Question

any experiment to verify the law of conservation of mass​

Answer 1

Answer:

Materials Substitutions

solutions of NaOH, CuSO4, NH4OH, and Na2CO3 solutions made with Drano, Bluestone algaecide, ammonia, and washing soda

4 graduated cylinders 4-2 oz plastic cups

3 150-mL beakers 3-5 oz plastic cups

balance  

Procedure

1. Label the four graduated cylinders (or 2 oz cups) to contain the solutions (one each for NaOH, CuSO4, NH3 (aq), and Na2CO3).

2. Use a graduated cylinder to measure about 60 mL (2 oz) of the NaOH solution. Use a second graduated cylinder to measure about 60 mL (2 oz) of the CuSO4 solution and pour it into a 150-mL beaker (or 5 oz cup).

3. Carefully place the two solutions (in their containers) on the balance. Weigh the solutions and their containers together and record their combined weight.

4. Pour the NaOH solution into the container with the CuSO4 solution. Allow the solutions to mix. Describe what happens.

5. Weigh both containers and the mixture again. Record the new weight.

Did the weight change?

6. Repeat the process in steps # 2 and #3 above, first substituting NH3 (aq.) for the NaOH solution, then substituting Na2CO3 for the NaOH solution. In each case measure and record the masses as described in steps #3 and #5 above.

Data and Observations

1. Total weight of NaOH and CuSO4: Before __________g After _______g

2. Total weight of NH3 (aq) and CuSO4: Before __________g After _______g

3. Total weight of Na2CO3 and CuSO4: Before __________g After _______g

Extensions

The substances chosen for this lab are common and easy to find. You may want to repeat this lab with solutions of Fe(NO3)2 or Zn(NO3)2 solutions with Na2CO3. or NaOH. Note that NEITHER iron(II) or zinc carbonates or hydroxides are as insoluble as the copper(II) analog. While barium and lead salts have frequently been used in this type experiment, the problems associated with disposing of these materials suggests NOT USING either of these salts in experiments.

Explanation:

Answer 2

Question-

Verify the law of conservation of mass.

Answer-

Aim

To verify the law of conservation of mass in a chemical reaction

Materials Required

Barium chloride (BaCl₂.2H₂O), sodium sulphate (Na₂SO₄.10H₂O), distilled water, two beakers (150 mL), one beaker (250 mL), physical balance, spring balance (0 - 500 g) and a polythene bag, two watch glasses of known masses and a glass stirrer.

Procedure

Step 1: 100 mL distilled water is poured in two beakers (150 mL).

Step 2: The physical balance and a watch glass of known mass are used, weigh 7.2 g of BaCl₂ .2H₂O and dissolved in a beaker (150 mL) containing 100 mL distilled water.

Step 3: Similarly, 16.1 g of Na₂SO₄.10H₂O is weighed in another watch glass of known mass and dissolved in another beaker (150 mL) containing 100 mL distilled water.

Step 4: The third beaker (250 mL) is taken and weighed using a spring balance and polythene bag.

Step 5: Both solutions of 150 mL beakers are mixed in the third beaker (250 mL). The contents are mixed using a glass stirrer.

Step 6: White precipitate of BaSO₄ appears on mixing due to precipitation reaction.

Step 7: The beaker containing the reaction mixture is weighed again to determine the mass of the precipitation reaction products.

Step 8: The masses before and after the chemical reaction are compared.

Observations

(i) Mass of 100 mL distilled water = 100.0 g (The density of distilled water is 1 g/mL.)

(ii) Mass of BaCl₂ .2H₂O = 7.2 g

(iii) Mass of BaCl₂ solution = 107.2 g

(iv) Mass of Na₂ SO₄.10H₂O = 16.1 g

(v) Mass of Na₂SO₄ solution = 116.1 g

(vi) Total Mass of reactants = 223.3 g (solutions of BaCl₂  and Na₂SO₄)

(vii) Mass of empty 250 mL beaker, m₁ = _____ g

(viii) Initial mass of reaction mixture and empty beaker (before the precipitation), m₂ = (m₁ + 223.3 g) = _____ g

(ix) Final mass of reaction mixture in the beaker after the precipitation m₃ = _____g

Results and Discussions

Compare the initial mass (m²) of the reaction mixture (before the precipitation) with the final mass (m³) of the reaction mixture (after precipitation). If the two masses are the same within reasonable limits, then the law of conservation of mass stays verified.

The verification of the law rests on accurate mass measurements in the laboratory. The chemical reaction involved is:

BaCl² + (aq) + SO₄²- (aq) ⇒ BaSO₄(S)