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4 years ago

What is an astronomical unit? Why is this unit used to measure distances in the solar system?

2 answers:

7 0

An astronomical unit is a unit of measurement equal to 149.6 kilometers, the mean distance from the center of the earth to the center of the sun.

1 astronomical unit = 92955807.3 miles

VashaNatasha [74]4 years ago

3 0

A astronomical unit is to measure light years.

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In the Ohm's law formula, the letter E stands for

likoan [24]

<span>In the Ohm's law formula, the letter E stands for B. voltage.</span>

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3 years ago

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How many molecules are in 3.6 grams of NaCl? Question options:

Levart [38]

Answer:

$\boxed {\boxed {\sf 3.7 * 10^{22} \ molecules \ NaCl}}$

Explanation:

We are asked to find how many molecules are in 3.6 grams of sodium chloride.

<h3>1. Convert Grams to Moles </h3>

First, we convert grams to moles using the molar mass. These values are equivalent to atomic masses on the Periodic Table, but the units are grams per moles instead of atomic mass units. Look up the molar masses of the individual elements: sodium and chlorine.

Na: 22.9897693 g/mol
Cl: 35.45 g/mol

There are no subscripts in the chemical formula (NaCl), so we simply add the 2 molar masses.

NaCl: 22.9897693 + 35.45 = 58.4397693 g/mol

Now we will convert using dimensional analysis. First, set up a ratio using the molar mass.

$\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}$

We are converting 3.6 grams to moles, so we must multiply the ratio by this value.

$3.6 \ g \ NaCl *\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}$

Flip the ratio so the units of grams of sodium chloride cancel.

$3.6 \ g \ NaCl *\frac { 1 \ mol \ NaCl}{58.4397693 \ g \ NaCl}$

$3.6 *\frac { 1 \ mol \ NaCl}{58.4397693}$

$\frac { 3.6}{58.4397693} \ mol \ NaCl$

$0.06160188589 \ mol \ NaCl$

<h3>2. Convert Moles to Molecules </h3>

Next, we convert moles to molecules using Avogadro's Number. This is 6.022 × 10²³ and it tells us the number of particles (atoms, molecules, formula units, etc). In this case, the particles are molecules of sodium chloride. Let's set up another ratio.

$\frac {6.022 \times 10^{23} \ molecules \ NaCl}{ 1 \ mol \ NaCl}$

Multiply by the number of moles we calculated.

$0.06160188589 \ mol \ NaCl * \frac{6.022 \times 10^{23} \ molecules \ NaCl}{1 \ mol \ NaCl}$

The units of moles of sodium chloride cancel.

$0.06160188589 * \frac{6.022 \times 10^{23} \ molecules \ NaCl}{1 }$

$3.70966557*10^{22} \ molecules \ NaCl$

<h3>3. Round </h3>

The original measurement of grams (3.6) has 2 significant figures, so our answer must have the same. For the number we found, that is the tenths place. The 0 in the hundredth place tells us to leave the 7 in the tenth place.

$3.7 * 10^{22} \ molecules \ NaCl$

There are $3.7 * 10^{22} \ molecules \ NaCl$ in 3.6 grams and the correct answer is choice D.

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3 years ago

Cortisol (m = 362.47 g/mol) is a steroid hormone involved in protein synthesis. Medically, it has a major use in reducing inflam

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C21H30O5 is its molecular formula

The hydroxyl groups at positions 17 and 21 and the oxo groups at positions 3, 11, and 20 are substituted in the C21 steroid cortisone. Both a mouse and a human metabolite, it serves a purpose.

<h3>Molecular formula: What is it?</h3>

A chemical formula is a way to communicate information in chemistry about the proportions of atoms that make up a specific chemical compound or molecule. Chemical element symbols, numbers, and occasionally other symbols like parentheses, dashes, brackets, commas, and plus and minus signs are used to represent the chemical elements.

A molecule's molecular formula reveals which atoms and how many of each kind are included within it. No subscript is used if there is just one atom of a certain kind. A subscript is added to the symbol for an atom if it contains two or more of a certain type of atom.

To learn more about molecular formula visit:

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2 years ago

What layer in the atmosphere contains the ozone layer

Ksju [112]

The <u>Stratosphere</u> contains the Ozone layer in Earth's atmosphere.