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jenyasd209 [6]
3 years ago
10

How many grams are in 6.78 x 10^24 atoms of He?

Chemistry
2 answers:
DiKsa [7]3 years ago
8 0

Answer:

45.05g

Explanation:

Based on the Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02x10^23 atoms.

From the above findings,

1 mole of He also contains 6.02x10^23 atoms.

1 mole of He = 4g

If 4g of He contains 6.02x10^23 atoms,

then Xg of He will contain 6.78x10^24 atoms i.e

Xg of He = (4x6.78x10^24)/6.02x10^23

Xg of He = 45.05g

Therefore, 45.05g of He contains 6.78x10^24 atoms

Gala2k [10]3 years ago
4 0

Answer:

45.05grams

Explanation:

Number of atoms present in a substance = number of moles of the substance × Avogadro's number

Given, number of atoms = 6.78×10^24

Number of moles = mass / molar mass

Molar mass of Helium = 4g/mol

Avogadro's number = 6.02×10^23

Therefore,

6.78×10^24=(m/4)×(6.02×10^23)

6.78×10^24=(6.02×10^23×m)/4

Cross multiply

6.02×10^23×m=4×6.78×10^24

Divide both sides by 6.02×10^23

m=(4×6.78×10^24)/6.02×10^23

m=(27.12×10^24)/6.02×10^23

m=45.05grams

Therefore, there are 45.05grams in 6.78×10^24 atoms of helium

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What is the correct balanced equation for the reaction that occurs when aqueous ammonium chloride reacts with aqueous barium nit
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Answer:

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Explanation:

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NH_{4}Cl + Ba(NO_{3} )_{2} ⇒  BaCl_{2} + NH_{4}NO_{3}

The equation above represents an unbalanced equation of the reaction of aqueous ammonium chloride  with aqueous barium nitrate .we can balance this equation by adding the right coefficients to reactants and product.

2NH_{4}Cl + Ba(NO_{3} )_{2} ⇒  BaCl_{2} + 2NH_{4}NO_{3}

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Complete the following single replacement reaction. If they don’t react, just write “NR”
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Here we have to complete the given single replacement reactions.

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4) Ni (s) + KBr (aq) → NiBr₂ (aq) + K (s)

5) Zn (s) + Ca(NO₃)₂ (aq) → Zn(NO₃)₂ (aq)  + Ca (s)

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The replacement reactions can be explained in light of the redox potential.

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We know the half cell reactions in which the standard reduction potentials are positive are allowed.

1) The reaction is possible as Cu²⁺/Cu and Fe/Fe²⁺ standard reduction potentials are positive.

2) The reaction is not possible as Cu/Cu²⁺ and Fe²⁺/Fe standard reduction potentials are negative.

3) The reaction is not possible as Ni²⁺/Ni standard reduction potential is negative.

4) The reaction is possible as Ni/Ni²⁺ standard reduction potential is positive.

5) The reaction is possible as Zn/Zn²⁺ standard reduction potential is positive.

6) The reaction is possible as Zn²⁺/Zn standard reduction potential is negative.

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