A liquid solution of formaldehyde is 37.0% pure. This solution has a specific gravity of 1.037. The molecular weight of formaldehyde is 30.0. to 1.00 ml of this impure stock solution is added quantity sufficient to take the total volume to 500ml. If 1.00 ml of this solution is added to 4ml of water in a final reaction, what is the molarity of formaldehyde in this final reaction tube?
Thank you!!!!
What's the molarity of the solution?
1,000 mL x 1.037 g/mL x 0.37 = ?g HCHO.
?g HCHO/molar mass = moles and that is the molarity since the solution is 1 L.Abut 13M but you need to do that more accurately than I.
final M = about 13M x (1.00/500) x (1.00/5.00) = ?
(Note: Technically we can't calculate the final M since the final dilution takes 1.00 mL and ADDS 4.00 mL water. The last step of the above calculation depends upon the 1.00 mL adding to 4.00 mL to give 5.00 mL. The way dilutions are made is that you would add 1.00 mL to enough water to make the total volume equal to 5.00 mL. In reality, I'm not sure we would be able to measure the difference.
To find the molarity of formaldehyde in the final reaction tube, we need to follow a series of steps:
Step 1: Calculate the amount of formaldehyde in the 1.00 ml stock solution.
The stock solution is 37.0% pure formaldehyde. So, the amount of formaldehyde in 1.00 ml of the stock solution is:
(37.0% / 100%) x 1.00 ml = 0.370 ml
Step 2: Calculate the total volume of the final solution.
1.00 ml of the impure stock solution is added to the quantity sufficient to bring the total volume to 500 ml. So, the final volume is:
1.00 ml + quantity sufficient = 500 ml
quantity sufficient = 500 ml - 1.00 ml = 499 ml
Step 3: Calculate the volume of formaldehyde in the final solution.
The volume of formaldehyde in the final solution will be the same as the volume in the stock solution, as no additional formaldehyde is added to the reaction. So, the volume of formaldehyde in the final solution is 0.370 ml.
Step 4: Calculate the molarity of formaldehyde in the final solution.
Molarity is defined as moles of solute per liter of solution. Since the formaldehyde has a molecular weight of 30.0, we need to convert the volume (in ml) to liters and calculate the moles of formaldehyde.
Number of moles of formaldehyde = volume of formaldehyde (in liters) x concentration (in moles/liter)
Concentration (in moles/liter) = amount of formaldehyde / molecular weight
Concentration (in moles/liter) = (0.370 ml / 1000 ml/L) x (37.0 g/100 ml) / 30.0 g/mol = 0.001217 mol/L
Note: We converted the volume from ml to L by dividing by 1000, and the concentration was obtained by dividing the amount of formaldehyde by the molecular weight.
Step 5: Calculate the molarity of the final reaction tube.
1.00 ml of the solution containing 0.001217 mol/L of formaldehyde is added to 4 ml of water in the final reaction.
The final volume of the reaction tube is 5.00 ml (1.00 ml + 4.00 ml).
Now, we can calculate the molarity:
Molarity = moles of solute / volume of solution (in liters)
Molarity = 0.001217 mol / (5.00 ml / 1000 ml/L) = 0.2434 mol/L
So, the molarity of formaldehyde in the final reaction tube is 0.2434 mol/L.