Identify the redox reactions below and identity the species being oxidized and r

Question

Identify the redox reactions below and identity the species being oxidized and reduced in those reactions. If it is not a redox reaction, write "NA" next to the reaction. a) CaCO_3(s) + 2HCl(aq) rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g) b) 2Al(s) + 3Cl_2(g) rightarrow 2 AlCl_3(s) Cu(s) + 2 AgNO_3(aq) rightarrow Cu (NO_3)_2 (aq) + 2 Ag(s) Calorimetry and Hess' Law Briefly describe the main concept of Hess's Law and how it relates to state functions. Student A performed the experiment using calorimetery to verify Hess's law for the three law reactions below: Rxn A: HCl(aq) +NaOH (aq) rightarrow H_2O(I) + NaCl(aq) delta H = -11686.38 cal/mol Rxn B:H_2O(I) + NaOH (s) rightarrow NaOH (aq) delta H = -7105.98 cal/mol 8Rxn C: HCl(aq) + NaOH(s) rightarrow H_2O(I) + NaCl(aq) delta H = -18395.33 cal/mol Calculate the % error in Student A's experiment.

Explanation / Answer

(2)

Oxidation: It is a procee that involved loss of electorns

Reduction: It is process that involved gain of electrons.

Oxidising agent: The species that oxidises other species (OR) The species that undergoes reduction.

Reducing agent: The species that reduces other species (OR) The species that undergoes oxidation.

**** TO identify whether a particle undergoes oxidation or reduction in a reaction, observe the oxdation of state of that species in both reactants side and products side.

If the oxidation state is increased while moving from left to right the species is said to undergo oxidation.

If the oxidation state is decreased while moving from left to rigth the species is said to undergo reduction.

(a)

CaCO3 (s) + 2 HCl (aq.) --------> CaCl2 (aq.) + H2O (l) + CO2 (g)                       NA

      Left   Right

Ca   +2    +2

O      -2     -2

H     +1    +1

Cl    -1      -1

C     +4    +4

Since there is no change in the oxidation state of any atoms while moving from left to right, the reaction is not a redox reaction.

(b)

2 Al (s) + 3 Cl2 (g) -------------> 2 AlCl3 (s)

Atom Left Right

Al       0    +3

Cl      0     -1

Since the oxidation of Al is increased from 0 to +3, it undergoes oxidation and the oxdation state of Cl is decreased from 0 to -1, it underoges reduction.

So, oxidisng agent is Cl2 and reducing agent is Al

(c)

Cu (s) + 2 Ag(NO3)2 (aq.) ------------> Cu(NO3)2 (aq.) + 2 Ag (s)

Atom Left Right

Cu     0      +2

Ag    +1      0

N     +5      +5

O     -2       -2

Since the oxidation state of Cu is increased from o t0 +2, it is said to undergo oxidation and the oxidation state of Ag is decreased from +1 to 0, it is said to undergo reduction.

So, oxidising agent is Ag+ and Reducing agent is Cu

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---