25.0mL of an acidic 0.100 mol/L tin (II) chloride solution required an average volume of 12.7 mL of potassium dichromate solution for a complete reaction. The amount of concentration of the potassium dichromate solution is _______ mmol/L
How do you go about solving this? I think that the 5 step method is involved in finding a solution :/ Please help!! My test is tomorrow :( thanksss!!
To solve this problem, you can use the 5-step method in analytical chemistry. Here's how you can apply it:
Step 1: Write the balanced chemical equation for the reaction.
Based on the given information, the reaction can be written as follows:
SnCl2(aq) + Cr2O7^2-(aq) → SnCl4(aq) + Cr^3+(aq)
Step 2: Determine the stoichiometry of the balanced chemical equation.
From the balanced equation, you can see that the stoichiometry of tin (II) chloride (SnCl2) and potassium dichromate (Cr2O7^2-) is 1:1.
Step 3: Calculate the number of moles of tin (II) chloride used.
Given that the volume of tin (II) chloride solution is 25.0 mL (0.025 L) and the concentration is 0.100 mol/L, you can calculate the number of moles as follows:
moles of SnCl2 = 0.025 L * 0.100 mol/L = 0.0025 mol
Step 4: Calculate the number of moles of potassium dichromate used.
Given that the volume of potassium dichromate solution used is 12.7 mL (0.0127 L) and the stoichiometry is 1:1, the number of moles of potassium dichromate is the same as the number of moles of tin (II) chloride:
moles of Cr2O7^2- = 0.0025 mol
Step 5: Calculate the concentration of the potassium dichromate solution.
To find the concentration in mmol/L, you need to convert the moles of potassium dichromate to millimoles and divide it by the volume of the solution used. In this case, that is:
concentration of Cr2O7^2- = (0.0025 mol / 0.0127 L) * 1000 = 196.85 mmol/L
Therefore, the concentration of the potassium dichromate solution is approximately 196.85 mmol/L.
Remember to always double-check your calculations and units to ensure accuracy. Good luck on your test!