how can i prepare this solution?
Dissolve 24.82g of sodium thiosulphate in each cubic decimeter of solution to make astock of 0.1M. Dilute this solution 20-fold. URGENT PLEASE!!!!!!!!!!!!!!!
To prepare the solution, follow these steps:
1. Calculation of the grams of sodium thiosulphate required:
- You need to dissolve 24.82g of sodium thiosulphate in each cubic decimeter (dm³) of solution.
- The stock solution is prepared at a concentration of 0.1M (moles per liter).
To calculate the number of moles required (n), use the formula:
n = concentration (M) x volume (L)
In this case,
n = 0.1M x 1dm³
= 0.1 moles
Sodium thiosulphate has a molecular weight of 158.11g/mol.
To calculate the grams required (m), use the formula:
m = moles (n) x molecular weight (MW)
In this case,
m = 0.1 moles x 158.11g/mol
= 15.81g
Therefore, you will need to dissolve 15.81 grams of sodium thiosulphate in 1dm³ (or 1000mL) of water to make a stock solution of 0.1M.
2. Dilution of the stock solution:
- You mentioned that you want to dilute this solution 20-fold.
- This means you want to decrease the concentration of the stock solution by a factor of 20.
To do this, follow the formula:
C1V1 = C2V2
Where:
C1 = initial concentration
V1 = initial volume
C2 = final concentration
V2 = final volume
In this case, the initial concentration is 0.1M and the final concentration is 0.1M / 20 = 0.005M.
Substituting the values into the formula:
(0.1M) * V1 = (0.005M) * (20 * V1)
Solving for V1:
V1 = (0.005M * 20 * V1) / 0.1M
V1 = (0.1 * V1) / 0.1
V1 = V1
Therefore, you should dilute the stock solution with 20 parts (V1) of water or any appropriate solvent to achieve the desired concentration of 0.005M.
Remember to always perform calculations carefully, double-check your measurements and ensure proper lab safety procedures are followed when handling chemicals.