Challenge Problem: An aqueous solution contains 167 g CuSO4 in 820 mL of solution. The density of the solution is 1.195 g/mL. Ca

(a)   Write the balanced half-reactions for the overall process:

Oxidation: Se^2- (aq) → Se (s) + 2e-

Reduction: 2So3^2- (aq) + 3H2O (l) + 4e- → S2O3^2- + 6OH- (aq)

(b)   Assuming E sulfite is 0.57 V, compute E selenium:

E anode = E cathode – E cell

= -0.57 – 0.35

= -.092

Answer:

             Protons: 19

             Neutrons: 25

             Electrons: 19

Explanation:

Protons:

                   The atomic number determines the number of protons in an atom. Consequently, with Potassium's atomic number being 19, it contains 19 protons.

Neutrons:

                   The formula to find neutrons is:

                           # of Neutrons  =  Atomic Mass - # of Protons

Given:

                                Atomic Mass  =  43

                                # of Protons  =  19

Thus,

                                # of Neutrons  =  43 - 19

                                # of Neutrons  =  24

Electrons:

                                   In a neutral atom, the quantity of electrons matches that of protons. Therefore, a neutral Potassium atom with 19 protons must equally have 19 electrons.

Answer:

The adjustable legs along with the sand table.

Note: The question is incomplete. The full question is presented below.

Using Models to Address Questions Regarding Systems

Armando’s class was examining images of rivers shaped by flowing water. Most rivers appeared wide and shallow, except for one, which was narrow and deep. The students theorized that this river's narrowness and depth are due to:

• the steepness of the hill from which the water descends, or
• the diminutive size of the sand grains the water flows through.

To explore the answer to the question of why this river is so narrow and deep, Armando created the model outlined below.

Explanation:

The model constructed by Armando will facilitate addressing the question due to specific features:

1. Adjustable leg - as one theory proposed by the class suggests that the steep hill affecting the water's path could be the reason for the river's dimensions, the adjustable legs are designed to be raised or lowered to alter the slope, allowing testing of this theory.

2. Sand table - this acts as the streambed. By modifying the size of the sand grains, students can examine the second hypothesis that smaller sand grains contribute to the river's narrowness and depth.

The outcomes of their experimentation will lead them to a conclusion.

Answer: The percentage abundance for isotope is 3.09 %.

Explanation:

The average atomic mass of an element is calculated by taking the sum of the masses of all isotopes weighted by their respective natural fractional abundances.

To compute average atomic mass, the following formula is applied:

  .....(1)

From the information provided:

Let the fractional abundance for isotope be 'x'

• For isotope:

Mass of isotope = 27.9769 amu

Percentage abundance of isotope = 92.22 %

Fractional abundance for isotope = 0.9222

• For isotope:

Mass of isotope = 28.9764 amu

Percentage abundance for isotope = 4.68%

Fractional abundance of isotope = 0.0468

• For isotope:

Mass of isotope = 29.9737 amu

Fractional abundance for isotope = x

• The average atomic mass of silicon is 28.084 amu

By inserting these values into equation 1, we derive:

To convert this fractional abundance into a percentage, multiply by 100:

This shows that the percentage abundance for isotope is 3.09 %.