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pychu [463]
3 years ago
5

I NEED HELP FAST!!!!! Can you tell me about the development of the periodic table??? I have a DBA in a few minutes and I don't k

now!!! Please use easy to understand answers 'cause I'm a little under the weather.
Chemistry
1 answer:
weqwewe [10]3 years ago
5 0
Dimitri Mendeleev was the first to put elements together on a table. He knew there were elements missing but he noticed a trend in some of the elements known at the time. Sodium, Lithium and other alkali metals all have the same properties so he put them under the same column and created other columns with similar attributes (Halogens, Noble gases, Alkaline earth metals). Over the years, new elements were discovered and put into the rough outline that Mendeleev created.

I hope that is about what you wanted. 
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PLEASE HELP!?!.!,! What are the products of the combustion of a hydrocarbon?
Tatiana [17]

Answer:

carbon dioxide and water

Explanation:

Example: Combustion of Methane (CH₄(g))

CH₄(g) + 2O₂(g) => CO₂(g) + 2H₂O(g)**

____________________

Note: The combustion of any hydrocarbon produces CO₂ & H₂O. That is,

Ethane (C₂H₆) + O₂ => CO₂(g) + H₂O(g)

Propane (C₃H₈) + O₂ => CO₂(g) + H₂O(g)

Butane (C₄H₁₀) + O₂ => CO₂(g) + H₂O(g)

The issue remaining is to balance the reaction equation. For these type equation balance Carbon 1st, then Hydrogen and finish with Oxygen. Balancing in this order leaves Oxygen which can be balanced using fractions. If problem requires lowest whole number ratios of elements, simply multiply entire equation by 2 to get standard equation*

______________________

*Standard Equation is defined as the smallest whole number ratios of elements. The 'standard equation' is significant in that it is assumed to be at STP conditions; i.e., 0⁰C (=273K) & 1.0 Atmosphere pressure.

  • Ethane (C₂H₆) + 7/2O₂(g) => 2CO₂(g) + 3H₂O(g)

    => 2C₂H₆ + 7O₂(g) => 4CO₂(g) + 6H₂O(g)  <= Standard Form of Rxn

  • Propane (C₃H₈) + 5O₂(g) => 3CO₂(g) + 4H₂O(g) <= Standard Form of Rxn (no need to balance with the '2' multiple)
  • Butane (C₄H₁₀) + 13/2O₂ => 4CO₂(g) + 5H₂O(g)

    => 2C₃H₈ + 13O₂(g) => 4CO₂(g) + 5H₂O(g) <= Standard Form of Rxn

______________________

**Also, note that water, H₂O(g), is listed as a gas. In some cases it will be listed as a liquid, H₂O(l).

3 0
3 years ago
Read 2 more answers
How does raising the temperature affect the rate of reaction
Vesnalui [34]
<span>The rate of a chemical reaction can be increased by raising the temperature. </span>
4 0
3 years ago
Identify each of the following solids as molecular, ionic, or atomic.
Kisachek [45]

Answer :

(A) Br₂ (s) : molecular solids

(B) AgCl (s) : ionic solids

(C) S (s) : atomic solids

(D) CH₄ (s) : molecular solids

Explanation :

Molecular solids : It is defined as the solids in which they are held together by covalent forces, dipole interactions as attractive forces etc.

Ionic solids : It is defined as the solids in which the atoms composed with oppositely charged ions.

Atomic solids : It is defined as the solids in which the molecules are held together by covalent forces and also includes pure substance.

(A) Br₂ (s)

It is molecular solids because they are held together by covalent forces.

(B) AgCl (s)

It is ionic solids because in this atoms composed with oppositely charged ions.

(C) S (s)

It is atomic solids because it is a pure substance.

(D) CH₄ (s)

It is molecular solids because they are held together by covalent forces.

7 0
3 years ago
Plz help me asap i need this plz
Arturiano [62]
I think it’s because from earth things may appear smaller smaller in space where in actuality in space it can be way larger
6 0
2 years ago
Iron (III) oxide and hydrogen react to form iron and water, like this: Fe 03(s)+3H9)2Fe(s)+3HO) At a certain temperature, a chem
belka [17]

The question is incomplete, here is the complete question:

Iron (III) oxide and hydrogen react to form iron and water, like this:

Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)

At a certain temperature, a chemist finds that a 8.9 L reaction vessel containing a mixture of iron(III) oxide, hydrogen, Iron, and water at equilibrium has the following composition.

Compound             Amount

  Fe₂O₃                     3.95 g

     H₂                        4.77 g

     Fe                        4.38 g

    H₂O                      2.00 g

Calculate the value of the equilibrium constant Kc for this reaction. Round your answer to 2 significant digits.

<u>Answer:</u> The value of equilibrium constant for given equation is 1.0\times 10^{-4}

<u>Explanation:</u>

To calculate the molarity of solution, we use the equation:

\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}

  • <u>For hydrogen gas:</u>

Given mass of hydrogen gas = 4.77 g

Molar mass of hydrogen gas = 2 g/mol

Volume of the solution = 8.9 L

Putting values in above expression, we get:

\text{Molarity of hydrogen gas}=\frac{4.77}{2\times 8.9}\\\\\text{Molarity of hydrogen gas}=0.268M

  • <u>For water:</u>

Given mass of water = 2.00 g

Molar mass of water = 18 g/mol

Volume of the solution = 8.9 L

Putting values in above expression, we get:

\text{Molarity of water}=\frac{2.00}{18\times 8.9}\\\\\text{Molarity of water}=0.0125M

For the given chemical equation:

Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)

The expression of equilibrium constant for above equation follows:

K_{eq}=\frac{[H_2O]^3}{[H_2]^3}

Concentration of pure solids and pure liquids are taken as 1 in equilibrium constant expression.

Putting values in above expression, we get:

K_{c}=\frac{(0.0125)^3}{(0.268)^3}\\\\K_{c}=1.0\times 10^{-4}

Hence, the value of equilibrium constant for given equation is 1.0\times 10^{-4}

6 0
3 years ago
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