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stiks02 [169]
3 years ago
15

Calculate the mass of 20.0 moles of He (in g)

Chemistry
1 answer:
Daniel [21]3 years ago
7 0

Explanation:

20.0 moles= 80.1 or 80.05g

5.00 moles= 20.0g

1.20×1025moles= 4923.2g

1.00 moles= 4.00g

80.0 moles= 320.2g

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When atoms are heated, what is also changing?
Norma-Jean [14]
The end result of increased molecular motion is that the object expands and takes up more space. {I don’t know if it’s right, I‘m just trying to help}
7 0
3 years ago
Read 2 more answers
I want to know the steps.
Artyom0805 [142]

The answer for the following problem is described below.

<em><u> Therefore the standard enthalpy of combustion is -2800 kJ</u></em>

Explanation:

Given:

enthalpy of combustion of glucose(ΔH_{f} of C_{6}H_{12} O_{6}) =-1275.0

enthalpy of combustion of oxygen(ΔH_{f} of O_{2}) = zero

enthalpy of combustion of carbon dioxide(ΔH_{f} of CO_{2}) = -393.5

enthalpy of combustion of water(ΔH_{f} of H_{2} O) = -285.8

To solve :

standard enthalpy of combustion

We know;

ΔH_{f}  = ∈ΔH_{f} (products) - ∈ΔH_{f} (reactants)

C_{6}H_{12} O_{6} (s) +6 O_{2}(g) → 6 CO_{2} (g)+ 6 H_{2} O(l)

ΔH_{f} = [6 (-393.5) + 6(-285.8)] - [6 (0) + (-1275)]

ΔH_{f} = [6 (-393.5) + 6(-285.8)] - [0 - 1275]

ΔH_{f} = 6 (-393.5) + 6(-285.8)  - 0 + 1275

ΔH_{f} = -2361 - 1714 - 0 + 1275

ΔH_{f} =-2800 kJ

<em><u> Therefore the standard enthalpy of combustion is -2800 kJ</u></em>

7 0
3 years ago
Match the events related to the formation of the universe with the stages in which they occurred
Ira Lisetskai [31]

Answer : The chronological order events related to the formation of the universe with the stages in which they occurred are given below;

  1. Expansion from an infinitely hot point  - Which is also called as the Planck era from which the big bang theory arrived. It is assumed that from the moment of initial expansion to 10^{-43} seconds afterwards, and many also refer that it was from an infinitely hot point.
  2. Hydrogen fuses into helium  - This was called as the era of Nucleosynthesis which resulted from the Fusion and it continued in the Era of Nucleosynthesis ( which is 0.001 seconds – 3 minutes)
  3. The first neutral atom begins to form - Era of atoms, it began in around 380,000 years – 1 billion years or so.

For better understanding please refer the attachment.

3 0
4 years ago
Calculate the number of hydrogen atoms in a sample of hydrazine . Be sure your answer has a unit symbol if necessary, and round
gladu [14]

Answer:

atoms \ H= 9.767x10^{24}atoms

Explanation:

Hello!

In this case, considering that the mass of hydrazine is missing, we can assume it is 130.0 g (a problem found on ethernet). In such a way, since we need a mass-mole-atoms relationship by which we can compute moles of hydrazine given its molar mass (32.06 g/mol), then the moles of hydrogen considering one mole of hydrazine has four moles of hydrogen and one mole of hydrogen has 6.022x10²³ atoms (Avogadro's number); therefore, we proceed as shown below:

atoms \ H=130.0gN_2H_4*\frac{1molN_2H_4}{32.06gN_2H_4} *\frac{4molH}{1molN_2H_4} *\frac{6.022x10^{23}atoms}{1molH}\\\\atoms \ H= 9.767x10^{24}atoms

Notice 130.0 g has four significant figures, therefore the result is displayed with four as well.

Best regards!

7 0
3 years ago
1. Metallic strontium crystallizes in a face-centered cubic lattice, with one Sr atom per lattice point. If the edge length of t
Zarrin [17]

Answer:

r=215pm

N_{Mn}=20

Explanation:

From the question we are told that:

Edge length of the unit cell l=608pm

a)

Generally the equation for The relationship between edge length and radius is mathematically given by

4r=\sqrt{2a}

Therefore

4r=\sqrt{2*608}

r=\frac{\sqrt{2*608}}{4}

r=215pm

b)

From the question we are told that:

Density \rho=7.297

Edge length of l=630.0 pm=>630*10^-{10}

Therefore Volume  is given as

V=l^3

V=630*10^-{10}^3

V=2.50047*10^{−22}

Generally the equation for Mass is mathematically given by

m=Volume*density

m=V*\rho

m=2.50047*10^{−22}*7.297

m=1.83*10^{-21}g

Therefore Molarity is given as

n=\frac{M}{Molar M}

n=\frac{1.83*10^{-21}g}{55}

n=3.32*10^{-23}

Finally The atoms in a unit cell is

N_{Mn}=Moles*Avogadro\ constant

N_{Mn}=3.32*10^{-23}*6.023*10^{23}

N_{Mn}=20

7 0
3 years ago
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