write the steps required to prepare 250mL mL of an aqueous solution of copper (II) sulfate pentahydrate that has a concentration of 1.00 M

Answer 1

Hello Samantha,

Try rephrasing the question to clarify the ask: I need to know how much solute is needed to dissolve in 250 ml water so that the solution is 1 Molar.

now ask yourself: what law do I use? the answer would be molarity = # moles of solute/ liters of solution

so a 1 M = 1 mole copper || sulfate pentahydrate / 1 liter of solution.

since in lab we either use volume or gm and not moles we need to convert moles to gm

copper || sulfate pentahydrate : CuSO₄ 5H₂O

now we need to figure out the molecular weight of this compound.

M.W(CuSO₄ 5H₂O) = atomic weight (Cu) + atomic weight (S) + 4*atomic weight (O) +

5*atomic weight (Water)

Use your periodic table to get the atomic weights of these elements and plug them in the formula

M.W(CuSO₄ 5H₂O) = 63.5 + 32 + 4*16 + 5 (2*1 + 16)

now in a test if your are given a calculator use it, if not then round the numbers to make calculations easier.

M.W(CuSO₄ 5H₂O) = 249.5 gm

now this amount in 1 Liter solution makes 1 Molar

how much do I need to dissolve in 250 ml ?

1 M = 249.5 / 1 Liter = gm of solute / 0.250

gm of solute = 0.250 * 249.5 = 62.375

now we just need to write the steps:

1- Weigh an empty graduated beaker and write down weight P_w

2- In a notebook calculate the total weight = 62.375 + P_w

3- Keep beaker on balance and add the solute till the balance reads the total weight calculated in step 2

4- Add water to the beaker carefully till the mark that reads 250 ml.

Ta Daa :) we have our target solution, a 250 ml of 1 M copper || sulfate pentahydrate

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Answer 2

Copper(II) sulfate pentahydrate = CuSO₄•5H₂O MW = 249.69

250 ml x 1L/1000 ml = 0.250 L

1.00 M = 1.00 moles/liter

1.00 mol/L x 0.250 L x 249.69 g/mol = 62.42 g = 62 grams

Weigh out 62 grams of copper(II) sulfate pentahydrate

Place the sample in a 250 ml volumetric flask

Add d.H₂O to a final volume of 250 ml.