A volume of 10cm^3 of 2M H2SO4 is placed in a volumetric flas of 250cm^3 and filled to the mark with distilled water. What is the molar conc. of the H2So4 in the flask?
After I found how many moles there are in 10cm^3, which is 0.02 mol, what is my next step, as because the substance is diluted to the mark, I'm not sure whether the number of moles stays the same or changes ... :(
Thanks in advance! Any help is greatly appreciated :D
You have not changed the number of moles in the solution; however, you have changed the volume. Therefore the new concentration is simply the number of moles divided by the new volume in liters.
You mean 0.02 mol/250cm³?
thanks
Woops I was mistaken!
0.02/0.25L ... the answer comes 0.08moldm^-3!
thanks a million
That't right.
To find the molar concentration of the H2SO4 in the volumetric flask, you need to consider the dilution that occurs when the flask is filled to the mark with distilled water.
Here are the steps to determine the molar concentration:
1. Calculate the initial number of moles of H2SO4 in the 10cm^3 solution by multiplying the volume (10cm^3) by the molar concentration (2M). This gives you 0.02 moles of H2SO4.
2. Determine the final volume of the solution after dilution. The volumetric flask has a total volume of 250cm^3, so the final volume of the diluted solution is 250cm^3.
3. Use the principle of dilution to relate the initial and final concentrations. The number of moles of solute (H2SO4) remains constant before and after dilution. Therefore, the initial moles of H2SO4 (0.02 mol) will remain the same in the final diluted solution.
4. Calculate the molar concentration of the diluted solution using the formula:
Molar Concentration = Moles of Solute / Volume of Solution (in liters)
Convert the final volume from cm^3 to liters by dividing by 1000. In this case, the final volume is 250cm^3 = 0.25 liters.
Molar Concentration = 0.02 mol / 0.25 L = 0.08 M
Therefore, the molar concentration of the H2SO4 in the volumetric flask is 0.08M.
Remember that when a solution is diluted, the number of moles of the solute remains constant, but the volume increases, resulting in a lower molar concentration.