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Preparing a solution of Cu(NO3)2 · 3H2O (solid) with NH3 30%

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Wollmy:
I have a question about the preparation of a solution. I have a solid Cu(NO3)2 · 3H2O and I want to make solutions with differente Concentration [M] (0,005; 0,010; 0,015 and 0,020) using NH3 30% (density 0,89) as a solvent.
My first though was to simply Multiply the desired Molar Concentration with the Volume of NH3 and the Molmass of the Cu(NO3)2 · 3H2O and so I would obtain the amount of solid I needed to weight. For example: to obtain a Molar Concentration of 0,010: 0,010 mol.L-1 × 0,020 L × 241,62 g.mol-1 and thus obtain the amount of 0,048324g needed to be weight to obtain a 0,010 M solution. For me this doesnt seem right.
My other though was to make a solution i.e. 0,05M of Cu(NO3)2 · 3H2O with water and a 1M solution of NH3 with water. The desired Molar concentrations I could achieve with dilution, right? If this is doable, im kinda lost and its kinda frustrating because im not seeing how hahahah.

So to summarize it:

- Can I work with the solid beeing dissolved directly in the Solvent and calculate the Concentration by just weighing the Mass of the Cu(NO3)2 · 3H2O and adding the Volume of NH3? (If yes, it would be great if you could show how to calculate it)

- Is it better to prepare 2 solutions. One solution dissolving Cu(NO3)2 · 3H2O in water and prepare i.e. 0,05M solution and prepare another solution of NH3 with water i.e. 1M and then mixture both to the disired concentration? (If yes, it would be great if you could show how to calculate it)


Many many thanks for any input

mjc123:
What's the molar concentration of a 30% ammonia solution?

Wollmy:

--- Quote from: mjc123 on September 01, 2021, 04:54:07 PM ---What's the molar concentration of a 30% ammonia solution?

--- End quote ---

On the bottle it doesnt give the information, it only says: Molar mass (M) 17,03 + aq g/mol. I found a table and also calculated it as 15,67 M
0,30(g NH3 / g aq. sol.) × 0,89(g aq. sol. / mL) × (1000 mL/L)/(17.03 g NH3/mol NH3) = 15,67 M (as NH3).

mjc123:
What does that say about the possibility of using 1M ammonia to prepare your solutions?

Wollmy:

--- Quote from: mjc123 on September 02, 2021, 06:16:37 AM ---What does that say about the possibility of using 1M ammonia to prepare your solutions?

--- End quote ---

Sorry, didnt understand your question. Is it if I could work with a 1M solution or how I would prepare the 1M Solution?

If its referring to dilute the probe, I did it by adding 3,189 mL of the NH3 30% in a 50mL Volumetric flask and adding Water until the 50 mL menisco.

As I mentioned, im kinda lost because im overlooking something or not seeing how to proceed in preparing my solutions

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