Chemistry redox reaction - gases mixing

[Feodalherren]

Homework Statement

How many milliliters of Cl2 gas, measured at 28.0 °C and 750 torr, are needed to react with 18.5 mL of 0.173 M NaI if the I- is oxidized to IO3- and the Cl2 is reduced to Cl-?

Homework Equations

The Attempt at a Solution

So the molar mass is .0030906 mol NaI. Now I need to find out how many moles of Cl2 are needed to react completely with that.
So I need the balanced chemical equation.

Cl2 + NaI --> IO3- + Cl-

Redox:

2e- + Cl2 --> 2Cl-

NaI --> IO3- + Na+

This is where I get stuck.
I can't balance NaI as a redox reaction because I don't know the charges on that side. How do I balance the second part of the reaction?

 

[Feodalherren]

Is 3Cl2 + NaI + 3H2O --> IO3- + Na+ + 6H+ + 6Cl-

the correct balanced reaction?

 

[Borek]

Is 3Cl2 + NaI + 3H2O --> IO3- + Na+ + 6H+ + 6Cl-

the correct balanced reaction?

Technically - yes. But why don't you treat NaI as a dissociated salt (Na⁺+I^-), it is dissolved, isn't it?

 

[Feodalherren]

Ahh that's what was confusing me. I got the rest of it, thanks.

 

[nickH]

?

Ahh that's what was confusing me. I got the rest of it, thanks.

what was the solution, I am stumped

 

[Feodalherren]

So after you have the Redox reaction you have your ratio which is that for every 1 mol of NaI you have 3 moles of Cl2.

You know that you have 18.5 mL of 0.173 M NaI so therefore

.0185 L (.173 mol NaI/L) = moles of NaI.

Now multiply that by three to get the moles of Cl2 because as shown from the balanced chemical equation - you need 3 moles of Cl2 for every 1 mol of NaI.

From there you have

PV=nRT

Make sure to convert P to atm and T to Kelvin. n Is the amount of moles of Cl2 - solve for V. Done.

Edit: oh yeah - convert to mL since that's what the question was asking for.