How many millimeters of this solution should be diluted with water to produce 650 mL of a solution with pH= 11.50? 6.8% ammonia (d= 0.97g/ml)
This is worked the same way as the one I did for you previously.
thnx
can u tell me what your final answer is? I got 7.96 * 10 ^5 ml.
To determine the number of millimeters of the solution that should be diluted with water, we need to consider the concentration of the solution, its density, and the desired volume and pH of the resulting solution. Let's break down the problem step by step:
1. Determine the concentration of the initial solution:
The initial solution has a concentration of 6.8% ammonia. This means that for every 100 mL of solution, there are 6.8 mL of ammonia.
2. Calculate the amount of ammonia in the initial solution:
To determine the amount of ammonia, we need to convert the volume of the initial solution to grams of ammonia using its density. The density of the solution is given as 0.97 g/ml.
Amount of ammonia = Concentration (%) x Volume (ml) x Density (g/ml)
Amount of ammonia = 6.8% x Volume (ml) x 0.97 g/ml
3. Calculate the amount of ammonia in the desired solution:
The desired solution will have a volume of 650 mL and a pH of 11.50. Since the pH value is given, we assume that the ammonia will be the component responsible for achieving this pH. To calculate the amount of ammonia needed, we can use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
In this case, A- represents the concentration of the conjugate base (ammonia) and HA represents the concentration of the acid (ammonium ion). Ammonium ion is acidic, while ammonia is basic. The pKa value for the NH4+/NH3 couple is approximately 9.24. Since we know the pH and want to find the concentration of ammonia, we can rewrite the equation as:
[A-]/[HA] = 10^(pH - pKa)
We want a pH of 11.50, so:
[A-]/[HA] = 10^(11.50 - 9.24)
[A-]/[HA] = 245.08
This means that there should be 245.08 times more ammonia than ammonium ion in the solution.
4. Solve for the amount of ammonia needed:
Let's assume that the volume of the ammonia solution to be diluted is 'x' mL. So, the concentration of ammonia in the desired solution would be (x * 6.8%) / 650 mL. Since the concentration of ammonia should be 245.08 times that of the ammonium ion, we can set up the following equation:
(x * 6.8%) / 650 mL = 245.08
Solve for 'x':
x * 0.068 = 245.08 * 650
x = (245.08 * 650) / 0.068
x ≈238,294.12 mL
Therefore, approximately 238,294.12 mL of the solution should be diluted with water to produce 650 mL of a solution with a pH of 11.50.