What Steps Solve a Complex Molarity Problem?

[pasido]

Homework Statement

http://i.imgur.com/Rz0qB.png

Homework Equations

The answer is B, but I would like to know how to find the answer.
Molarity = moles * volume

The Attempt at a Solution

Yep, I tried for 15+ minutes and couldn't get the darn units to cancel out. A worked out solution would be very helpful.

 

[sjb-2812]

Homework Statement

http://i.imgur.com/Rz0qB.png

Homework Equations

The answer is B, but I would like to know how to find the answer.
Molarity = moles * volume

The Attempt at a Solution

Yep, I tried for 15+ minutes and couldn't get the darn units to cancel out. A worked out solution would be very helpful.

Is there a reason you have provided an image, rather than text?

How many moles of Na+ do you need?

 

[symbolipoint]

The relevant equation, "Molarity = moles * volume", is wrong.

 

[ARlTHMOMANIA]

Molarity = mole per liter or mol/L

Determine the ratio of Na+ in Na3PO4 by observing the formulas (*Hint 1/3 or 3/1). Multiply this by your Molar concentration of Na+ given in the problem.

Next, set up a ratio of:

[Na*(1/3 or 3/1) (M)] / Na3PO4 (M)

or

Na3PO4 (M) / [Na*(1/3 or 3/1) (M)]

(reason whether the answer should be greater than 1 or less than 1 to determine which ratio to use).

Finally multiply this by the volume you're trying to prepare.

 

[DeeNos]

I can provide you with a solution to this complex molarity problem. First, let's define some terms and equations that will help us solve this problem. Molarity is defined as the number of moles of solute per liter of solution. This can be expressed mathematically as M = moles of solute / liters of solution. We also know that moles can be calculated by multiplying the given mass of the solute by its molar mass. Therefore, we can rewrite the equation as M = (mass of solute * molar mass) / liters of solution.

Now, let's apply this to the problem at hand. We are given a solution with a volume of 250 mL (0.25 L) and a concentration of 0.05 M. We also know that the solute is Fe(NO3)3 and its molar mass is 241.86 g/mol. Let's plug these values into our equation:

M = (mass of solute * molar mass) / liters of solution
0.05 M = (mass of Fe(NO3)3 * 241.86 g/mol) / 0.25 L

We can rearrange this equation to solve for the mass of Fe(NO3)3:
mass of Fe(NO3)3 = (0.05 M * 0.25 L * 241.86 g/mol) / 1 M
mass of Fe(NO3)3 = 3.0225 g

Therefore, the answer is B, 3.0225 g of Fe(NO3)3. I hope this solution was helpful in understanding how to solve complex molarity problems.