A student is setting up a fish tank. To create an acidic fish tank environment, the student takes 2 L of a 2 M acid and dilutes it with
water to make a final solution of 50 L What is the final molarity or [H] of the fish tank?
M1V1 = M2V2
M1 = 2 M
V1 = 2 L
V2 = 50 L
M2 = (M1V1)/V2
M2 = (2 M)(2 L)/(50 L)
M2 = 0.08 M or [H] = 0.08 mol/L.
I should point out that this answer is true only for strong acids. It will not work for weak acids.
Thank you for pointing that out. You are correct that this calculation assumes that the acid is a strong acid and will fully dissociate in water. For weak acids, the calculation becomes more complicated and takes into account the acid dissociation constant and the pH of the solution.
To find the final molarity or [H] of the fish tank, we can use the concept of dilution.
The initial volume and concentration of the acid are given as:
Volume (V1) = 2 L
Concentration (C1) = 2 M
The final volume of the solution after dilution is:
Volume (V2) = 50 L
Using the dilution formula, which states that the initial concentration times the initial volume is equal to the final concentration times the final volume, we can calculate the final molarity.
C1V1 = C2V2
(2 M) (2 L) = C2 (50 L)
Simplifying the equation:
4 M·L = 50 C2·L
Dividing both sides by 50 L:
C2 = (4 M·L) / 50 L
C2 = 0.08 M
Therefore, the final molarity or [H] of the fish tank is 0.08 M.
To find the final molarity or [H] of the fish tank, we can use the concept of dilution.
Dilution is the process of adding more solvent (in this case, water) to a solution to decrease the concentration of the solute (in this case, acid). The total moles of the solute before and after dilution should remain the same.
First, let's calculate the initial number of moles of acid in the 2 L of 2 M solution.
Molarity (M) is defined as moles of solute per liter of solution. Therefore, 2 M means there are 2 moles of acid in 1 liter of solution. Since we have 2 liters of solution, the initial number of moles of acid is:
2 M * 2 L = 4 moles of acid
Now, let's calculate the final molarity or [H] of the fish tank after dilution.
Using the concept of dilution, we know that the number of moles of acid remains the same, but the volume of the solution increases from 2 L to 50 L. Therefore, the final molarity can be calculated as:
Final Molarity = Initial Moles of Acid / Final Volume of Solution
Final Molarity = 4 moles of acid / 50 L = 0.08 M
Therefore, the final molarity or [H] of the fish tank is 0.08 M.