Will give 10 pts if u can help me, please help me?

Question

The question i have to solve is this:

A student prepares a solution by dissolving 4.08 g of NaOH in enough water to make 300. mL of solution.
The student then transfers 34.0 mL of this solution into a 100. mL volumetric flask. Water is then added
up to the 100. mL mark.
What is the final molarity of NaOH in the 100. mL flask ?

okay, so what i did is i calculated the moles in the first solution by dividing the molar mas of NaOH by 4.08 grams (given), then i multiply this by .3 Liters, which gives me a molarity of .0306, then i multiplied this by 34 and divided by a 100 giving me .1. This however is the incorrect answer, can someone please help me. What am i doing wrong?

NO MORE ANSWERS NECESSARY, THANK YOU

Answer 1

It's best to keep track of the units.

? moles NaOH = [(4.08g NaOH)] x
[(1mol NaOH)/(40g NaOH)] = 0.102 mol NaOH

note how the units cancel

now calculate molarity
Molarity = [(#moles)/(#liters soln)]

M = [(0.102 mol NaOH)/(0.3L soln)= 0.34M

Now determine the moles in 34ml

? moles = (34.0 ml)x
[(0.34 moles)/(1000 ml) = 0.01156 moles

now determine the molarity of the smaller flask
M= [(0.01156moles)/(0.1 L) = 0.1156 M NaOH

Answer 2

I'm not sure if this is correct, but try to solve the problem using grams and then change your final answer to moles. It is much easier.

4.08gm in 300ml = 0.4624gm in 34ml
0.4624gm in 34ml = 1.36gm in 100ml

molar mass of NaOH = 23+16+1= 40
1 mole of NaOH = 40gm
x mole of NaOH = 1.36gm
x= 1.36/40
x= 0.034 mole

Answer 3

I think your calculation of molarity is wrong:

molarity = moles / liter

# mole = grams / molecular weight

Step 1:
4.08 gm of NaOH / 40gm/mole = 0.102 moles

Step 2:
0.102 moles / 0.3 L = 0.34 M solution

Step 3:
0.34 * 0.034 L / 0.1 L = 0.1156 M solution
( or 0.12 M if rounded to 2 significant figures)

Answer 4

asdf

Answer 5

ijgsavc