mishallc2515Lv1

24 Jan 2023

Lab Component - Titration:  Determining the Concentration of Vinegar

Fill in charts and answer questions. 

Lab Data -
 

1. Write the properly balanced chemical equation for the reaction between vinegar (acetic acid) and sodium hydroxide.

 

Uncertainty:  is the range of possible values within which the true value of the measurement lies.  All measurements are subject to some uncertainty.  Uncertainty in equipment is accounted for by the use of + .  For example a reading of 11 + 1 means the "true value" is between 10 and 12.  The uncertainty of a measuring instrument in a chemistry lab is estimated as plus or minus half the smallest increment on the equipment.  For instance if a thermometer has a mark every 10C then the uncertainty is +0.50C so if a chemist reads a value of 240C it should be written down as 24.0 + 0.50C (note the reading lines up with the uncertainty).   Mechanical/Electrical devices have uncertainty that is listed when the equipment is bought.  

 

Table #1 - Uncertainty Values for Copper Cycle Reaction:

Equipment Uncertainty How many numbers to write down? SF?  Scale +0.001 g Three numbers to the right of the decimal. pipette +0.01 mL Two numbers to the right of the decimal.  Burette +0.05 mL Two numbers to the right of the decimal.

 

Procedure (for titration):

Watch the following video for the procedure of titration of acetic acid with NaOH.  

This is a two part experiment.  Vinegar titration

 

Observations:

Fill in the following tables:

Part A: Standardization of NaOH:

 

Table #1 - Titration of KHP vs NaOH:

Trial # 1 2 3 Mass of KHP       Initial Volume of NaOH       Final Volume of NaOH 32.75 mL (I think the picture is wrong shown here!)  If you read the burette it would be 30.30 mL       Other Observations (i.e. colour)       

 

Table #2 - Titration of vinegar vs NaOH

Trial # 1 2 3

Volume of vinegar (pipette measurement) 

 

      Volume of water added       Initial Volume of NaOH   4.38 mL (SF's are incorrect on her lab data collecting )    Final Volume of NaOH   31.73 mL (SF's are incorrect on her lab data collecting)   Other Observations (i.e. colour)       

 

 

Part A:  Calculation of the Molarity of the NaOH:

1.  Which trials will you NOT use and why?

2.  Fill in the following table:

Table #3 - Part A Calculations: 

Trial #        Average Mass of KHP      

Xxxxxxxxxxxxx

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Moles of KHP if the molar mass of KHP is 204.22 g/mol      

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Moles of NaOH if the mole ratio of NaOH: KHP is 1:1      

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Volume of NaOH used (Final - Initial)       

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Volume of NaOH used converted to Litres.       

Xxxxxxxxxxxxxxxx

Xxxxxxxxxxxxxxx

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[NaOH] = n/V        

3. Which trials will you NOT use and why?

4.  Fill in the following table: 

Table #4 - Part B Calculations: 

Trial #        Average Volume of Vinegar (pipetted)       

Xxxxxxxxxxxxx

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Volume of NaOH used (Final - initial)       

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Volume of NaOH used converted to Litres      

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxxx

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Moles of NaOH used (Average [NaOH] x Volume of NaOH)       

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Using the balanced chemical equation from the pre-lab calculate the moles of acetic acid.       

Xxxxxxxxxxxxx

Xxxxxxxxxxxxxx

Xxxxxxxxxxxxx

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Calculate the [acetic acid]         

 

Questions: 

1.  Why should you always pour into a burette at "stomach level" rather than above your head?

2. The following is a chart of the molar concentrations of acetic acid in commercial vinegars:

 

Table #5 - Concentrations of Commercial Vinegars:

Brand Molar Concentration Calculated % Allen's Red Wine 0.87 M 5.2 % Heinz Pickling 1.18 M 7.1 % No Name 0.87 M 5.2% President's Choice Aged Garlic Wine 0.99 M 6.0% Canada Cider 0.91 M 5.7% Marukan Rice Vinegar 0.71 M 4.3%

1. What type/brand of vinegar was titrated in this experiment?
2. What do you notice about pickling vinegar? Why do you think this is the case?

 

2.  Most shampoos are basic.  Why do some people rinse their hair with vinegar after washing it?