[sarah1004]

Standardization of NaOH solution:
a)volume of 6.0M NaOH solution used: 20mL
b)approximate[NaOH] after dilution to 400mL: 0.5M
c)weight of empty flask: 86.525g
d)weight of flask plus KHP: 87.253g
e)weight of KHP: 0.728g
f)moles of KHP: 0.00356mol
g)moles of NaOH: same answer as moles of KHP
h)initial buret reading: 0mL
I)final buret reading: 13mL
j)volume of NaOH used up:____mL
k)[NaOH]:_____M

I got this data.
And My questions are j),and k).
I don't know how to find volume of NaOH used up and [NaOH]

Please help me and please show me how to do this

Thanks

[Perito]

a. You used 20 mL of 6.0 M solution. 6.0 M is 6 moles/liter. You used 20 mL (0.020 L), you used 0.02 x 6 = 0.12 moles of NaOH.

b. should be self-explanatory

c, d, e, and f are used to figure out how much KHP you used. You calculated 0.00356 moles. I won't check your arithmetic.

g. The Moles of NaOH equal the moles of KHP because the reaction is



h, i, and j are used to determine how much NaOH solution you used. I'm not sure you read your buret carefully enough because it's very unusual to start exactly at zero and even less usual to finish exactly at 13.0 mL. Once you determine the volume of NaOH you used (13.0 - 0.0 = 13), you can calculate the exact molarity of NaOH because

a) you know the number of moles of KHP you used.
b) you know that 1 mole of KHP reacts with 1 mole of NaOH
c) Calculation:

concentration of NaOH = moles used / liters of solution.

[sarah1004]

Ohhh.. sorry
I got 11mL on (I)

[Unknown008]

j) Volume used = final burette reading - initial burette reading

k) You know the number of moles in the volume you got in j). Find the number of moles you expect to have in 1000 mL, proportions, or use your formula. If you use the latter, be sure to check your units well and not do the same mistakes as last time, OK?