Chemistry, 30.11.2020 18:30 mkidgellmas1284

A solution is prepared by dissolving 74.2 g NaI in 527 g of water. Determine the mole fraction of NaI if the final volume of the solution is 565 mL. a. 8.84 times 10^-2
b. 1.40 times 10^-3
c. 6.04 times 10^-3
d. 1.32 times 10^-2
e. 1.65 times 10^-2

Answers: 3

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Answers

Answer from: paco38

The correct answer is option e, that is, 1.65 * 10^-2.

Explanation:

Based on the given information, the weight of NaI given is 74.2 grams and the weight of water given is 527 grams.

The final volume of the solution given is 566 ml.

The formula to calculate the moles is weight/molecular mass,

The moles of NaI will be,

= 74.2/150 = 0.494

Now moles of water will be,

= 527/18 = 29.3

The mole fraction of NaI will be,

= 0.494 / (0.494 + 29.3)

= 0.0165 or 1.65 * 10^-2

Hence, the mole fraction of NaI is 1.65 * 10^-2

Answer from: Quest

the mass of the cathode increases because ions from the solution get reduced to atoms and become part of the cathode.

explanation:

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Answer from: Quest

assuming that your periodic table has eighteen columns, you should highlight the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the $3d$ have energy higher than those in the $4 s$ orbital while lower than those of the $4 p$ orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the $4s$ orbital is therefore filled right after $3p$ orbitals and before $3 d$ orbitals.

potassium has electron configuration $[\text{ar}] 4 s^{1}$ and calcium $[\text{ar}] 4 s^{2}$ . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration $[\text{ar}] 4 s^{2} \; 3d^{1}$ and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the $ns^{2} \; (n-1) p^{1}$ and should be highlighted as well.

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