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Q.1) Orange squash concentrate from a bottle is poured into 2 beakers as shown below. The concentrate contains 2.0 g of vitamin C per 100 cm3
Which is the more concentrated solution, that in beaker A or B _____________
Which beaker contains the most vitamin C, beaker A or B?

Q.2) A 25 cm3
aliquot (or portion) of squash from the bottle is pipetted into each of two beakers, Beaker X is wet and Beaker Y is dry. Which is the more concentrated, the contents of beaker X or Y? ___________ Which beaker contains more vitamin C?

Q.3) A 25 cm3
sample of squash is transferred from beaker A with two different zipettes, one of which is dry and one of which is wet, and each sample is placed in a conical flask, identified as Pdry and Pwet respectively.
 

Production and Purification of Aspirin

This experiment involves production of aspirin. The major reactants which were used in the experiment include salicylic acid HC7H5O3, and C4H6O3. The reactants reacted in order to produce acetylsalicylic acid or simply aspirin HC9H7O4 and ethanol acid CH3CHOOH. Asprin has several uses such as an analgesic or painkiller, as an anti-pyretic or fever reducer and as thinning of the blood.

Balanced equation HC7H5O3 + C4H6O3 = HC9H7O4 + CH3CHOOH

Moles ratio    1 1 1 1

= Results and Calculation

Available results:

Salicylic acid mass= 3.2888 g

Experiment yield of Aspirin:  =3.625g

Acetic Acid Anhydride density:  1.1 g/mL

Acetic acid anhydride volume: 10mL

Moles of salicylic acid:

HC7H5O3 Molar mass = 138g/mol as given
number of moles = HC7H5O3 grams/ HC7H5O3 molar mass

Moles =3.2888g/138g/mol= 0.0238319 moles

Acetic acid anhydride moles:

C4H6O3 Molar mass =102g/mol

Acetic acid density=1.1g/mL

Mass = density times volume

acetic acid anhydride mass=1.1g/mL × 10mL=11

number of moles =grams/molar mass

Acetic acid anhydride Moles =11g/102g/mol=0.1078431moles 

In this case, the limiting reagent was found using the moles ratio indicated as the ration of Salicylic acid moles to acetic acid moles

From the equation, the mole ration is 1:1

Therefore, theoretically, 1 mole of acetic acid anhydride = 1 mole of salicylic acid. This means that the moles for salicylic acid will be 0.0238319 theoretically.

∴in conclusion, comparing the theoretical and calculated mole ration for acetic acid anhydride, we find that, the theoretical 0.0238319 mol of acetic acid anhydride is less than the actual amount of 0.1078431mol of acetic acid anhydride. This means that salicylic acid will be the limiting reagent while acetic acid anhydride is the excess reagent.

In this part, we use the limiting reagent and its mole ratio to find the moles of asprin from the experiment.

The ration of moles of HC7H5O3 to HC9H7O4 moles is 1:1

∴ This means that the moles for the two reagents will be the same. That is 0.0238319 moles for HC9H7O4 and the same moles for HC7H5O3.

The theoretical yield of ASA (in g)

Finding the molar mass of HC9H7O4:

The molar mass of HC9H7O4 will be 180g/moles as indicated

Calculating theoretical mass of HC9H7O4

HC9H7O4 grams = moles × molar mass

0.0238319 mol ×180g/mol=4.289742g

As from the experiment, the actual yield of HC9H7O4 was 3.625g

Percentage yield will therefore be:

% yield= {(actual yield)/(theoretical yield)}×100

% yield= {(3.625g/4.289742g)}100

% yield=84.503917%

∴ the % yield of aspirin is therefore 84.50% representing 3.625g of a maximum of 4.2897g theoretical value.

In conclusion, it was clear that the theoretical and experiment values of produced aspirin are different. The experiment in this case is used to determine the yield and melting point of the products which are determined through confirmatory test. The limiting reagents in the experiment were determined in order to help to calculate the theoretical yield.

Recrystallisation of Benzoic Acid

Title: purification of an organic compound by recrystallisation   

Introduction

This experiment involves the purification of benzoic acid through recrystallisation process. The insoluble impurity used is carbon and water soluble impurity is citric acid. Recrystallisation method was used in the determination of the melting point of the impure compound and separation of the solids. Materials can be contained in other and be insoluble when cold but soluble when hot and vice versa. Comparison of the melting point ranges was also carried out in this experiment.

Impure compound weight 1.110

Water 35 cm

 Weight of filter glass 26.4199

Weight of clock glass is 26.835

Benzoic acid weight  0.416 gm   

% Recovery of Pure Benzoic Acid = Weight of dry pure benzoic acid x 100

                                                                 Weight of impure compound used
= (0.1416/1.11)*100 = 12.76%

In conclusion, through this experiment, it was clear that the substances with similar molecules are considered pure and have different melting points with impure substances. Cooling filtrate makes the pure substances to recrystallise out into small quantities. This was the key method which was used to purify the substances in this experiment. The recovery percentage was important to show the rate of purification of the substance.

Title: Determination of the percentage Sodium Carbonate in a sample of commercial Washing Soda.  

This experiment involved production of sodium carbonate from washing soda. The preparation of the Sodium Carbonate is done from commercial washing soda through titration process. In order to neutralize sodium carbonate, two parts of hydrochloric acid are needed. First, the soda was measured and then transferred to the clockglass. Water was added and the mixture was titrated with HCL until color change to pink was experienced. Titration process was also important in this experiment.

Na2CO3    +   2HCl à    2NaCl   +    H2O    +    CO2

Calculation

Washing soda of 25ml

Weight of clock glass 23.44g

2 drops of indicator gives 25g

6 of HCL = 10 cm3 x 6 = 60 cm3

Moles of HCL use = 60* 0.1 / 1000 =0.006 moles

  The balanced equation of the reaction will be:

   Equation                  Na2CO3+2HCl = 2NaCl   +    H2O    +    CO2

 Moles representation     1 mole            2 moles     2 moles       1 mole      1 mole

Using the ration, Na2CO3 used  moles                                          = 0.006 / 2

                                                                                                  = 0.003

Determination of Percentage Sodium Carbonate in Washing Soda

Na2CO3 Molar mass  = 25g/mol

Mass of Na2CO3 available in 25 cm3                                                             = 0.003 x 25 g

                                                                                                           = 0.075 g

Mass of Na2CO3 available in 250 cm3                                                           = 7.5 g

Mass of Na2CO3.xH2O available in 250 cm3                              = 25 g

water mass available in this amount of Na2CO3.xH2O      =25-7.5 = 17.5 g

Percentage of water available in Na2CO3.xH2O                         = 70.00%

Moles of water present in this amount of Na2CO3.xH2O         = 17.5 / 18

= 0.97722222

Moles of Na2CO3 present in this amount of Na2CO3.xH2O   = 0.0097

Value of x in Na2CO3.xH2O                                                   = 0.9722 / 0.0097

                                                                                                              =  10                                                                                          

Formula of hydrated sodium carbonate:                                   = Na2CO3.10H2O        

In conclusion, the production of sodium carbonate was done through the use of several reactants. HCL was used in the titration process. The amount of sodium carbonate produced was depended on the reactants and their status.

Lesson 9

1.4 preparations of standard solutions

1

The molar mass of oxalic acid dihydrate is 126 g/mol

Weight needed to prepare 1000 cm3 of a 1.0 molar solution 126 g

Weight needed to prepare 250 cm3 of a 1.0 molar solution 31.5 g

Weight needed to prepare 250 cm3 of a 0.1 molar solution 12.6 g

To prepare a standard solution of sodium carbonate

Sodium carbonate is available as pure anhydrous sodium carbonate and is also available in an impure hydrated form (washing soda).

The molar mass of sodium carbonate, Na2CO3 is 106 g/mol

Weight needed to prepare 250 cm3 of a 1.0 M solution 26.5 g

Weight needed to prepare 250 cm3 of a 0.05 M solution 1.325 g

Acids and bases may be strong or weak.

They may be concentrated or dilute.

Common strong acids are:

HCl, which is named as ________hydrocloric acid

H2SO4, which is named as  sulphiric acid  

HNO3, which is named as nitric acid

Common weak acids are:

Ethanoic acid, which has the formula: _CH3COOH

Oxalic acid, which has the formula: _ (COOH)2 

Answer the following:

Which is the stronger acid, 0.1 M HCl or 5 M ethanoic acid?: 0.1 M HCl  

Which is the more concentrated acid? 5 M ethanoic acid

1.6 Experimental technique for volumetric analysis

It is important to understand when the dilution of a solution will affect a result and when it will not.

Think carefully about each step in the following sequence and answer the questions.

Q.1) Orange squash concentrate from a bottle is poured into 2 beakers as shown below. The concentrate contains 2.0 g of vitamin C per 100 cm3.

Which is the more concentrated solution, that in beaker A or B  beaker A_

Which beaker contains the most vitamin C, beaker A or B? beaker B

Q.2) A 25 cm3 aliquot (or portion) of squash from the bottle is pipetted into each of two beakers, Beaker X is wet and Beaker Y is dry.

Which is the more concentrated, the contents of beaker X or Y?  beaker Y

Which beaker contains more vitamin C? beaker X

Q.3) A 25 cm3 sample of squash is transferred from beaker A with two different pipettes, one of which is dry and one of which is wet, and each sample is placed in a conical flask, identified as Pdry and Pwet respectively.

Which conical flask contains more vitamin C? Pwet 

Give a reason for your answer:

Since it wet, the beaker will need more vitamin C to titrate until the color changes

Cite This Work

To export a reference to this article please select a referencing stye below:

My Assignment Help. (2020). Experiments In Chemistry. Retrieved from https://myassignmenthelp.com/free-samples/vomp3003-synthesis-of-acetylsalicylic-acid-for-percentage-yield.

My Assignment Help (2020) Experiments In Chemistry [Online]. Available from: https://myassignmenthelp.com/free-samples/vomp3003-synthesis-of-acetylsalicylic-acid-for-percentage-yield
[Accessed 02 March 2024].

My Assignment Help. 'Experiments In Chemistry' (My Assignment Help, 2020) <https://myassignmenthelp.com/free-samples/vomp3003-synthesis-of-acetylsalicylic-acid-for-percentage-yield> accessed 02 March 2024.

My Assignment Help. Experiments In Chemistry [Internet]. My Assignment Help. 2020 [cited 02 March 2024]. Available from: https://myassignmenthelp.com/free-samples/vomp3003-synthesis-of-acetylsalicylic-acid-for-percentage-yield.

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