contestada

A student prepares two small beakers, adding 20.0 mL of 9.77 M H2O2 (aq) to each one. Each beaker is placed on an electronic balance. The student adds 0.10 g of MnO2 (s) to the second beaker and records the mass of each beaker and its contents at 10-second interval for one minute. For beaker 2, during the 60 second period (Mass of Beaker 1 H2O2 is 43.09 g, and Mass of Beaker 2 H2O2 MnO2 is 42.58 g), what is the number of moles of O2 produced and the mass of H2O2 that decomposed

Respuesta :

Answer:

0.01918 moles of O₂

1.30g of H₂O₂

Explanation:

The H₂O₂ is descomposed to O₂ in the presence of MnO₂

2 H₂O₂(aq) → O₂(g) + 2 H₂O(l)

In beaker 1, there is no reaction, and mass of H₂O₂ is:

0.0200L× (9.77mol / L) = 0.1954mol × (34g / mol) = 6.64g. And mass of beakers is:

43.09g - 6.64g = 36.45g

In the second beaker, mass of reaction is:

42.58g - 36.45g -0.1g of MnO₂ =

6.03g = 34X + 18Y (1)

Where X are moles of H₂O₂ and Y moles of water

Also, moles of H₂O₂ and H₂O are:

0.1954mol = X + Y (2)

Replacing (1) in (2):

6.03g = 34(0.1954-Y) + 18Y

6.03 = 6.6436 -34Y + 18Y

-0.6136 = -16Y

0.03835 = Y = moles of water

Based on the reaction, 2 moles of water are produced whereas 1 mol of Oxygen is produced. Thus, moles of oxygen are:

0.03835mol H₂O × (1mol O₂ / 2mol H₂O) = 0.01918 moles of O₂

Moles produced of H₂O are the same than moles of H₂O₂ descomposed. Thus, mass of H₂O₂ descomposed is:

0.03835mol ₓ (34g / mol) = 1.30g of H₂O₂

In this exercise we have to use the knowledge of moles to calculate the amount of mass that will be produced, in this way we find that:

0.01918 moles of O₂ in 1.30g of H₂O₂

So knowing that the decomposition equation will be formed by:

[tex]2 H_2O_2(aq) \rightarrow O_2(g) + 2 H_2O(l)[/tex]

So calculating the amount of H2O2 in the reaction, we find that:

[tex]0.0200L* (9.77mol / L) = 0.1954mol * (34g / mol) = 6.64g\\ 43.09g - 6.64g = 36.45g [/tex]

In the second beaker, mass of reaction is:

[tex]42.58g - 36.45g -0.1g \\ =6.03g = 34X + 18Y (1) [/tex]

Creating a system with the values ​​found earlier, we have:

[tex]0.1954mol = X + Y (2)\\ 6.03g = 34(0.1954-Y) + 18Y\\ 6.03 = 6.6436 -34Y + 18Y\\ -0.6136 = -16Y\\ 0.03835 = Y [/tex]

See more about moles at brainly.com/question/15209553