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Y_Kistochka [10]
3 years ago
6

Which enthalpy change (î"h) is correct for a substance changing from the liquid phase to the solid phase?

Chemistry
1 answer:
Mnenie [13.5K]3 years ago
7 0
I believe this should be the enthalpy of fusion. Enthalpy change is the amount of heat evolved or absorbed in a reaction. Enthalpy of fusion also called the heat of fusion resulting from providing heat energy or release of energy to a specific amount of a substance to change from solid state to liquid, without change in temperature.
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The quantum numbers for the last electron placed in three elements are listed below. Which of these is(are) NOT correct? Er (4 3
UNO [17]

Answer:

The three elements Erbium, Thallium and Osmium have incorrect quantum numbers for the last electron placed.

Explanation:

The 4 quantum numbers are (<em>n,l,ml,ms</em>):

  • <em>n</em> (Principal quantum number): it is the <u>number of the shell (level)</u> where the electron is placed.
  • <em>l </em>(Angular momentum quantum number or Secondary): it represents the <u>sublevel where the electron is</u> placed. There are 4 subleves: s, p d and f so secondary quantum number can take the number 0 (s), 1 (p), 2 (d) or 3 (f) depending on which sublevel the electron is placed.
  • <em>ml</em> (Magnetic quantum number):  it represents the <u>spatial orientation</u> of the electron <u>in respect of the sublevel the electron</u> is placed. For example: if the electron occupies the <em>s sublevel</em> the magnetic number will be <em>0</em>, if the electron occupies the <em>p sublevel</em> the magnetic number could be <em>-1,0,1</em>, if the electron occupies the <em>d sublevel</em> the magnetic number could be <em>-2,-1,0,1,2</em> and if the electron occupies the <em>f sublevel</em> the magnetic number could be <em>-3,-2,-1,0,1,2,3</em>. You can see this in the attachment related to the correct sublevel for the example.
  • <em>ms</em> (Spin quantum number): this number represents the possible rotation of the electron so it could be 1/2 (which is represented by an up arrow) or -1/2 (represented by an down arrow).

Let's analyze the last electron of each element. You can see the attachment for better understanding. The last electron it is represented with orange color.

- Erbium:

This element has 68 electrons so following the Moeller's Diagram to fill the the electronic configuration, we found that the last electron of Erbium it is in the <u>4th level </u>(shell), in the <u>f sublevel</u>. As Erbium has 12 electrons in the f sublevel, it is necessary to follow the Hund's rule (electrons must be placed singly in every sublevel before place a parallel electron) to placed correctly all of them. Finally, the last electron of Erbium stays in the middle of the sublevel and it is represented by a down arrow so the correct quantum numbers in the Erbium element are (4,3,1,-1/2).

- Thallium:

This element has 81 electrons and following the Moeller's Diagram, we found that it last electron it is in the <u>6th level</u>, in the <u>p sublevel</u>. As Thallium has 1 electron in the p sublevel, it is placed singly in the sublevel. So the last electron of Thallium it is represented by an up arrow so the correct quantum numbers in the Thallium element are (6,1,-1,1/2).

- Osmium:

Osmium has 76 electrons and following the steps  that we did with we the other elements, we noticed that its last electron it is in the <u>5th level</u>, in the <u>d sublevel</u>. Following the Hund's rule the last electron of Osmium has a magnetic quantum number of -2 and its spin quantum number is -1/2, so the quantum numbers in the Osmium element are (5,2,-2,-1/2).

<u>Note:</u>

- Remember that the <em>s sublevel</em> has place for 2 electrons, the <u>p sublevel</u> has place for 6 electrons, the <u>d sublevel</u> has place for 10 electrons and the<em> f sublevel</em> has place for 14 electrons.

3 0
3 years ago
If the length, width, and height of a box are 10.00 cm, 7.25 cm and 3.00 cm, respectively, what is the volume of the box in unit
Blizzard [7]

<u>Answer:</u>

<u>For a:</u> The volume of the box is 217.5 mL

<u>For b:</u> The volume of the box is 0.2175 L

<u>Explanation:</u>

The box is a type of cuboid.

To calculate the volume of cuboid, we use the equation:

V=lbh

where,

V = volume of cuboid

l = length of cuboid = 10.00 cm

b = breadth of cuboid = 7.25 cm

h = height of cuboid = 3.00 cm

Putting values in above equation, we get:

V=10.00\times 7.25\times 3.00=217.5cm^3

  • <u>For a:</u>

To convert the volume of cuboid into milliliters, we use the conversion factor:

1mL=1cm^3

So,

\Rightarrow 217.5cm^3\times (\frac{1mL}{1cm^3})\\\\\Rightarrow 217.5mL

Hence, the volume of the box is 217.5 mL

  • <u>For b:</u>

To convert the volume of cuboid into liters, we use the conversion factor:

1L=1000cm^3

So,

\Rightarrow 217.5cm^3\times (\frac{1L}{1000cm^3})\\\\\Rightarrow 0.2175L

Hence, the volume of the box is 0.2175 L

3 0
3 years ago
18.2L of gas at 95°C and 760 torr is placed in a 15L container at 80 degrees * C ; what is the new pressure ?
romanna [79]

Answer:

884.56 torr

Explanation:

Formula: \frac{P_{1}V_{1} }{T_{1}} = \frac{P_{2}V_{2} }{T_{2}}

P = Pressure

V = Volume

T = Temperature in kelvin (Celsius + 273.15)

\frac{(760)(18.2) }{368.15} = \frac{P(15) }{353.15}

P = \frac{(760)(18.2)(353.15) }{(368.15)(15)}

P = 884.56169

4 0
3 years ago
How do strong southerly winds affect the vapor pressure?
dedylja [7]

Answer:

An increase

Explanation:

The strong southerly winds affect the vapor pressure by increasing it .

When the vapor pressure increases it means an increase in temperature and more evaporation occurs.

A decrease in the vapor pressure means a reduction in temperature with less amount of evaporation being involved

5 0
3 years ago
In the periodic table, a set of properties repeats from
jok3333 [9.3K]

in the periodic table, a set of properties repeats from row to row

3 0
3 years ago
Read 2 more answers
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