[phoenixrising]

Question 1
a) What weight of EDTA powder is required to prepare a 0.5 M solution of EDTA (500 mL) in water?
b) What would the concentration be in mM?

For a, I did a cross multiply method:

__x__ g EDTA  0.5 M solution of EDTA
292.24 g EDTA 1 M of EDTA

(1 mol)(x) = (0.5 mol)(292.24 g/mol)
x = 146.12 g/mol of EDTA

For b:

146.12 g EDTA x (1 mol / 292.24 g) 0.5 M
0.5 M x (1000 mM / 1 M)500 mM = 500 mM

Are those right?

My question: what do I do with the 500 mL (in the question above for part A)? Do I convert the 146 g of EDTA to mL??? Please *delete me*

[phoenixrising]

Question 3
b. How much sodium acetate powder is required to prepare a 3M (200 mL) aqueous solution?

___x___ g C₂H₂NaO₂ 3 mol C₂H₂NaO₂
82.0343 g C₂H₂NaO₂ 1 mol C₂H₂NaO₂

(1 mol)(x) = (3 mol)(82.0343 g / mol)
x = 246 g of C₂H₂NaO₂ is required.


Do I convert 246 g of C₂H₂NaO₂ to mL now, given 200 mL aqueous solution?


c. The lab doesn't have anhydrous sodium acetate in stock, but rather sodium acetate trihydrate. How much of the hydrate form would be required to prepare an equivalent solution?

I don't know how to do this one!
All I have writen down is:

C₂H₂NaO₂ x 3 H₂O and they want hydrate in g/mol as the product?

[sjb]

For both, you don't seem to have taken into account the volume of the solution. What does 3M mean? For 3 perhaps check your formula for sodium acetate too.