During a class experiment, students were required to dilute 50.0 mL of 2.50 M Na2SO4 by mixing it with 50.0 mL of distilled water. One of the groups accidentally mixed the 2.50 M Na2SO4 solution with 50.0 mL of 0.0500 M Na2SO4 instead of distilled water. What is the molarity of the resulting solution that this group made?
A. 1.25 M
B. 1.28 M
C. 2.45 M
D. 2.55 M

Question

During a class experiment, students were required to dilute 50.0 mL of 2.50 M Na2SO4 by mixing it with 50.0 mL of distilled water. One of the groups accidentally mixed the 2.50 M Na2SO4 solution with 50.0 mL of 0.0500 M Na2SO4 instead of distilled water. What is the molarity of the resulting solution that this group made?
A. 1.25 M
B. 1.28 M
C. 2.45 M
D. 2.55 M

australopithecus · Answer

Molarity = Moles/Litres

australopithecus · Answer

So what you need to do is figure out total moles,

find moles of Na2SO4 in 50mL=0.05L of 2.50M solution
find moles of Na2SO4 in 50mL=0.05L of 0.05M solution

Then simply add the moles from both solutions and then add the volume then calculate the new molarity

australopithecus · Answer

Using the formula I provided you with

anonymous · Answer

I'm trying to get the answer ... not work it out

australopithecus · Answer

Oh well go to yahoo answers, I'm not here to do your homework for you.

australopithecus · Answer

or you could save time and just work it out yourself because it is an easy question.

anonymous · Answer

its an easy question? maybe for you but not for me.  such an ignorant person you are. bye

australopithecus · Answer

You undersell yourself, I'm 100% certain you could solve this problem

australopithecus · Answer

Molarity = Moles/Litres
Molarity*Litres = Moles
Just plug values into these equations and you have your answer

australopithecus · Answer

You should not be so quick to insult someone who is trying to help you.

australopithecus · Answer

You could even show me your work and I dont mind tell you if you are on the right track.

mathmate · Answer

If you are  mixing two solutions of different concentrations, you need to calculate the total number of moles (C1V1+C2V2) and divide by the total volume (V1+V2).
Example,
Mix 30.0 mL of 0.200M H2SO4 with 25.0 mL of 0.100M H2SO4. Find final molarity.

#mol in 30 mL of 0.2M = 0.03 L *0.2 mol/L= 0.006 mol
#mol in 25 mL of 0.1M = 0.025 L * 0.1 mol/L = 0.0025 mol
Total #mol of H2SO4  = 0.005+0.0025 = 0.0075 mol
Total volume = 0.030+0.025 = 0.055 L
Final molarity  = (use @Australopihecus 's formula)
0.0075 mol / 0.055 L = 0.136 mol/L = 0.136M

REMEMBER: This is an example to help you, this is NOT the answer.
Go ahead to work on your problem so that you can solve a similar problem later on.