Question

1) what volume of a 1.25 M solution of HCl is needed to make a 2.00L solution that is 0.05000M HCL?

2) concider the oxidation reduction reaction where zinc metal reacts with an aqueous solution of copper (II) chloride to produce copper meal and zinc II chloride.

a)write balanced equation for reation and lable oxidation numbers of copper and zinc on both sdes of the reaction:

b) which species os the reducing agent (being oxidized)?

c) how many electrons are bing transferred in the reaction?

d) what are the 1/2 reactions?

Ox 1/2 rxn?

Red 1/2 rxn:

Answer 1

(1) Here we have to use M1V1=M2V2

Given M1=1.25 M, V1=?,

M2=0.05 M and V2=2 L.

Therefore V1=M2V2/M1=(0.5 M x 2 L)/(1.25 M)=0.8 L.

The volume required=0.8 L or 800 mL.

(2)(a)

The balanced reaction is

Zn(s) + CuCl2(aq) ------> ZnCl2(aq) + Cu(s)

0 . +2. +2 . 0

The oxidation numbers are mentioned here.

(b) Here Zinc is oxidised then it act as reducing agent.

And Copper is reduced then it act as oxidising agent.

(c) Number of electons transferred=2 e^-

(d) The half reactions are shown below

Oxidation half rxn: Zn(s) --------> Zn^+2(aq) + 2 e^-

Reduction half rxn: Cu^+2(aq) + 2e^- --------> Cu(s)

Overall rxn: Zn(s) + Cu^+2(aq) ----------> Zn^+2(aq) + Cu(s)

Therefore here 2 electons transferred.

Please let me know if you have any doubt. Thanks