Question

Question 10 Question; Suppose you believe your unknown compound is Na2CO3, and you also prepare 20 mL of a 0.1 mol/L solution of it. Using a 0.2 mol/L HCl solution as the titrant, what volume of HCl (in mL) is needed to reach the equivalence point when methyl orange turns red? Hint: . Write the chemical reaction with Na2CO3 and HCl as reactant first, and then balance the chemical reaction. . The conceptual plan above still helps the flow of the calculation. But the stoichiometry ratio is different, which is determined by the balanced chemical reaction.

Answer 1

The unknown compound is Na2CO3 Volume -20 mL Molarity = 0.1 mol / L Moles of Na2CO3- Molarity x volume 1L 103 mL =0.1mol / L x20 mL x--=0 The equation for the reaction between Na,CO3 and HCl is as follows: Na, CO, + 2 HCl → 2 NaCl+ H2CO3 Moles of HCl required to react with 1 mole Na,CO3 is 2 moles So moles of HCl = 2 x 0.002 moles 0.004 moles Molarity of HCl 0.2 mol /L Volume of HCI-moles -0.004 moles molarity 0.2 mol/L Volume of HCI- = 0.02 L or 20 molarity 02 mol/L 002L or 20mL