Rough1234 Initial Final Total Should another titration be done? Why or why not?

 Find the average titre volume.  /3=15.1mL  3 results within.1mL are called concordant results  (exclude trial 1 since it is more than.1 away from the rest) Rough1234 Initial Final Total

 Remember that c=n/V  c=concentrantion  n=moles  V=volume (in L)

1. Identify the known and the unknown in the problem. 2. Find the amount of moles of the known using the c=n/V equation. 3. Look at the balanced equation to find the mole ratio and multiply the moles of the known by the mole ratio (unknown/known) to find the moles of the unknown. 4. The concentration of the unknown can be calculated from the moles calculated above and the volume from the titration.

15.0 mL of an aqueous solution of mol L -1 sodium carbonate is titrated with hydrochloric acid solution.12.6mL of solution is needed to reach the equivalence point. What is the concentration of the sodium carbonate solution? 2 HCl (aq) + Na 2 CO 3(aq)  2 NaCl (aq) + CO 2(g) + H 2 O (l)

HClNa 2 CO 3 ratio21 n c0.105 mol L -1 V L

 Calculate moles of known – sodium carbonate  n=c*V  n=0.105*0.015L  n= mol

HClNa 2 CO 3 ratio21 n mol c0.105 mol L -1 V0.0126L0.0150L

Find the number of moles of unknown using mole ratio and moles of known. = mol *(unknown/known) = mol * 2/1 = mol of HCl

HClNa 2 CO 3 ratio21 n m ol mol c0.105 mol L -1 V0.0126L0.0150L

 Calculate concentration of unknown  c=n/V  c= mol/0.0126L  c=0.250mol L -1

HClNa 2 CO 3 ratio21 n mo l mol c0.250 mol L mol L - 1 V0.0126L0.0150L

 2HCl (aq) + Ca(OH) 2(aq)  CaCl 2(aq) + 2H 2 O (l)  We know the following…  V = 50.0 mL Ca(OH) 2 in flask  [HCl] = mol L -1  V HCl added = 20.0 mL for 3 concordant titres.