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Oxana [17]

A Timeline on Atomic Structure. 400 B.C. Democritus' atomic theory posited that all matter is made up small indestructible units he called atoms. ... 1803 John Dalton proposed that elements consisted of atoms that were identical and had the same mass and that compounds were atoms from different elements combined together.

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3 years ago

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Stoichiometry is best defined as the

Oxana [17]

Stoichiometry is “quantitative relationship” among the “reactants” and the “products” in a “chemical reaction”.

Explanation:

In stoichiometry “stoicheion” means element and “metron” means measure in Greek. The stoichiometric calculation depends upon “stoichiometric coefficients” in a “chemical equation” which can be explained as the “number of moles” of each substance (reactants or products). Stoichiometric calculation is done as follows:

For example reaction between nitrogen and hydrogen to form ammonia as

$\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{g})$

Here stoichiometric coefficients show that “one molecule of nitrogen” reacts with “three molecules of hydrogen” to form “two molecules of ammonia”. Multiplying Avogadro number $6.022 \times 10^{23}$ to no of molecules in equation:

$\text { For } \mathrm{N}_{2}: 1 \times 6.022 \times 10^{23}=1 \mathrm{mol}$

$\text { For } 3 \mathrm{H}_{2}: 3 \times 6.022 \times 10^{23}=3 \mathrm{mol}$

$\text { For } 2 \mathrm{NH}_{3}: 2 \times 6.022 \times 10^{23}=2 \mathrm{mol}$

Taking molar masses into consideration:

$\text { For } \mathrm{N}_{2}: 1 \times 28.0=28.0 \mathrm{gm}$

$\text { For } 3 \mathrm{H}_{2}: 3 \times 2=6.0 \mathrm{gm}$

$\text { For } 2 \mathrm{NH}_{3}: 2 \times 17=34 \mathrm{gm}$

Hence balanced equation gives stoichiometric coefficients which gives proportion by moles.

8 0

3 years ago

A thermometer with a percent error of 6.5% reads the room temperature as 68°F. what is the actual temperature in the room ?

Lynna [10]

Answer:

Actual temperature for the given temperature with thermometer with error of 6.5% is 63.8 degrees.

Explanation:

The percentage error in thermometer is 6.5% this means that if the temperature is 100 degrees the thermometer shell show 106.5 degrees. now calculating the actual temperature of the thermometer when the given temperature is 68°

Applying unitary method for solution 106.5

Then 100 will be $\frac {68}{106.5} \times 100$

= $0.6384 \times 100$

= 63.8 Degrees

On solving the value of this equation will give the actual temperature as 63.8 Degrees .

5 0

3 years ago

PLEASE HELP ME I WILL MARK AS BRAINLIEST ANSWER-100 points

hammer [34]

Answer:

4:Chlorophyll. 6. Photosynthesis 8. Glucose

Explanation:

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3 years ago

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What does the foundation of the continents mostly consist of?

Dafna11 [192]

Answer:

The correct answer is sedimentary rock.

Explanation:

The sedimentary rocks are the types of rocks, which are produced due to the deposition and the succeeding cementation of that substance at the shallow part of the Earth and within the water bodies. In the geological sciences, sedimentation refers to the procedure of the deposition of the solid substance from a state of solution or suspension in a fluid, that is, water or air.

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3 years ago

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