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3 years ago

How were the atomic models developed given that no one had seen an atom

Chemistry

1 answer:

AysviL [449]3 years ago

6 0

They were noticed through the first mircoscope

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Three isotopes of argon occur in nature – 36 18Ar, 38 18Ar, 40 18Ar. Calculate the average atomic mass of argon to two decimal p

likoan [24]

Answer: 3) 39.96 amu

Explanation:

Mass of isotope Ar- 36 = 35.97 amu

% abundance of isotope Ar- 36= 0.337% = $\frac{0.337}{100}=3.37\times 10^{-3}$

Mass of isotope Ar- 38 = 37.96 amu

% abundance of isotope 2 = 0.063 % = $\frac{0.063}{100}=6.3\times 10^{-4}$

Mass of isotope Ar- 40 = 39.96 amu

% abundance of isotope 2 = 99.600 % = $\frac{99.600}{100}=0.996$

Formula used for average atomic mass of an element :

$\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})$

$A=\sum[(35.97\times 3.37\times 10^{-3})+(37.96\times 6.3\times 10^{-4})+(39.96\times 0.996)]$

$A=39.96amu$

Therefore, the average atomic mass of argon is 39.96 amu

4 0

4 years ago

The process where a substance reacts with oxygen

daser333 [38]

Answer:

The process where substance react with oxygen is called combustion.

Explanation:

When substance react with oxygen combustion is occur. The substance which burned is called fuel and in this process large amount of heat is released to the surrounding. It is exothermic process.

For example:

4Li + O₂ → 2Li₂O

2Mg + O₂ → 2MgO

S + O₂ → SO₂

The product which is formed as a result of combustion reaction are called oxides.

In given examples we can see that lithium, magnesium and sulfur react with oxygen and product formed is oxides of respective elements such as lithium oxide ( Li₂O), magnesium oxide (MgO) and sulfur oxide ( SO₂ ).

3 0

4 years ago

Question 14 A student dissolves 1.5g of styrene C8H8 in 225.mL of a solvent with a density of 1.02/gmL . The student notices tha

Yuki888 [10]

We must to know:

Cm = molarity = niu / Vs, when the niu = no. of moles and Vs = Volume of solution

the no. niu = mass / molecular mass of substance

molecular mass of C8H8 = 12x8+8x1 = 104 g/mol

=> niu = 1,5 / 104 = 0,0144 moles C8H8

=> Cm = 0,0144/0,225 = 0,06 mol/L

Cmm = molality = niu (C8H8) / mass of solvent (kg)

=> p = mass / V => mass (solvent) = p x V

=> 225 x 1,02 = 229,5 g solvent = 0,2295 kg solvent

=> Cmm = 0,0144 / 0,229,5 = 0,063

8 0

3 years ago

Read 2 more answers

Use the Lab Report document as a template. Use the descriptions and examples of each part to help you write your Lab Report. You

GarryVolchara [31]

This link might help you!!

https://www.eiu.edu/biology/bio1500/writing_a_lab_report.pdf

6 0

3 years ago

12. Photosynthesis builds sugars out of small molecules, making it an

JulsSmile [24]

Answer:

Condensation reaction/ direct synthesis reaction

Explanation:

Combines simple molecules to form complex molecules producing water

8 0

3 years ago