Need answers to 1C and 2, 3!! 1. Record your results for each of the 3 trials: 2

Question

Need answers to 1C and 2, 3!!

1. Record your results for each of the 3 trials:

2. Calculate the concentration of the CoCl2 solution (moles/L)

3. What is the average concentration of the CoCl2 solution? To how many significant digits can this concentration be reported? (Consider the accuracy of the burette and the volume in one drop.)

The concentration of the cobalt(II) chloride solution is determined by comparing the concentrations of the titrant and titrate. The equation for the chemical reaction between cobalt chloride and sodium hydroxide is:

CoCl2(aq) + 2NaOH (aq) 2NaCl (aq) + Co(OH)2(s)

At the endpoint, exactly enough NaOH has been added to remove the cobalt ions from the solution in the form of the solid precipitate, Co(OH)2. Notice, however, that 2 molecules of NaOH are required to react with one molecule of CoCl2. Therefore, if we know the total moles of NaOH used in the titration, then there will have been half as many moles of CoCl2in the titrated sample.

This means that we must adjust the familiar formula for a titration to account for the ratio in which the CoCl2 and NaOH react:

(Moles of CoCl2 ) = (Moles of NaOH) ÷ 2

which can be expressed in terms of concentrations as:

C1 Ý V1 = (C2 Ý V2) ÷ 2

where:

C1 is the concentration of the CoCl2

V1 is the volume of the CoCl2 solution being titrated

C2 is the concentration of the NaOH solution

V2 is the total volume of NaOH added up to the endpoint

THERE IS NO MORE INFORMATION PROVIDED BY THE LAB

the NaOH used was 0.1 M

a Volume of CoCl2 (mL)   10.00
  
10.00
10.00 b Volume of NaOH added (mL) 17.91
   17.96
  
17.98 c Concentration of NaOH added

Explanation / Answer

1C ) concentration of NaOH added to the each solution = 0.1 M

2) concentration of the CoCl2 for first trail can be calculated by using formula given C1xV1=(C2xV2)/2

substitute the all values in above equation C1=(0.1 x 17.91 )/(2x10)

C1=0.0895

similarly second trail C1=(0.1 x 17.96 )/(2x10)

C1=0.0898

third taril C1=(0.1 x 17.98 )/(2x10)

C1= 0.0899

3) avarage concentration of CoCl2 =(0.0899+0.0898+0.0895)/3

= 0.0897 M

answer can reported in four significant digits .

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