Approximately _____ elements occur naturally on earth.

Mrs. Stark weighs 70kg. How much Potential Energy does she have if she stands on the roof of an 80m tall building?

8_murik_8 [283]

E = mgh

E = 70*9.81*80

E = 54936 J

5 0

3 years ago

Describe how elements are laid out on the periodic table of elements.

defon

Answer:

The chemical elements are arranged in order of increasing atomic number.

Explanation:

Hydrogen = 1

Helium = 2

Lithium = 3

8 0

3 years ago

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Atoms full valence electron shells are chemically stable. Most noble gases have eight valence electrons. So, one bottle for chem

kap26 [50]

Gain or lose.
The exchange of electrons in chemical bonding seeks to fulfill the octet rule. There are some exceptions, such as with hydrogen and helium, whose valence shells have a capacity of two electrons.

6 0

3 years ago

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The powder mixture (Cu, Al and Fe) = 10g was oxidized from sufficient chloride acid. 1) What are the possible reactions to the p

Mandarinka [93]

Answer:

1) 2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

Fe + 2HCl ⟶ FeCl₂ + H₂

2) Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g

Explanation:

1) Possible reactions

2Al + 6HCl ⟶ 2AlCl₃ + 3H₂

Fe + 2HCl ⟶ FeCl₂ + H₂

2) Mass of each metal

a) Mass of Cu

The waste was the unreacted copper.

Mass of Cu = 2.5 g

b) Masses of Al and Fe

We have two relations :

Mass of Al + mass of Fe = 10 g - 2.5 g = 7.5 g

H₂ from Al + H₂ from Fe = 6.38 L at NTP

i) Calculate the moles of H₂

NTP is 20 °C and 1 atm.

$\begin{array}{rcl}pV & = & n RT\\\text{1 atm} \times \text{6.38 L} & = & n \times 0.08206 \text{ L}\cdot\text{atm}\cdot\text{K}^{-1}\text{mol}^{-1} \times \text{293.15 K}\\6.38 & = & 24.06n \text{ mol}^{-1} \\n & = & \dfrac{6.38}{24.06 \text{ mol}^{-1} }\\\\ & = & \text{0.2652 mol}\\\end{array}$

(ii) Solve the relationship

Let x = mass of Al. Then

7.5 - x = mass of Fe

Moles of Al = x/27

Moles of Fe = (7.5 - x)/56

Moles of H₂ from Al = (3/2) × Moles of Al = (3/2) × (x/27) = x /18

Moles of H₂ from Fe = (1/1) × Moles of Fe = (7.5 - x)/56

∴ x/18 + (7.5 - x)/56 = 0.2652

56x + 18(7.5 - x) = 267.3

56x + 135 - 18x = 267.3

38x = 132.3

x = 3.5 g

Mass of Al = 3.5 g

Mass of Fe = 7.5 g - 3.5 g = 4.0 g

The masses of the metals are Cu = 2.5 g; Al = 3.5 g; Fe = 4.0 g

4 0

3 years ago

Brainiest if correctly answered in 5m

erastovalidia [21]

I will list them from alkaline with the lowest boiling point and alkaline with the highest.

1. C2H6
2. C9H20
3. C11H24
4. C16H34
5. C20H42
6. C32H66
7. C150H302

I have taken a quiz similar to this before and can assure you this is correct and is primarily because of the number of Carbons and Hydrogens within this. More Carbons and Hydrogens causes Boiling Points to increase because of stronger bonds.

8 0

3 years ago