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3 years ago

In which atmosphere layer do humans live most of their life

Chemistry

1 answer:

marysya [2.9K]3 years ago

3 0

Troposphere, this is the layer of the atmosphere closest to the earths crust.

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How many chromium (II) ions would bond with 2 phosphate ions?

zvonat [6]

Answer:

ummmm I don't know of sorry

3 0

2 years ago

Cyclohexane, a commonly used organic solvent, is 85.6% c and 14.4% h by mass with a molar mass of 84.2 g/mol. what is its molecu

puteri [66]

The molecular formula of organic solvent is <em>C6H12</em>

<h2>calculation</h2><h3>find the empirical formula first as in step 1 and 2</h3>

Step 1: f<em>ind the moles of C and H</em>

moles = % composition/molar mass

from periodic table molar mass of C= 12 g/mol while that of H= 1 g/mol
moles is C is therefore = 85.6/12= 7. 13 moles
moles of H= 14.4/1 - 14.4 moles

Step 2: <em>calculate the mole fraction by dividing each mole by smallest number of mole(7.13)</em>

that is C= 7.13/7.13 = 1

H= 14.4/7.13 =2

the empirical formula is therefore = CH2

<h2>Then calculate the molecular formula from empirical formula</h2>

step 3: divide the grams molar mass by empirical formula mass

empirical formula mass = 12+(1 x2) = 14 g/mol

= 84.2/ 14 = 6

step 4: multiply each of the subscript within the empirical formula with the value gotten in step 3

that is [CH2]6 = C6H12 therefore the molecular formula = <u>C6H12</u>

8 0

3 years ago

A 0.271g sample of an unknown vapor occupies 294ml at 140C and 874mmHg. The emperical formula of the compound is CH2. How many m

Phoenix [80]

Using PV = nRT, we can calculate the moles of the sample.
874 mmHg = 116,524 Pa
n = PV/RT
n = 116,524 x 294 x 10⁻⁶ / 8.314 x (140 + 273)
n = 9.98 x 10⁻³ mol

moles = mass / Mr
Mr = 0.271/9.98 x 10⁻³
Mr = 27.2
Mass of empirical formula = 14
Repeat units = 27.2 / 14 ≈ 2

Formula of substance:
C₂H₄

Combustion equation:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

1 mole produces 2 moles of CO₂, so 3 moles will produce 6 moles CO₂

7 0

3 years ago

Which statement correctly describes an atom of the element helium? A. An atom of helium has a full outer energy level and is the

Citrus2011 [14]

The correct description for an atom of helium would be option C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.

4 0

3 years ago

How many grams of copper (II) hydroxide can be prepared from 2.4 grams of copper (II) nitrate (Cu(NO3)2 ) and excess sodium hydr

andreyandreev [35.5K]

Answer:

percentage yield = 67%

Explanation:

Mass of Cu(NO₃)₂ = 15.25 g

Mass of NaOH = 12.75 g

Percentage yield = ?

Solution:

Cu(NO₃)₂ + 2NaOH → Cu(OH)₂ + 2NaNO₃

Moles of Cu(NO₃)₂:

Number of moles = mass/ molar mass

Number of moles = 15.25 g /187.56 g/mol

Number of moles = 0.08 mol

Moles of NaOH :

Number of moles = mass/ molar mass

Number of moles = 12.75 g / 40 g/mol

Number of moles = 0.32 mol

Now we will compare the moles of Cu(OH)₂ with NaOH and Cu(NO₃)₂. NaOH : Cu(OH)₂

2 : 1

0.32 : 1/2×0.32 = 0.16 mol

Cu(NO₃)₂ : Cu(OH)₂

1 : 1

0.08 : 0.08

The number of moles produced by Cu(NO₃)₂ are less so it will limiting reactant.

Mass of Cu(OH)₂:

Mass = number of moles × molar mass

Mass = 0.08 mol × 97.6 g/mol

Mass = 7.808 g

Theoretical yield = 7.808 g

Percent yield:

percentage yield = Actual yield/ theoretical yield × 100

percentage yield = 5.23 g/ 7.808 g × 100

percentage yield = 0.67 × 100

percentage yield = 67%

5 0

2 years ago