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AleksandrR [38]
2 years ago
5

Which sample of matter is classified as a substance

Chemistry
1 answer:
rosijanka [135]2 years ago
3 0

Answer:

Elements and Compounds. Any sample of matter that has the same physical and chemical properties throughout the sample is called a substanceAny sample of matter that has the same physical and chemical properties throughout the sample.

Explanation:

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Hello there
melamori03 [73]

if density = m(mass) / v(volume) then the answer would be 3

6 0
3 years ago
How many atoms are in 25.00 g of B.
iren2701 [21]

Answer:

\boxed {\boxed {\sf 1.393 *10^{24} \ atoms \ B}}

Explanation:

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

Use the molar mass (found on the Periodic Table) to convert from grams to moles.

  • Boron (B): 10.81 g/mol

Use this value as a ratio.

\frac {10.81 \ g \ B }{1 \ mol \ B}

Multiply by the given number of grams.

25.00 \ g \ B *\frac {10.81 \ g \ B }{1 \ mol \ B}

Flip the ratio so the grams of boron cancel out.

25.00 \ g \ B *\frac {1  \ mol \ B }{10.81 \ g \ B}

25.00 *\frac {1  \ mol \ B }{10.81 }

\frac {25.00 \ mol \ B }{10.81 }=2.312673451 \ mol \ B

<u>2. Convert Moles to Atoms</u>

We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.

\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}

Multiply by the number of moles we calculated.

2.312673451 \ mol \ B *\frac {6.02*10^{23} \ atoms \ B} {1 \ mol \ B}

The moles of boron cancel.

2.312673451  *\frac {6.02*10^{23} \ atoms \ B} {1 }

2.312673451  *6.02*10^{23} \ atoms \ B} =1.39269195*10^{24} \ atoms \ B

The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.

1.392\underline69195*10^{24} \ atoms \ B

The 6 tells us to round the 2 to a 3.

1.393 *10^{24} \ atoms \ B

25.00 grams of boron is equal to 1.393*10²⁴ atoms.

6 0
3 years ago
An example of a scientific law is the law of conservation of mass, which states that matter is neither created nor destroyed in
Amanda [17]

Answer:A) It was developed from past observations- true

It is subject to experimentation and revision.- false

It explains why mass is conserved- false

It predicts future observations-true

Explanation:

Before a hypothesis is proclaimed to be a law in science, numerous observation must have confirmed its validity and rigorous experimentation under carefully controlled conditions usually precedes the acceptance of a hypothesis as a law. The law of conservation of mass was developed from numerous past observation that proved its validity.

4 0
3 years ago
The shape of the BF3 molecule is best described as
Mars2501 [29]

Answer:

The shape of the BF3 molecule is best described as trigonal planar.

Explanation:

The Lewis Structure for BF3 is like this:

 _            _

| F |        | F |

   \          /

        B

         |

      | F |

       ---

It forms three angles of 120° each. The bonds are in the same planar that's why it is trigonal planar and they are exactly the same.

Boron and Fluorine have 3 covalent bonds, produced by electronic promotion that enables the 2py and 2pz orbitals, leaving an electron to pair in the 2px. So boron will have 3 possible electrons to pair in 2s1, 2px and 2py, remember that electronic configuration for B is 1s2, 2s2, 2p1

By hybridization between the orbitals 2s2 and 2p1, the electrons of F, can joined to make the covalent bond. The new B configuration is 1s2, 2s1, 2px1, 2py1 (these last three, hybrid orbitals)

       

5 0
3 years ago
What is the formula of iron(iii) oxide?
SCORPION-xisa [38]

Answer:

Fe2O3

Explanation:

8 0
2 years ago
Read 2 more answers
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