[k3107q]

Calculate the molarities of the major ionic species present in 0.150 L of solution containing 27.6 g of sodium chloride.
   Correct.
    
Sodium ion concentration?

     3.145      M

   Correct.
    
Chloride ion concentration?

     3.145      M


Calculate the new molarities if 50.00 mL of the previous solution is diluted to 450. mL of new solution?

*****And I got stuck at this point

Sodium ion concentration?
...M

Chloride ion concentration?
..M

[rabolisk]

What does it mean to dilute a solution?

[k3107q]

i dont really know too , I copy whole question from my assignment to you guy for helping

[Fluorine]

Diluted means made less concentrated. You've added more (let's say water) to the solution and changed the molarity. However it's first asking you to take 50mL from the first solution then dilute it to 450.mL.

How many moles of each in 50mL of your first solution?
What would the molarity be if this many moles was in a total solution of 450.mL?

[opti384]

Keep in mind that when you usually dilute a solution, there will be a change only in the volume but not in the amount of solute.

[k3107q]

I'm not sure the results , any one got the result ? please show me ,Thanks
+and I got :

n(of 50 ml ) = 50/22.4 = 1/448 moles

=> M = (1/448)/(450/1000) = 5/1008 (M)

Is it correct or wrong ? please help me out

[sjb]

I'm not sure the results , any one got the result ? please show me ,Thanks
+and I got :

n(of 50 ml ) = 50/22.4 = 1/448 moles

=> M = (1/448)/(450/1000) = 5/1008 (M)

Is it correct or wrong ? please help me out

Not quite. Where have you got the figure of 22.4 from?

[k3107q]

that is another way to find moles , but i'm not sure ,so do u have another solution ?

[sjb]

I think the 22.4L is probably related to gases. How did you calculate the correct value of 3.145 M for the sodium ion concentration?

[Fluorine]

n(of 50 ml ) = 50/22.4 = 1/448 moles

Isn't molarity defined as; M = mol/V (liters)
To find moles couldn't you rearrange this to; MV = mol

Try again. If you know the solution starting is 3.145M concentration, you take 50mL, how many moles does this contain?

[k3107q]

i got the correct answer following this solution :

C1V1=C2V2
(3.145)(50/1000)=C2(450/1000)
C2 = 0.349 and that's it