Concentration after combining two solutions? Help me disprove my teacher!?

Question

If one were to combine 100 mL of 0.3 Molar BaCl2 solution and 150 mL of 0.4 Molar NaCl solution, what would the final molar concentration of chloride ions be in the resulting solution?

This was a problem on a chemistry test that I recently took. I am convinced the answer is 0.2 M, although my chemistry teacher tells me that it is 0.48 M. What do you think?

Answer 1

Well, chloride is known to be a problem as it can volatolize during the analysis. So, I suppose if the analytical chemist were sloppy he/she could end up with a result less than what was started with.... Other than that
100 mL of 0.3 molar Cl(-)2 is 100 ml of 0.6 molar Cl(-)
150 mL of 0.4 molar Cl is 150 mL of 0.4 molar
or 100 mL with 0.06 moles in it of Cl(-) and 150 mL with 0.6 moles of Cl(-) for a total of 250 mL and .12 moles or .48 moles per 1000 ml. Your idea that the final concentration is going to be outside the range of two concentrations you started with is faulty... Similarly the two Ba concentrations are 0 and 0.3 and for Na 0 and .4 so their final concentrations will be in those ranges --- were you to get an answer of .4 for Ba or .7 for the Na you would KNOW it is wrong without doing any math. The Cl(-) concentations start at .6 and .4 so after mixing its gotta be in that range, see?

Answer 2

[Cl-] = (100 x 2 x 0.3 + 150 x 0.4) / 250 = 0.48 M

Sorry bud, looks like the old bloke is right

Answer 3

The teacher is right:
concentration = number of moles / volume
number of moles = concentration x volume

Number of moles of Cl- in BaCl2:
n = 0.3 x 2 (as CL2) x 0.1
n = 0.06 mol

Number of moles of Cl- in NaCl:
n = 0.4 x 1 x 0.15
n = 0.06 moles

Whole solution:
c = n / v
c = (0.06 + 0.06) / (0.1+ 0.15)
c = 0.48 mol dm^-3

Answer 4

The principle is (vm)1+(vm)2= VM
Inputs: v1=0.1
v2= 0.15
V= 0.25
m1=0.6 note each mole of salt provides 2 moles of "chloride"
m2=0.4
And (0.1x0.6)+(0.15x0.4)=(0.25M)
0.12 moles= 0.25 M
M= 0.48 molar
The teacher is right, but don't let it phase you.

Answer 5

for the BaCl2 solution you have
0.3x2moles per litre of Cl ions (the stochiometry hac Cl2) = 0.6 moles per litre.
You have 100 mL = 100/1000 * 0.6 moles per 100 mL = 0.06 moles of cl ions

for the NaCl solution you have
0.4x1 moles per litre Cl ions = 0.4 moles per litre
you have 150ml = 150/1000 * 0.4 moles per 150 mL = 0.06 moles Cl ions

In the combined solution you have
0.06 + 0.06 = 0.12 moles of Cl ions
volume = 250 mL

Concentration = 0.12 moles/250 mL = (1000/250)*0.12 moles per litre = 0.48 moles per litre!

Sorry... :)

Answer 6

No 2 state answer. in straight forward terms Palestine. no compromise for peace! They shouldn't sacrifice something for the sake of peace! i understand this makes me sound like a warmonger. yet a answer one might say that Palestinians provide up each thing and pass to refugee camps in Lebanon or someplace else. that would restoration peace does no longer it? yet what approximately justice?