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3 years ago

An atom has the following electron configuration.

Chemistry

2 answers:

vagabundo [1.1K]3 years ago

8 0

Answer: The number of valence electron in the given atom are 5

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of an atom. Outermost shell has the highest value of 'n' that is principal quantum number.

For the given electronic configuration: $1s^22s^22p^63s^23p^64s^23d^3$

When an element belongs to d-block, the number of valence electrons are present in $ns,np\text{ and }(n-1)d$ orbitals

Here, n = 4

The electrons in '4s' orbital = 2

The electrons in '3d' orbital = 3

Number of valence electrons = 2 + 3 = 5

Hence, the number of valence electron in the given atom are 5

V125BC [204]3 years ago

3 0

Answer:

Explanation:

The valence electrons are the electrons that are located in the outermost shel of an atom.

Writing the configuration properly, we have:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³

In this atom, there is a total number of 23 electrons. This is a transition metal.

The 4s and 3d orbitals are in the outermost energy levels and so their electrons are valent.

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Ethanol (c2h5oh) melts at -114Â°c. the enthalpy of fusion is 5.02 kj/mol. the specific heats of solid and liquid ethanol are 0.9

Nimfa-mama [501]

Answer: 4.18925 kJ heat is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

Explanation:

Temperature of Solid $C_2H_5OH=-135^oC=138 K(0^oC=273K)$

Melting temperature of Solid $C_2H_5OH=114^oC=159 K$

Temperature of liquid $C_2H_5OH=-50^oC=223K$

Specific heats of solid ethanol = 0.97 J/gK

Specific heats of liquid ethanol = 2.3 J/gK

Heat required to melt the the 25 g solid $C_2H_5OH$ at 159 K

$\Delta T_1$ = 159 K - 138 K = 21 K

$Q_1=mc\Delta T= 25\times 0.97J/gK\times 21 K=509.25 J$

Heat required to melt and raise the temperature of $C_2H_5OH$ upto 223 K

$\Delta T_2$ = 223 K - 159 K = 64 K

$Q_2=mc\Delta T= 25\times 2.3J/gK\times 64 K=3680 J$

Total heat to convert solid ethanol to liquid ethanol at given temperature :

$Q_1+Q_2=509.25 J+3680 J=4189.25 J=4.18925 kJ$ (1kJ=1000J)

Hence, 4.18925 kJ of heat will be required to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

6 0

3 years ago

One type of electromagnetic radiation that could harm humans

Vladimir79 [104]

Ultraviolet Rays ( UV rays) can harm humans because they can cause sunburn, and skin cance if you stay out in the sun for too long.

3 0

3 years ago

O tetraclorometano é um solvente muito utilizado na indústria de transformaç?o de produtos orgânicos ele é produzido pela reaç?o

Vlada [557]

Answer:

ΔHr = -103,4 kcal/mol

Explanation:

Using:

AH° (kcal/mol)

Metano (CH)

-17,9

Cloro (CI)

tetraclorometano (CCI)

- 33,3

Acido cloridrico (HCI)

-22

It is possible to obtain the ΔH of a reaction from ΔH's of formation for each compound, thus:

ΔHr = (ΔH products - ΔH reactants)

For the reaction:

CH₄(g) + Cl₂(g) → CCl₄(g) + HCl(g)

The balanced reaction is:

CH₄(g) + 4Cl₂(g) → CCl₄(g) + 4HCl(g)

The ΔH's of formation for these compounds are:

ΔH CH₄(g): -17,9 kcal/mol

ΔH Cl₂(g): 0 kcal/mol

ΔH CCl₄(g): -33,3 kcal/mol

ΔH HCl(g): -22 kcal/mol

The ΔHr is:

-33,3 kcal/mol × 1 mol + -22 kcal/mol× 4 mol - (-17,9 kcal/mol × 1 mol + 0kcal/mol × 4mol)

ΔHr = -103,4 kcal/mol

I hope it helps!

3 0

3 years ago

What mass of Cu(s) is electroplated by running 24.5A of current through a Cu2+(aq)solution for 4.00 h?Express your answer to thr

Masja [62]

Answer: 116 g of copper

Explanation:

$Q=I\times t$

where Q= quantity of electricity in coloumbs

I = current in amperes = 24.5A

t= time in seconds = 4.00 hr = $4.00\times 3600s=14400s$ (1hr=3600s)

$Q=24.5A\times 14400s=352800C$

$Cu^{2+}+2e^-\rightarrow Cu$

$2\times 96500C=193000C$ of electricity deposits 63.5 g of copper.

352800 C of electricity deposits = $\frac{63.5}{193000}\times 352800=116g$ of copper.

Thus 116 g of Cu(s) is electroplated by running 24.5A of current

Thus remaining in solution = (0.1-0.003)=0.097moles

8 0

3 years ago

What volume (in liters) does 3.91 moles of nitrogen gas at 5.35 atm and 323 K occupy

daser333 [38]

Moles = n = 3.91 mol

Pressure = P = 5.35 atm

Temperature = T = 323 K

Volume = V = ?

Formula used: Ideal Gas Equation is used,

P V = n R T
Solving for V,
V = n R T / P
Putting Values,
V = (3.91 mol × 0.0825 atm.L.mol⁻¹.K⁻¹ × 323 K) ÷ 5.35 atm

V = 19.36 L

5 0

3 years ago