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3 years ago

Answer ASAP 30 points!! Why do elements and compounds qualify as pure substances?

Chemistry

2 answers:

AlladinOne [14]3 years ago

8 0

Answer:

Elements are made of only one kind of atom. ... The molecule is made up of two or more kinds of atoms. There is no physical change that can separate the compounds into more than one kind of substance. This makes a compound a pure substance.

Explanation:

MatroZZZ [7]3 years ago

3 0

Elements are made of only one kind of atom. The molecule is made up of two or more kinds of atoms. There is no physical change that can separate the compounds into more than one kind of substance. This makes a compound a pure substance.

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3.5g of a Certain compound X, known to be made of carbon, hydrogen, and perhaps oxygen, and to have a molecular molar mass of 15

shutvik [7]

Answer:

C₅H₁₀O₅

Explanation:

1. Calculate the mass of each element in 2.78 mg of X.

(a) Mass of C

$\text{Mass of C} = \text{5.13 g CO}_{2}\times \dfrac{\text{12.01 g C}}{\text{44.01 g }\text{CO}_{2}}= \text{1.400 g C}$

(b) Mass of H

$\text{Mass of H} = \text{2.10 g H$_{2}$O}\times \dfrac{\text{2.016 g H}}{\text{18.02 g H$_{2}$O}} = \text{0.2349 g H}$

(c) Mass of O

Mass of O = 3.5 - 1.400 - 0.2349 = 1.87 g

2. Calculate the moles of each element

$\text{Moles of C = 1400 mg C}\times\dfrac{\text{1 mmol C}}{\text{12.01 mg C }} = \text{116.6 mmol C}\\\\\text{Moles of H = 234.9 mg H} \times \dfrac{\text{1 mmol H}}{\text{1.008 mg H}} = \text{233.1 mmol H}\\\\\text{Moles of O = 1870 mg O} \times \dfrac{\text{1 mmol O}}{\text{16.00 mg O}} = \text{116 mmol O}$

3. Calculate the molar ratios

Divide all moles by the smallest number of moles.

$\text{C: } \dfrac{116.6}{116.6}= 1\\\\\text{H: } \dfrac{233.1}{116.6} = 1.999\\\\\text{O: } \dfrac{116}{116.6} = 1.00$

4. Round the ratios to the nearest integer

C:H:O = 1:2:1

5. Write the empirical formula

The empirical formula is CH₂O.

6. Calculate the molecular formula.

EF Mass = (12.01 + 2.016 + 16.00) u = 30.03 u

The molecular formula is an integral multiple of the empirical formula.

MF = (EF)ₙ

$n = \dfrac{\text{MF Mass}}{\text{EF Mass }} = \dfrac{\text{150 u}}{\text{30.03 u}} = 5.00 \approx 5$

MF = (CH₂O)₅ = C₅H₁₀O₅

The molecular formula of X is C₅H₁₀O₅.

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4 years ago

Five gases combined in a gas cylinder have the following partial pressures: 3.00 atm (N2), 1.80 atm (O2), 0.29 atm (Ar), 0.18 at

lisov135 [29]

This can be solved using Dalton's Law of Partial pressures. This law states that the total pressure exerted by a gas mixture is equal to the sum of the partial pressure of each gas in the mixture as if it exist alone in a container. In order to solve, we need the partial pressures of the gases given. Calculations are as follows:

P = 3.00 atm + 1.80 atm + 0.29 atm + 0.18 atm + 0.10 atm

P = 5.37 atm

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3 years ago

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What happens to the temperature and density of the material between points B and C?

makvit [3.9K]

Answer:

Temperature decreases and density increases

Explanation:

Let us remember that density of a material increases as the temperature of the material decreases. So the cooler a material becomes, the denser it becomes also.

Between points B and C, the material rapidly cools down and the temperature decreases accordingly. This ultimately results in an increase in density since cooler materials are denser than hot materials.

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3 years ago

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erica [24]

A. is balanced

B. is not balanced

C. is not balanced

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3 years ago

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sweet [91]

Answer:commutator then current are the answers. I just took the question.

Explanation:

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3 years ago

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