A student determines the cobalt(II) content of a solution by first precipitating it as cobalt(II) hydroxide, and then decomposing the hydroxide to cobalt(II) oxide by heating. How many grams of cobalt(II) oxide should the student obtain if her solution contains 46.0 mL of 0.561 M cobalt(II) nitrate?
Co(NO3)2 ==> Co(OH)2 --> CoO
mols Co(NO3)2 = M x L = ?
mols CoO = mols Co(OH)2 = mols Co(NO3)2
grams CoO = mols x molar masss
how many grams is that?
sorry i am stuck on many questions that's why used diff names. i need help and be grateful if u can help but most questions I don't know how to work it out.
What is confusing about this? And I suggest you pick any name and stick to it. It helps us help you if you do that.
For this problem all you need is two steps. M x L = mols and mol x molar mass = grams.
i don't know much about chemitry that's why its confusing
I don't know how to calculate them
Step 1. Pick out M x L. That's in the problem. M is 0.561; L is 0.046 L.
M x L = ? you can do on your calculator.
Step 2. grams = mols x molar mass
You have mols from the calculator. Multiply that by the molar mass of CoO. You can calculate that from the periodic table. Co = about 58.93 and O is 16 so 58.93 + 16 = ?
To find the mass of cobalt(II) oxide obtained, we first need to calculate the number of moles of cobalt(II) nitrate in the given solution. Then, using the stoichiometry of the reaction, we can determine the number of moles of cobalt(II) oxide formed. Finally, we can use the molar mass of cobalt(II) oxide to convert the moles to grams.
Step 1: Calculate the number of moles of cobalt(II) nitrate
Given:
Volume of the cobalt(II) nitrate solution = 46.0 mL
Concentration of the cobalt(II) nitrate solution = 0.561 M
To calculate the moles, we'll use the formula:
Moles = Concentration × Volume (in liters)
Converting the volume from milliliters to liters:
Volume = 46.0 mL ÷ 1000 mL/L = 0.046 L
Moles of cobalt(II) nitrate = 0.561 M × 0.046 L = 0.0258 moles
Step 2: Determine the moles of cobalt(II) oxide
The balanced chemical equation for the reaction is:
Co(NO3)2 + 2NaOH → Co(OH)2 + 2NaNO3
From the equation, we can see that 1 mole of cobalt(II) nitrate (Co(NO3)2) reacts with 1 mole of cobalt(II) hydroxide (Co(OH)2).
Therefore, the number of moles of cobalt(II) oxide (CoO) formed will also be 0.0258 moles.
Step 3: Convert moles of cobalt(II) oxide to grams
The molar mass of cobalt(II) oxide (CoO) is 74.93 g/mol.
Mass = Moles × Molar mass
Mass = 0.0258 moles × 74.93 g/mol ≈ 1.92 grams
Therefore, the student should obtain approximately 1.92 grams of cobalt(II) oxide from the solution.