A solution containing 10.mmol of CO₃^2-and 5.0 mmol of HCO₃^-is titrated with 1.2 M HCl.What volume of HCl must be added to reach the first equivalence point? (1 mmol = 0.001 mol) A) 23.3 mL B) 4.2 mL C) 8.3 mL D) 18.3 mL E) 13.3 mL

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The first step is to write the balanced chemical equation for the reaction between CO₃²F1F1F1S1^F1F1F10and HCl: CO₃²F1F1F1S1^F1F1F10+ 2HCl → CO₃F1F1F1S1^F1F1F10 + H2O + 2Cl- From the balanced equation, we can see that the mole ratio of CO₃²F1F1F1S1^F1F1F10to HCl is 1:2. Therefore, to reach the first equivalence point, we need to add 20 mmol of HCl (2 x 10 mmol of CO₃²F1F1F1S1^F1F1F10). Now we can use the formula: V1 x N1 = V2 x N2 where V1 is the volume of HCl added, N1 is the normality of HCl (1.2 M = 1.2 N), V2 is the volume of the solution being titrated (in liters), and N2 is the normality of the solution being titrated (which is equal to the number of mmol of CO₃²F1F1F1S1^F1F1F10and HCO₃F1F1F1S1^F1F1F10in 1 liter of solution, which is 10 mmol CO₃²F1F1F1S1^F1F1F10 + 5.0 mmol HCO₃F1F1F1S1^F1F1F10 = 15 mmol)). Substituting the values and solving for V1, we get: V1 = V2 x N2 / N1 V1 = 1 L x 15 mmol / 1.2 N V1 = 12.5 mL Therefore, the answer is C: 8.3 mL (rounded to the nearest tenth).

A Solution Containing 10