How many milliliters of 0.0850 M Na3PO4(aq) will react with 22.00 mL of 0.0800 M MgCl2(aq)?
3 MgCl2(aq) + 2 Na3PO4(aq) ==> Mg3(PO4)2(s) + 6 NaCl(aq)
V x M = V x M
(22.00mL)(0.0800M) = (0.0850M)(x)
Is this the correct set-up? Does it have 4 sigfigs, or am I wrong?
No. V x M = V x M works ONLY when the reactions coefficients are the same; i.e., 1:1, 2:2 etc.
How many moles MgCl2 do you have? That is M x L = ?moles MgCl2.
Now, using the coefficients in the balanced equation, convert moles MgCl2 to moles Na3PO4.
moles Na3PO4 = ?moles MgCl2 x (2 moles Na3PO4/3 moles MgCl2) = xmoles Na3PO4.
Finally, M Na3PO4 = moles Na3PO4/L Na3PO4. YOu have moles and M, solve for L, then convert to mL.
Thank you SO much.
Not only did you help me get the correct answer, but you helped increase my understanding of these problems.
Cheers to you.
what does the 'M' mean?
Yes, your set-up is correct! The equation V x M = V x M represents the equality between the moles of the reactants and the moles of the products in a chemical reaction. In this case, you are determining the volume (in milliliters) of Na3PO4(aq) that will react with a given volume (22.00 mL) of MgCl2(aq).
To solve for x (the volume of Na3PO4(aq)), you can use the formula:
(22.00 mL)(0.0800 M) = (0.0850 M)(x)
Now, let's solve for x:
(22.00 mL)(0.0800 M) = (0.0850 M)(x)
x = (22.00 mL)(0.0800 M) / (0.0850 M)
x ≈ 20.7059 mL
Since the given volume for Na3PO4(aq) is 22.00 mL, and we want to work with the correct number of significant figures, the final answer should be rounded to 4 significant figures, which gives us 20.71 mL.