Question

PLEASE PLEASE HELP ME

A student takes 2.00 mL of a 1.30 x 10-3M stock solution of copper sulfate (CuSO4) and combines it with enough water to make 100.0 mL of a new solution, called “Solution A”.
i) Calculate the molarity of Solution A

Answer 1

What remains constant here is the number of moles of solute. So the number of moles before and after dilution should be the same. And to obtain the number of moles you multiply the molarity with the volume. Does this help?

Answer 2

How do I set up the problem to solve it ?

Answer 3

Do I have to calculate the moles in the 2 mL first and then solve for those moles in the 100 ml solution ?

Answer 4

?

Answer 5

M = moles/Liters

Answer 6

where,

M = molarity

Answer 7

you should be able to solve it now

Answer 8

So 1.30 X10-3 is molarity ?

Answer 9

do you understand what concentration is?

Answer 10

1.30 x 10^(-3)M = 1.30 x 10^(-3)moles/Liter

so you have 1.30 x 10-3moles per 1 liter

Answer 11

you are increasing the amount of solvent in your solution though so your concentration should change

Answer 12

you should have a lower concentration

Answer 13

Okay so I calculated the moles of the first solution
but how do I use the first solution to get the molarity of solution A

Answer 14

2.6 X10-6 moles in the 2ml solution

Answer 15

Any questions?

Alternatively you can just multiply apply

C1V1 = C2V2

Answer 16

Ugh I'm out of it right now sorry

Answer 17

They just increased the volume of the solution to 100mL

so,

1.30 x 10-3M*(2mL/100mL)

Answer 18

No its okay I am just confused

Answer 19

So molarity is 2.6x10-6

Answer 20

https://www.wolframalpha.com/input/?i=+1.30*10^-3M*%282mL%2F100mL%29

Answer 21

Thank you ! I think thats right because I double checked different ways and it keeps coming out the same

Answer 22

just use C1V1 = C2V2

Answer 23

ugh I'm so out of it today

Answer 24

No worries thank you