A clear liquid in an open container is allowed to evaporate. After three days, a solid is left in the container. Was the clear

The following Lewis diagram represents the valence electron configuration of a main-group element. This element is in group 2A A

Paraphin [41]

Answer: The symbol of the ion formed is $Ca^{2+}$

Explanation:

An ion is formed when a neutral atom looses or gains electrons.

When an atom looses electrons, it results in the formation of positive ion known as cation.
When an atom gains electrons, it results in the formation of negative ion known as anion.

Electronic configuration is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom is determined by the atomic number of that atom.

The element present in Group 2-A and in period 4 is Calcium (Ca)

Electronic configuration of Ca atom: $1s^22s^22p^63s^23p^64s^2$

This atom will loose 2 electrons to attain stable electronic configuration similar to Argon element (noble gas)

The electronic configration of $Ca^{2+}\text{ ion}=1s^22s^22p^63s^23p^6$

Hence, the symbol of the ion formed is $Ca^{2+}$

4 0

3 years ago

It is often necessary to prepare a dilute solution from a more concentrated solution rather than starting from a solid and just

valina [46]

Answer:

Take 10.0mL of your original solution and dilute it to 100.0mL and then, take 5.0mL of this solution and dilute it in another flask to 100.0mL

Explanation:

The initial solution of 0.3g of Red dye in 100mL has a concentration of:

0.3g Red dye × (1mol / 869g) = 3.4x10⁻⁴ mol Red Dye in 100mL = 0.100L:

3.4x10⁻⁴ mol / 0.1L = 3.4x10⁻³M

As you want a 1.7x10⁻⁵M solution, you need to dilute your solution:

3.4x10⁻³M / 1.7x10⁻⁵M = 200 times

Having this in mind, you must find the dilutions you must make to achieve the 200 of dilution factor (Dilution factor is how many times you dilute a solution from a concetrated form).

If you dilute the original solution taking 10.0mL to 100.0mL you dilute the solution: 100.0mL / 10.0mL = 10 times.

Now, you need to dilute this solution another 20 times to achieve the 10*20 = 200 times of dilution.

If you take 5.0mL of the last solution and dilute it to 100.0mL you are diluting the solution 100.0mL / 5.0mL = 20 times.

The dilution is:

3.4x10⁻³M × (10.0mL / 100.0mL) × (5.0mL / 100.0mL) = 1.7x10⁻⁵M

Thus, to obtain the 1.7x10⁻⁵M solutionyou need to:

<h3>Take 10.0mL of your original solution and dilute it to 100.0mL and then, take 5.0mL of this solution and dilute it in another flask to 100.0mL</h3>

8 0

3 years ago

1) ΔS depends not merely on q but on ______ . Although there are many possible paths that could take a system from its initial t

Rus_ich [418]

Answer:

1) qrev/ reversible/ has only one particular value/ regardless of;

2) 1 mol of H₂(g) at 0ºC

3) a phase change/ remains constant/ increase

Explanation:

1) The change can occur in a reversible or an irreversible process. When the change is reversible, the system and the surroundings can be restored to their original state by exactly reversing the change. In an irreversible process, that is not possible.

The entropy variation (ΔS) is calculated only in the reversible process because, in the irreversible one, it's difficult to determine it. So, ΔS depends on qrev, which is the heat for the reversible process.

There is only one reversible isothermal path between two states, that's why it's easy to calculate ΔS for it.

The value of ΔS doesn't depend on the path, but only on the initial and the final states, so ΔS has only one particular value regardless of the path taken between states.

2) The entropy is the measure of the disorganization of a system, so when the molecules are more distant and vibrating, the entropy is higher (Sgas > Sliquid > Ssolid), and when the temperature increases, the entropy decreases (ΔS = qrev/T), so 1 mol of H₂(g) at 0ºC has the greatest entropy.

3) During a phase change, for a pure substance, the temperature remains constant, until all the substance changes for the other phase. The entropy is the measure of the disorganization of a system, so when the degrees of freedom and motion of the molecules increase, the system becomes more disorganized, so the entropy increases.

4 0

3 years ago

How many unbonded pairs of electrons are found on the alanine molecule

-Dominant- [34]

Answer:

I'm hoping this helps!! it's on quizzes if you're wondering

6 0

2 years ago

What is the ph of a solution that results from mixing 25 ml of 0.15 M hcl to 25 ml of 0.52 m nh3?

BartSMP [9]

Answer:

7.00

Explanation:

When the solutions are mixed, the HCl dissociates to form the ions H+ and Cl-. The ion H+ will react with the NH3 to form NH4+. The stoichiometry for this is 1 mol of HCl to 1 mol of H+ to 1 mol of Cl-, and 1 mol of H+ to 1 mol of NH3 to 1 mol of NH4+.

First, let's find the number of moles of each one of them, multiplying the concentration by the volume:

nH+ = 0.15 M * 25 mL = 3.75 mmol

nNH3 = 0.52 M * 25 mL = 13 mmol

So, all the H+ is consumed, and the neutralization is completed, thus pH will be the pH of the solvent (water), pH = 7.00.

5 0

3 years ago