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3 years ago

A solid substance turns directly into a gas. Which term describes this change?

Chemistry

2 answers:

igomit [66]3 years ago

8 0

Sublimation.

Since evaporation is liquid into gas, melting is solid into liquid and deposition is the geological process where sediments are added to land forms.

romanna [79]3 years ago

6 0

Answer:

sublimation

Explanation:

i just did on edgen :)

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Which condition applies when water boils at 100oC

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An ambient pressure of 1 atm

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3 years ago

rank the four gases (air, exhaled air, gas produced from the decomposition of H2O2, gas from decomposition of NaHCO3, in order o

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Answer: H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)

Initial important note:

Although NaHCO₃ contents oxygen atoms, and you can calculate its compositoin, the resulting gas does not containg pure oxygen gas (O₂). For the comparisson it is not useful to calculate the content of oxygent atoms, but the concentration of O₂ gas. As such, the gas from NaHCO₃ contains 0% of pure O₂, that is why it is ranked last.

1) Air:

Source: internet

Approximate 23%. It is variable, because air is not a pure substance but a mixture of gases, whose compositon is not unique.

2) Exhaled air:

Source: internet.

Approximate 13%. The compositon of the air changes in our lungs, due to the respiration process: we inhale fresh air with around 23% of oxygen, part of this oxygen pass to the cells (lungs - blood - heart - cells) and then it is exhaled with a lower content of air and a greater content of CO₂

3) Air from the decomposition of H₂O₂.

In this case we can do a chemical calculation, since we can state the chemical equation of the reaction:

i) Chemical Equation:

H₂O₂ (g) → H₂ (g) + O₂ (g)

ii) mole ratio of the products 1 mol H₂ : 1 mol O₂

iii) convert moles into mass (grams)

1 mol H₂ × 2 × 1.008 g/mol = 2.016 g

1 mol O₂ × 2 × 15.999 g/mol = 31.998 g

Composition, % = [31.998 g / (2.016 g + 31.998 g) ] × 100 ≈ 94%

4) Air from the decomposition of NaHCO₃:

i) chemical equation:

2 NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g)

ii) mole ratio: take into account only the gases in the products:

1 mol CO₂ (g) : 1 mol H₂O

iii) mass in grams

CO₂: molar mass ia approximately 44.01 g/mol

H₂O: molar mass is approximately 18.02 g/mol

iii) Those gases although have oxygen atoms, do not hae free oxygen gas, which is what we are compariing. That means, that from the decomposition of NaHCO₃ you get 0% oxygen gas.

5) The result is:

H₂O₂ (94%) > Air (23%) > Exhaled air (13%) > NaHCO₃ (0%)

7 0

3 years ago

Read 2 more answers

What mass of H2 is needed to react with 8.75 g of O2 according to the following equation: O2(g) + H2(g) → H2O(g)?

alina1380 [7]

Mass of H₂ needed to react with O₂ : 1.092 g

<h3>Further explanation</h3>

The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.

Reaction

O₂(g) + 2H₂(g) → 2H₂O(g)

mass of O₂ : 8.75 g

mol O₂(MW=32 g/mol) :

$\tt \dfrac{8.75}{32}=0.273$