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3 years ago

How can you efficiently determine the number of atoms in a sample of an element?

Chemistry

1 answer:

nata0808 [166]3 years ago

3 0

Answer:

b. First determine the mass of the sample and then convert it to the number of atoms using Avogadro's number and the molar mass of the element.

Explanation:

a. First determine the mass of the sample and then convert it to the number of atoms using the molar mass of the element. FALSE. As the mass is in grams and molar mass is in g/mol. This result in the moles of each element, not its number of atoms.

b. First determine the mass of the sample and then convert it to the number of atoms using Avogadro's number and the molar mass of the element. TRUE. Mass and molar mass will result in moles of element. These moles could be converted in number of atoms using Avogadro's number that is in # atoms per mole.

c.Use atomic microscope to determine Avogadro's number, then determine the mass of the sample and convert it to the number of atoms. FALSE. An atomic microscope is not used to determine Avogadro's number.

d.Use atomic microscope to count each atom. FALSE. There is not possible to count every single atom in an element. There are more atoms in a drop of water than stars in the sky.

I hope it helps!

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Rank the following fertilizers in decreasing order of mass percentage of nitrogen:

charle [14.2K]

<h3>Answer:</h3>

NH₃ > NH₄NO₃ > (NH₄)₂HPO₄ > (NH₄)₂SO₄ > KNO₃ > (NH₄)H₂PO₄

<h3>Soution:</h3>

In (NH₄)₂HPO₄:

Mass of Nitrogen = N × 2 = 14 × 2 = 28 g.mol⁻¹

Molar Mass of (NH₄)₂HPO₄ = 132.06 g.mol⁻¹

Mass %age = Mass of N / M.Mass of (NH₄)₂HPO₄ × 100

Mass %age = 28 g.mol⁻¹ / 132.06 g.mol⁻¹ × 100

Mass %age = 21.20 %

In (NH₄)₂SO₄:

Mass of Nitrogen = N × 2 = 14 × 2 = 28 g.mol⁻¹

Molar Mass of (NH₄)₂SO₄ = 132.14 g.mol⁻¹

Mass %age = Mass of N / M.Mass of (NH₄)₂SO₄ × 100

Mass %age = 28 g.mol⁻¹ / 132.14 g.mol⁻¹ × 100

Mass %age = 21.18 %

In KNO₃:

Mass of Nitrogen = N × 1 = 14 × 1 = 14 g.mol⁻¹

Molar Mass of KNO₃ = 101.10 g.mol⁻¹

Mass %age = Mass of N / M.Mass of KNO₃ × 100

Mass %age = 14 g.mol⁻¹ / 101.10 g.mol⁻¹ × 100

Mass %age = 13.84 %

In (NH₄)H₂PO₄:

Mass of Nitrogen = N × 1 = 14 × 1 = 14 g.mol⁻¹

Molar Mass of (NH₄)H₂PO₄ = 115.03 g.mol⁻¹

Mass %age = Mass of N / M.Mass of (NH₄)H₂PO₄ × 100

Mass %age = 14 g.mol⁻¹ / 115.03 g.mol⁻¹ × 100

Mass %age = 12.17 %

In NH₃:

Mass of Nitrogen = N × 1 = 14 × 1 = 14 g.mol⁻¹

Molar Mass of NH₃ = 132.14 g.mol⁻¹

Mass %age = Mass of N / M.Mass of NH₃ × 100

Mass %age = 14 g.mol⁻¹ / 17.03 g.mol⁻¹ × 100

Mass %age = 82.20 %

In NH₄NO₃:

Mass of Nitrogen = N × 2 = 14 × 2 = 28 g.mol⁻¹

Molar Mass of NH₄NO₃ = 80.04 g.mol⁻¹

Mass %age = Mass of N / M.Mass of NH₄NO₃ × 100

Mass %age = 28 g.mol⁻¹ / 80.04 g.mol⁻¹ × 100

Mass %age = 34.98 %

5 0

3 years ago

Combustion of hydrocarbons such as dodecane (C12H26) produces carbon dioxide, a "greenhouse gas." Greenhouse gases in the Earth'

miss Akunina [59]

Answer:

A. 2C12H26(l) + 37O2(g) —> 24CO2(g) + 26H2O(g)

B. 761.42 L

Explanation:

A. Step 1:

The equation for the reaction.

C12H26(l) + O2(g) —> CO2(g) + H2O(g)

A. Step 2:

Balancing the equation.

The equation can be balance as follow:

C12H26(l) + O2(g) —> CO2(g) + H2O(g)

There are 12 atoms of C on the left side and 1 atom on the right side. It can be balance by putting 12 in front of CO2 as illustrated below:

C12H26(l) + O2(g) —> 12CO2(g) + H2O(g)

There are 26 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 13 in front of H2O as illustrated below:

C12H26(l) + O2(g) —> 12CO2(g) + 13H2O(g)

Now, there are a total of 37 atoms of O2 on the right side and 2 atoms on the left. It can be balance by putting 37/2 in front of O2 as illustrated below:

C12H26(l) + 37/2O2(g) —> 12CO2(g) + 13H2O(g)

Multiply through by 2 to clear the fraction from the equation.

2C12H26(l) + 37O2(g) —> 24CO2(g) + 26H2O(g)

Now the equation is balanced

B. Step 1:

We'll by obtaining the number of mole of C12H26 in 0.450 kg of C12H26. This is illustrated below:

Molar Mass of C12H26 = (12x12) + (26x1) = 144 + 26 = 170g/mol

Mass of C12H26 = 0.450 kg = 0.450x1000 = 450g

Number of mole of C12H26 =?

Number of mole = Mass/Molar Mass

Number of mole of C12H26 = 450/170

Number of mole of C12H26 = 2.65 moles

B. Step 2:

Determination of the number of mole of CO2 produced by the reaction. This is illustrated below:

2C12H26(l) + 37O2(g) —> 24CO2(g) + 26H2O(g)

From the balanced equation above,

2 moles of C12H26 produced 24 moles of CO2.

Therefore, 2.65 moles of C12H26 will produce = (2.65x24)/2 = 31.8 moles of CO2.

B. Step 3:

Determination of the volume of CO2 produced by the reaction.

Pressure (P) = 1 atm

Temperature (T) = 19°C = 19°C + 273 = 292K

Gas constant (R) = 0.082atm.L/Kmol

Number of mole (n) = 31.8 moles

Volume (V) =?

The volume of CO2 produced by the reaction can b obtained by applying the ideal gas equation as follow:

PV = nRT

1 x V = 31.8 x 0.082 x 292

V = 761.42 L

Therefore, the volume of CO2 produced is 761.42 L

5 0

3 years ago

Read 2 more answers

What are the rows of the periodic table called?

Sergio039 [100]

Answer:

"The elements are arranged in seven horizontal rows,called periods or series,and 18 vertical columns,called Groups."

Explanation:

Risk*

4 0

2 years ago

I need help with this please

jarptica [38.1K]

Answer: the place that i put the letters is how it should look also 75% of your peas are green

Explanation:

3 0

3 years ago

A serving of soup contains 5.0 g of fat, 20.0 g of carbohydrates, and 3.0 g of protein. Determine how many kilocalories (kcal) a

marta [7]

Answer: The amount of kilocalories contained in the given serving of soup is 0.137 kCal

Explanation:

As per the USDA:

Carbohydrates provide 4 calories per gram, protein provides 4 calories per gram, and fat provides 9 calories per gram.

We are given

Mass of fat in the soup serving = 5.0 g

Mass of carbohydrates in the soup serving = 20.0 g

Mass of protein in the soup serving = 3.0 g

Conversion factor used: 1 kCal = 1000 Cal

Applying unitary method:

For Fat:

1 gram of fat provides 9 calories

So, 5.0 gram of fat will provide = $\frac{9}{1}\times 5.0=45Cal=0.045kCal$

For Carbohydrates:

1 gram of carbohydrates provides 4 calories

So, 20.0 gram of carbohydrates will provide = $\frac{4}{1}\times 20.0=80Cal=0.080kCal$

For Proteins:

1 gram of proteins provides 4 calories

So, 3.0 gram of fat will provide = $\frac{4}{1}\times 3=12Cal=0.012kCal$

Total kilocalories per serving = [0.045 + 0.080 + 0.012] kCal = 0.137 kCal

Hence, the amount of kilocalories contained in the given serving of soup is 0.137 kCal

4 0

3 years ago