A sample of 7.45 grams of NaOH is dissolved
into 609 mL of aqueous 0.250 M NaOH (as-sume no volume change). This solution is
then poured into 2.18 gallons of water. (You
may assume that the two volumes can be
added.) What is the concentration of NaOH
in the final solution?
Answer in units of M
.038214
WARNING! THIS IS ACADEMIC DISHONESTY! THIS IS PUNISHABLE!
To find the concentration of NaOH in the final solution, we need to calculate the moles of NaOH in the initial solution and then determine the final volume of the solution.
Step 1: Calculate the moles of NaOH in the initial solution.
We have a sample of 7.45 grams of NaOH. To find the moles, we need to use the molar mass of NaOH, which is 22.99 g/mol for Na + 16.00 g/mol for O + 1.01 g/mol for H = 39.99 g/mol.
Moles of NaOH = mass of NaOH / molar mass of NaOH
Moles of NaOH = 7.45 g / 39.99 g/mol
Step 2: Determine the final volume of the solution.
We are pouring the initial solution into 2.18 gallons of water. To calculate the final volume, we need to convert gallons to milliliters, as the molarity is given in units of M (moles per liter).
1 gallon = 3.78541 liters (approx.)
2.18 gallons = 2.18 * 3.78541 liters = 8.24661 liters
Final volume of the solution = volume of water + volume of initial solution
Final volume of the solution = 8.24661 L + 0.609 L (converting 609 mL to liters)
Step 3: Calculate the concentration of NaOH in the final solution.
Concentration (Molarity) = Moles / Volume
Concentration of NaOH = Moles of NaOH / Final volume of solution
Now, let's substitute the values into the equation:
Concentration of NaOH = (7.45 g / 39.99 g/mol) / (8.24661 L + 0.609 L)
Concentration of NaOH = (0.1862 mol) / 8.85561 L
Concentration of NaOH = 0.021 M (rounded to three decimal places)
Therefore, the concentration of NaOH in the final solution is 0.021 M.
7.45 g NaOH is how many mols? That's mol = grams/molar mass = ?.
609 mL of 0.250M NaOH is how many mols? That's M x L = ?
Add to obtain total mols.
Then convert 2.18 gallons to L, add to the 609 mL to obtain total volume. Then M final soln = total mols/total L solution.