Hi there, maybe dumb question but how would I find the initial concentration of Fe^3+??
In lab, we mixed these reactants into one test tube:
-0.50mL of 0.0025M Fe(NO3)3
-0.50mL of 0.0025M KSCN
-2.50mL of 0.10M HNO3
The net ionic equation for the experiment is:
Fe^3+(aq) + SCN^-(aq) <-> FeSCN^2+(aq)
Molarity is mol/volume in L, but we're given 0.0025mol of Fe in this case, but what volume would I use to divide in order to find the initial concentration of Fe^3+? Would I use the volume of the Fe^3+ added into the mix or the total volume of the entire test tube??
Thanks in advance
To find the initial concentration of Fe^3+, you need to consider the volume of the Fe(NO3)3 solution that was added to the mixture. In this case, you added 0.50 mL of a 0.0025 M Fe(NO3)3 solution to the test tube.
Since molarity is defined as moles per liter (mol/L), you need to convert the volume of Fe(NO3)3 to liters.
To do this, divide the volume by 1000, since there are 1000 mL in a liter:
0.50 mL ÷ 1000 = 0.00050 L
Next, find the number of moles of Fe(NO3)3 that you added to the mixture. You can use the molarity and volume of the Fe(NO3)3 solution:
Moles of Fe(NO3)3 = Molarity × Volume in liters
= 0.0025 M × 0.00050 L
= 0.00000125 mol
Since Fe(NO3)3 dissociates to produce 1 Fe^3+ ion, the initial concentration of Fe^3+ in the solution is the same as the number of moles of Fe(NO3)3:
Initial concentration of Fe^3+ = 0.00000125 M
Thus, the initial concentration of Fe^3+ in the mixture is 0.00000125 M.