You are a work study student in our chemistry department. Amy, your supervisor has just asked you to prepare 250ml of 3.00M H2SO4 solution for tomorrow's undergraduate experiment. The Stock Solutions cabinet is under the Stockroom Explorer. You will find find a 2.50 liter bottle containing 17.8M H2SO4. Please prepare a flask containing 250ml of a 3.00M solution. To ensure proper credit, please write your calculations in the space given below.
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In designing your procedure, it is useful to remember that diluting a substance does not change the amount of that substance. So the number of moles of the substance before the dilution is the same as the number of moles after the dilution (conservation of matter). The number of moles in solution is given by the concentration (C in moles/liter) multiplied by the volume (V in liters). So the conservation of matter implies:
C1V1 = C2V2
where C is concentration and V is volume. 1 labels the solution before the dilution and 2 labels the solution after the dilution. (This expression is based on the number of moles of the substance between the same before and after the dilution, with C (moles/liter) * V (liter) = moles).
Important: Please describe your complete procedure and the key quantities you measure. Points are based on whether or not you explain your procedure in sufficient detail for us to know what you did. You are not graded on the method you used; all approaches that produce accurate results are fine.
To prepare a 250 ml of 3.00M H2SO4 solution using a 2.50 liter bottle of 17.8M H2SO4 stock solution, you can follow these steps:
1. Use the equation C1V1 = C2V2, where C1 is the concentration of the initial solution, V1 is the volume of the initial solution, C2 is the desired concentration of the final solution, and V2 is the desired volume of the final solution.
2. From the question, we know the initial concentration (C1) is 17.8M, the initial volume (V1) is 2.50 liters, the desired concentration (C2) is 3.00M, and the desired volume (V2) is 250 ml (which can be converted to liters by dividing by 1000).
3. Substitute the known values into the equation: (17.8M) * (2.50L) = (3.00M) * (V2).
4. Solve for V2: V2 = (17.8M * 2.50L) / 3.00M.
5. Calculate the volume of the stock solution needed to make the desired solution: V_stock = V2 - V_final.
6. Substitute the known values into the equation: V_stock = (17.8M * 2.50L) / 3.00M - V_final.
7. Calculate the volume of the stock solution needed: V_stock = (17.8M * 2.50L) / 3.00M - 0.250L.
8. Simplify the equation: V_stock = 14.83L - 0.250L = 14.58L.
9. Convert the volume of the stock solution needed from liters to milliliters: V_stock_ml = V_stock * 1000.
10. Calculate the volume of the diluent (water) needed to reach the final desired volume: V_diluent = V_final - V_stock.
11. Substitute the known values into the equation: V_diluent= 0.250L - V_stock.
12. Simplify the equation: V_diluent = 0.250L - 14.58L = -14.33L.
13. Convert the volume of the diluent needed from liters to milliliters: V_diluent_ml = V_diluent * 1000.
14. To prepare the solution, measure 14.58 ml of the stock solution and add it to a flask. Then, add enough water to the flask to reach a total volume of 250 ml.
Remember to record all calculations and measurements accurately to ensure proper credit.