EXPERIMENT #4 – PREPARATION OF o-CHLOROBENZOIC ACID

1. PREPARE A SOLUTION OF CuCl AS FOLLOWS: Dissolve CuSO4∙5H2O (2.34 g) and pure NaCl (0.62 g) in water (8 mL) in a 50 mL Erlenmeyer flask. Warm on a hot plate to dissolve. Add a solution of sodium bisulphite (0.56 g) in water (6 mL) to the hot solution, with constant shaking over a period of about 5 minutes. Cool to room temperature in an ice bath, and decant the supernatant liquid from the colourless CuCl. Wash the precipitate twice by decantation with water containing a little (approximately 1% (v/v) solution) sulphurous acid (HSO3 ‐ + H+ →H2SO3), to prevent oxidation. Dissolve the CuCl in concentrated HCl (4 mL). Stopper the flask and cool in an ice‐salt mixture (0‐5oC) while the diazonium salt is being prepared.

2. PREPARE A DIAZONIUM SALT AS FOLLOWS: In a 125 mL conical flask, dissolve o‐ aminobenzoic acid (anthranilic acid, 0.94 g) in a solution containing conc. HCl (1.4 mL) and water (8.2 mL). Cool the solution to 0 oC. Slowly add a cold solution of NaNO2 (0.46 g) in water (1.6 mL). Do not allow the temperature to rise above 10 oC during this procedure. Add a small amount of urea (a few crystals) to the mixture and cool the resulting solution in an ice bath.

3. PREPARE o-CHLOROBENZOIC ACID AS FOLLOWS: Transfer the cold CuCl solution to a 150 mL beaker. Slowly add, with stirring (use long glass rod), the cold diazonium salt solution to the cold CuCl solution. Watch for foaming. Allow the mixture to stand for 20 minutes at room temperature with frequent stirring. Vacuum filter the precipitated o-chlorobenzoic acid and wash the product with a small amount of cold water.

4. RECRYSTALLIZE AS FOLLOWS: Clean the Buchner funnel and place it along with a 500 mL vacuum flask into the oven at 105 oC. In a 150 mL beaker, add the crude product, a small amount of charcoal, water (~20 mL) and ethanol (~2.6 mL). Heat to a gentle boil, stirring the mixture periodically. When the product has dissolved, quickly filter through the hot Buchner funnel (PRERINSE FILTER PAPER WITH BOILING WATER) in order to remove the charcoal before the o‐chlorobenzoic acid is allowed to 26 crystallize. Allow to cool to room temperature. Vacuum filter the recrystallized product. Dissolve a few crystals of the product in ethanol and spot it on a TLC plate and label it “R”. Likewise dissolve a few crystals of anthranilic acid in ethanol and spot that on a TLC plate as well, labelling it as “SM”. Develop the TLC plate as usual, taking note of the solvent used. Determine the m.p. and percent yield of the dried product next week while doing experiment #5.

If the experiment were to be performed exactly this way, how would one determine the limiting reagent of the reaction for the percent yield calculation? What should be the limiting reagent of this reaction? When I ran this experiment, I was able to form 0.43 g of product.

Thanks for your help!

C-Language

Modify the existing vector's contents, by erasing 200, then inserting 100 and 102 in the shown locations. Use Vector ADT's erase() and insert() only. Sample output of below program:

100 101 102 103 

----------------------------------------------------------------------------------

#include <stdio.h>
#include <stdlib.h>

// struct and typedef declaration for Vector ADT
typedef struct vector_struct {
   int* elements;
   unsigned int size;
} vector;

// Initialize vector with specified size
void vector_create(vector* v, unsigned int vectorSize) {
   int i;

   if (v == NULL) return;

   v->elements = (int*)malloc(vectorSize * sizeof(int));
   v->size = vectorSize;
   for (i = 0; i < v->size; ++i) {
      v->elements[i] = 0;
   }
}

// Resize the size of the vector
void vector_resize(vector* v, unsigned int vectorSize) {
   int oldSize;
   int i;
   if (v == NULL) return;

   oldSize = v->size;
   v->elements = (int*)realloc(v->elements, vectorSize * sizeof(int));
   v->size = vectorSize;
   for (i = oldSize; i < v->size; ++i) {
      v->elements[i] = 0;
   }
}

// Return pointer to element at specified index
int* vector_at(vector* v, unsigned int index) {
   if (v == NULL || index >= v->size) return NULL;

   return &(v->elements[index]);
}

// Insert new value at specified index
void vector_insert(vector* v, unsigned int index, int value) {
   int i;

   if (v == NULL || index > v->size) return;

   vector_resize(v, v->size + 1);
   for (i = v->size - 1; i > index; --i) {
      v->elements[i] = v->elements[i-1];
   }
   v->elements[index] = value;
}

// Insert new value at end of vector
void vector_push_back(vector* v, int value) {
   vector_insert(v, v->size, value);
}

// Erase (remove) value at specified index
void vector_erase(vector* v, unsigned int index) {
   int i;

   if (v == NULL || index >= v->size) return;

   for (i = index; i < v->size - 1; ++i) {
      v->elements[i] = v->elements[i+1];
   }
   vector_resize(v, v->size - 1);
}

// Return number of elements within vector
int vector_size(vector* v) {
   if (v == NULL) return -1;

   return v->size;
}

void PrintVectors(vector* numberList) {
   int i;

   for (i = 0; i < vector_size(numberList); ++i) {
      printf("%d ", *vector_at(numberList, i));
   }
   printf("\n");
}

int main(void) {
   vector numberList;
   vector_create(&numberList, 0);

   // Populate vector with 101 200 103
   vector_push_back(&numberList, 101);
   vector_push_back(&numberList, 200);
   vector_push_back(&numberList, 103);

   // Erase 200 then insert 100 and 102

   /* Your solution goes here */

   PrintVectors(&numberList);

   return 0;
}

1) Consider the reaction:

A (aq) ⇌ B (aq)

at 253 K where the initial concentration of A = 1.00 M and the initial concentration of B = 0.000 M. At equilibrium it is found that the concentration of B = 0.523 M. What is the maximum amount of work that can be done by this system when the concentration of A = 0.859 M?

2) Consider the following reaction at 257 K:

2 A (aq) + 1 B (aq) → 2 C (aq) + 2 D (aq)

An experiment was performed with the following intitial concentrations: [A]_i = 1.37 M, [B]_i = 2.19 M, [C]_i = 0.47 M, [D]_i = 0.31 M. The reaction was allowed to proceed until equilibrium was reached at which time it was determined that [A] = 0.57 M. What is ΔG_nonstandard at the initial conditions? (I got -14.16kJ but it said i was wrong)

3) Consider the cell described below at 287 K:

Sn | Sn²⁺ (1.27 M) || Pb²⁺ (2.49 M) | Pb

Given E^o_{Pb²⁺ + 2 e^-→Pb} = -0.131 V and E^o_{Sn²⁺ + 2 e^-→Sn} = -0.143 V. What will the concentration of the Pb²⁺ solution be when the cell is dead?

4)A concentration cell is built based on the reaction:

2 H⁺ + 2 e^- → H₂

The pH in one of the half cells is -0.03743, while the pH in the other is 2.804. If the temperature of the overall cell is 296 K, what is the potential? (Faraday's constant is 96,485 C/mol e^-)

If V is a linear space and S is a proper subset of V, and we define a relation on V via v1 ~ v2 iff v1 - v2 are in S, a subspace of V. We are given ~ is an equivalence relation, show that the set of equivalence classes, V/S, is a vector space as well, where the typical element of V/S is v + s, where v is any element of V.

(a).    Check

<u,v> =2u1v1+3u2v2+u3v3

is inner product space or not.

If yes assume u= (8,0,-8) & v= (8,3,16)

Find

1. ||u||
2. ||v||
3. |<u, v>|²
4. Unit vector in direction of u and v
5. Distance (u, v)
6. Angle between u and v
7. Orthogonal vectors of u and v.

(b).    Show that

<u,v> =u1v1-2u2v2+u3v3

1. Describe the purpose of diffusion experiment.
2. Describe the purpose of osmosis experiment.
3. Describe the observation/results of the osmosis experiment.

1. In two different experiments exactly 5 grams of fuel burns (combusts). The first experiment is under constant pressure conditions, and the second separate experiment is under constant volume conditions.

1. Which experiment is in a coffee cup calorimeter? And which is in a bomb calorimeter?
2. One experiment produces 25 kJ of heat and one experiment produces 23 kJ of heat. Which experiment (the constant pressure one or the constant volume one) produces 25 kJ of heat and which produces 23 kJ of heat? Why?
   
   Please type the answers, don't write them on a paper

A double slit experiment is conducted with a red laser with wavelength l = 700 nm. The distance between the slits and the viewing screen is L = 2.00 m. Consider two experiments that have different slit spacings: Experiment A with dA = 2.00 μm and Experiment B with dB = 40.0 μm. For each experiment, calculate the following (be sure to keep at least three significant figures in all your intermediate calculations):

a)

1. Using Δr = d sinθ , calculate the angle, q1, for the first maximum (constructive interference) above the central maximum. Experiment A and Experiment B

b)

1. Using the angle you calculated in part a) and y = L tanθ , calculate y1, the location on the screen of the first maximum.Experiment A and Experiment B