[/tex]
d. [tex]Pn ^{2+}( aq )+ Cu ( s ) \longrightarrow Cu ^{2+}( aqu ) ! Pu ( s )[/tex]
e. [tex]Cu ^{2+}( aq )+ Fe ( s ) \longrightarrow Fe ^{2+}( aq )+ Cu ( s )[/tex]
2. Define spectator ion
Answer (2)
Determine if a reaction occurs based on the reactivity series of metals.
Compare the reactivity of the solid metal to the metal ion in solution; a reaction occurs if the solid metal is more reactive.
Reactions occur in equations 1, 3, and 5; no reactions occur in equations 2 and 4.
Define a spectator ion as an ion present in the same form on both sides of the equation and does not participate in the reaction. The reactions that take place are 1, 3, and 5. The reactions that do not take place are 2, and 4. Spectator ion is an ion that does not participate in the reaction and is present in the same form on both sides of the equation. R e a c t i o n s : 1 , 3 , 5 ; N o R e a c t i o n s : 2 , 4 ; Sp ec t a t or I o n : I o n t ha t d oes n o tp a r t i c i p a t e in t h ere a c t i o n .
Explanation
Problem Analysis We are given five ionic equations and asked to determine if a reaction takes place in each case. We also need to define a spectator ion. To determine if a reaction occurs, we need to compare the reactivity of the metal in its solid form to the metal ion in solution. A reaction will occur if the solid metal is more reactive than the metal ion.
Reactivity Series The reactivity series of metals is as follows (from most to least reactive): Li, K, Ba, Sr, Ca, Na, Mg, Al, Mn, Zn, Cr, Fe, Cd, Co, Ni, Sn, Pb, H, Cu, Hg, Ag, Pt, Au.
Equation 1
Z n 2 + ( a q ) + F e ( s ) ⟶ F e 2 + ( a q ) + Z n ( s ) . Iron (Fe) is more reactive than Zinc (Zn). According to the reactivity series, Fe is to the left of Zn, meaning it's more reactive. Therefore, the reaction will occur.
Equation 2
M g 2 + ( a q ) + Z n ( s ) ⟶ Z n 2 + ( a q ) + M g ( s ) . Zinc (Zn) is more reactive than Magnesium (Mg). According to the reactivity series, Zn is to the right of Mg, meaning it's less reactive. Therefore, the reaction will not occur.
Equation 3
F e 2 + ( a q ) + Z n ( s ) ⟶ Z n 2 + ( a q ) + F e ( s ) . Zinc (Zn) is more reactive than Iron (Fe). According to the reactivity series, Zn is to the left of Fe, meaning it's more reactive. Therefore, the reaction will occur.
Equation d
P b 2 + ( a q ) + C u ( s ) ⟶ C u 2 + ( a q ) + P b ( s ) . Copper (Cu) is more reactive than Lead (Pb). According to the reactivity series, Cu is to the right of Pb, meaning it's less reactive. Therefore, the reaction will not occur.
Equation e
C u 2 + ( a q ) + F e ( s ) ⟶ F e 2 + ( a q ) + C u ( s ) . Iron (Fe) is more reactive than Copper (Cu). According to the reactivity series, Fe is to the left of Cu, meaning it's more reactive. Therefore, the reaction will occur.
Spectator Ion Definition A spectator ion is an ion that exists in the same form on both the reactant and product sides of a chemical equation. These ions do not participate in the reaction and are not included in the net ionic equation.
Final Answer Based on the reactivity series, the reactions that take place are:
Z n 2 + ( a q ) + F e ( s ) ⟶ F e 2 + ( a q ) + Z n ( s ) - Reaction takes place.
M g 2 + ( a q ) + Z n ( s ) ⟶ Z n 2 + ( a q ) + M g ( s ) - No reaction takes place.
F e 2 + ( a q ) + Z n ( s ) ⟶ Z n 2 + ( a q ) + F e ( s ) - Reaction takes place.
P b 2 + ( a q ) + C u ( s ) ⟶ C u 2 + ( a q ) + P b ( s ) - No reaction takes place.
C u 2 + ( a q ) + F e ( s ) ⟶ F e 2 + ( a q ) + C u ( s ) - Reaction takes place.
A spectator ion is an ion that does not participate in the reaction and is present in the same form on both sides of the equation.
Examples
Understanding the reactivity series and predicting whether a reaction will occur is crucial in various real-world applications. For example, in designing corrosion-resistant materials, engineers need to know which metals will react with others in specific environments. Similarly, in electroplating, the reactivity series helps determine which metal will coat another metal. This knowledge is also essential in the extraction of metals from their ores, where more reactive metals are used to displace less reactive ones from their compounds. For instance, zinc is used to extract silver from silver cyanide solutions.
Reactions occur in equations 1, 3, and 5, while no reactions occur in equations 2 and 4. A spectator ion is an ion that remains unchanged during the reaction and is present in the same form on both sides of the equation.
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