Explain the process that creates chemical elements lighter than iron, including evidence.

A 21.82 gram sample of an organic compound containing C, H and O is analyzed by combustion analysis and 21.33 grams of CO2 and 4

morpeh [17]

<u>Answer:</u> The molecular formula for the given organic compound is $C_2H_2O_4$

<u>Explanation:</u>

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=21.33g$

Mass of $H_2O=4.366g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 21.33 g of carbon dioxide, $\frac{12}{44}\times 21.33=5.82g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 4.366 g of water, $\frac{2}{18}\times 4.366=0.485g$ of hydrogen will be contained.

Mass of oxygen in the compound = (21.82) - (5.82 + 0.485) = 15.515 g

To formulate the empirical formula, we need to follow some steps:

<u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{5.82g}{12g/mole}=0.485moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.485g}{1g/mole}=0.485moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{15.515g}{16g/mole}=0.969moles$

<u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.485 moles.

For Carbon = $\frac{0.485}{0.485}=1$

For Hydrogen = $\frac{0.485}{0.485}=1$

For Oxygen = $\frac{0.969}{0.485}=1.99\approx 2$

<u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : H : O = 1 : 1 : 2

Hence, the empirical formula for the given compound is $C_1H_{1}O_2=CHO_2$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 90.04 g/mol

Mass of empirical formula = 45 g/mol

Putting values in above equation, we get:

$n=\frac{90.04g/mol}{45g/mol}=2$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 2)}H_{(1\times 2)}O_{(2\times 2)}=C_2H_2O_4$

Thus, the molecular formula for the given organic compound is $C_2H_2O_4$

4 0

4 years ago

A property is a characteristic of a substance that can be observed and does not change the identity of the substance. T/F

Murljashka [212]

The correct answer is false. The statement given does not describe a property in general. However, it speaks of a specific type of property which is the physical property. This property is the one that does not change the identity of a substance. A property can also be a chemical property where the identity of a substance is changed.

4 0

3 years ago

How many moles of O2- ions are there in 0.450 moles of aluminum oxide, Al2O3?

Mashutka [201]

Answer:

1.35 moles of O²⁻

21.6 grams of O²⁻

Explanation:

We know that the charge on Aluminium ion is +3 (i.e. Al³⁺) while, the charge on Oxide ion is -2 (i.e. O²⁻). Therefore, the overall neutral Al₂O₃ compound has 2 Al³⁺ ions and 3 O²⁻ ions. Since, we can say that,

1 mole of Al₂O3 contains = 3 moles of O²⁻ ions

So,

0.450 moles of Al₂O₃ will have = X g of O²⁻

Solving for X,

X = 0.450 mol × 3 mol ÷ 1 mol

X = 1.35 moles of O²⁻

As the mass of an atom is mainly due to the presence of protons and neutrons hence, the addition of two electrons (-ve 2 shows two gained electron) to Oxygen will make a negligible change to the atomic masss of Oxygen because electron is said to be almost 1800 times lighter than proton. Hence, the ionic mass of O²⁻ will be 16 g/mol and the mass of given moles is calculated as,

Mass = Moles × Ionic Mass

Mass = 1.35 mol × 16 g/mol

Mass = 21.6 g

5 0

3 years ago

The air pressure in a tire is 2.38 atm. What is the pressure in kilopascals.

Anna71 [15]

Answer:

The answer is

Explanation:

To find the pressure in kilopascals we must first find the pressure in Pascal

To find the pressure in Pascal we use the conversion

1 atm = 101 , 325 Pa

If 1 atm = 101325 Pa

then 2.38 atm = 2.38 × 101325

= 241153.5 Pa

Converting it into kPa we have the final answer as

Hope this helps you

8 0

3 years ago

Revise and repeat: Is more water always better? Create your own experiments to find the ideal amount of water for each kind of p

sergij07 [2.7K]

More water is not always better. For example; cacti only need water about every two weeks, the same with succulent plants. Not every plant needs to be watered every day, or the plant may be overwatered and die.

7 0

3 years ago