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2 years ago

Facts about : Melting Point

1 answer:

7 0

The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa. Wikipedia

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What must happen for an electron to return to its original energy level from a higher energy level?

attashe74 [19]

An electron should emit energy to return to its original energy level from a higher energy level.

<h3>What is an energy level?</h3>

Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found.

The electron absorbs the energy and jumps to a higher energy level. In the reverse process, emission, the electron returns to the ground state by releasing the extra energy that is absorbed.

Hence, an electron should emit energy to return to its original energy level from a higher energy level.

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2 years ago

At this pressure, how many molecules of air would there be in a 20 ∘C experimental chamber with a volume of 0.020 m3 ?

jonny [76]

Answer:

Explanation: The lowest pressure in a laboratory is 4.0×10^-11Pa

Using Ideal gas equation

PV = nRT

P= 4.0×10^-11Pa

V= 0.020m^3

T= 20+273= 293k

n=number of moles = m/A

Where m is the number of molecules and A is the Avogradro's number=6.02×10²³/mol

R=8.314J/(mol × K)

PV= m/A(RT)

4.0×10^-11 ×0.020 = m/6.02×10²³(8.314×293)

m = 4.0×10^-11×0.020×6.02×10^23 / (8.314×293)

m = 1.98×10^8 molecules

Therefore,the number of molecules is 1.98×10^8

8 0

3 years ago

Determine the molecular formulas of these compounds:

lianna [129]

The molecular formulas of the empirical ones of P₂O₅ and CH₂O are P₄O₁₀ and C₇H₁₄O₇, respectively, knowing that their molar masses are 310 and 200.18 g/mol, respectively.

<h3>1. Molecular formula of P₂O₅</h3>

We can calculate the molecular formula as follows:

$MF = n*EF$ (1)

Where:

MF: is the molecular formula

EF: is the empirical formula

n: is an integer

To calculate the integer <em>n</em>, we need to use the following equation:

$n = \frac{M}{M_{EF}}$ (2)

Where:

M: is the molar mass of P₂O₅ = 310 g/mol

$M_{EF}$ : is the molar mass of the empirical formula

The molar mass of the empirical formula of P₂O₅ is given by:

$M_{EF} = 2A_{P} + 5A_{O}$

Where:

$A_{P}$ : is the atomic weight of phosphorus = 30.974 g/mol

$A_{O}$ : is the <em>atomic weight</em> of oxygen = 15.999 g/mol

So, the <em>molar mass</em> of the <em>empirical formula</em> of P₂O₅ is:

$M_{EF} = (2*30.974 + 5*15.999) g/mol = 141.943 g/mol$

Now, we can find the integer <em>n </em>(eq 2).

$n = \frac{M}{M_{EF}} = \frac{310 \:g/mol}{141.943 \:g/mol} = 2$

Finally, after multiplying the integer <em>n</em> by the number of atoms on the empirical formula of P₂O₅, we have (eq 1):

$MF = n*EF = 2 \times P_{2}O_{5} = P_{(2 \times 2)}O_{(5 \times 2)} = P_{4}O_{10}$

Therefore, the molecular mass of P₂O₅ is P₄O₁₀.

<h3>2. Molecular formula of CH₂O </h3>

We know:

M: molar mass of CH₂O = 200.18 g/mol

To calculate the integer <em>n</em> and so the molecular mass of the molecule, we need to calculate the<em> molar mass</em> of the <em>empirical formula</em> of CH₂O.

$M_{EF} = A_{C} + 2A_{H} + A_{O} = (12.011 + 2*1.008 + 15.999) g/mol = 30.026 \:g/mol$

Now, the integer <em>n </em>is equal to (eq 2):

$n = \frac{M}{M_{EF}} = \frac{200.18 g/mol}{30.026 g/mol} \approx 7$

Finally, the molecular formula of the molecule is (eq 1):

$MF = n*EF = 7 \times CH_{2}O = C_{(1 \times 7)}H_{(2 \times 7)}O_{(1 \times 7)} = C_{7}H_{14}O_{7}$

Therefore, the molecular formula of CH₂O is C₇H₁₄O₇.

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I hope it helps you!

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3 years ago

Which statement describes the bonds in iron sulfate, FeSO4?

Feliz [49]

___

Regarding the bonds in FesO₄, Fe and S have an ionic bond, while S and O have covalent bonds.

Elements form bonds to increase their stability. The main types of bonds are:

Metallic bonds: they are formed between metals and the electrons are in a delocalized cloud.
Ionic bonds: they are formed between metals (lose electrons) and nonmetals (gain electrons)
Covalent bonds: they are formed between nonmetals, which share electrons.

Regarding the bonds in FesO₄:

Fe is a metal and S a nonmetal, thus they will form ionic bonds.
S and O are both nonmetals, thus they will form covalent bonds.

Regarding the bonds in FesO₄, Fe and S have an ionic bond, while S and O have covalent bonds.

Learn more: brainly.com/question/23882847

5 0

2 years ago

How many atoms are ln 6.31 moI of sodium sulfate

Art [367]

896.27
One mole of sodium sulfate is 143.04, so just multiply that times 6.31.
I may be wrong call me out if I am

6 0

3 years ago

Read 2 more answers