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3 years ago

Which of the following correctly identifies the number of each element involved in the chemical formulas

Chemistry

1 answer:

lakkis [162]3 years ago

8 0

D
If an element doesn’t have a number next to it that means there is only one. There a 4 hydrogens because the number is attached to the hydrogen atom. If there were 4 NH molecules the NH would be in parentheses and the 4 would be outside. Same goes for the oxygen atom and CO3 molecule.

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How many moles of pentane are in 1.48x1021

vodka [1.7K]

multiply the number of each atom with its molecular mass. (see the periodic table)

5*12 + 12*1 = 72 gram per mole.

Or more accurately: 5*12.01078 + 12*1.007947 = 72.149264 g/mole

7 0

3 years ago

Read 2 more answers

Calculate in witch material - sodium or zinc sulphide is the highest percentage by mass of sulfur

rjkz [21]

Answer:

sodium sulphide.

Explanation:

First, let us obtain the percentage of sulphur in both compounds. This is illustrated below:

For sodium sulphide(Na₂S):

Molar Mass of Na₂S = (23x2) + 32 = 46 + 32 = 78g/mol

Percentage of sulphur in Na₂S is given by:

32/78 x 100 = 41%

For zinc sulphide(ZnS):

Molar Mass of ZnS = 65.4 + 32 = 97.4g/mol

Percentage of sulphur in ZnS is given by:

32/97.4 x 100 = 33%

From the results obtained sulphur has the highest percentage by mass in sodium sulphide.

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3 years ago

A sample of xenon gas occupies a volume of 5.24 L at 411 K. If the pressure remains constant, at what temperature will this

stiks02 [169]

Answer:

161.57 K

Explanation:

V1/T1 = v2/T2

(5.24 L)/(411 K) = (2.06 L)/T2

T2 = 161.57 K

8 0

2 years ago

Why is photosynthesis important for ecosystems everywhere

Masja [62]

Photosynthesis is very important for our biosphere. Photosynthetic plants convert solar energy into the chemical energy and that stored chemical energy flows into herbivores, predators, parasites, decomposers, and all other forms of life . In the photosynthetic process, light energy is absorbed by the chlorophyll molecules of plants to convert carbon dioxide and water into carbohydrates and oxygen gas. Proteins, fats, nucleic acids, and other compounds also are synthesized during the process.And photosynthesis play important role for maintaining the atmospheric carbon dioxide and oxygen ratio.During the photosynthesis plants absorbs carbon dioxide and release oxygen to atmosphere.All living organisms need oxygen,They cant survive without oxygen.

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3 years ago

How many moles are contained 80.3 gram of sm(no3)3

swat32

<h3>Answer:</h3>

0.239 mol Sm(NO₃)₃

<h3>General Formulas and Concepts:</h3>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

Reading a Periodic Table
Moles

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 80.3 g Sm(NO₃)₃

[Solve] moles Sm(NO₃)₃

<u>Step 2: Identify Conversions</u>

[PT] Molar Mass of Sm - 150.36 g/mol

[PT] Molar Mass of N - 14.01 g/mol

[PT] Molar Mass of O - 16.00 g/mol

Molar Mass of Sm(NO₃)₃ - 150.36 + 3[14.01 + 3(16.00)] = 336.39 g/mol

<u>Step 3: Convert</u>

[DA] Set up: $\displaystyle 80.3 \ g \ Sm(NO_3)_3(\frac{1 \ mol \ Sm(NO_3)_3}{336.39 \ g \ Sm(NO_3)_3})$
[DA] Divide [Cancel out units]: $\displaystyle 0.238711 \ mol \ Sm(NO_3)_3$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 3 sig figs.</em>

0.238711 mol Sm(NO₃)₃ ≈ 0.239 mol Sm(NO₃)₃

3 0

2 years ago