Question

How many molecules of H2 are present in 7.5 grams of H2? How many H atoms?

Answer 1

Answer:

The answer is 2.258 x 10^24 molecules are presented in 7.5 grams of H2.

Explanation:

I am going to use the chart that I attached to answer this question.

To convert grams to molecules we need to divide by the molar mass and multiply by 6.02 x 10^23, which is the value of a mole.

In this case the molar mass is 2 because the molar mass of H is 1 and we need to multiply by 2 to get the molar mass of 2 hydrogens.

Molar Mass = 1 x 2 = 2

Then, we need to divide the grams that we have by 2 to covert grams into moles. Finally, to convert moles into molecules we need to multiply the moles by 6.02 x 10^23.

7.5 grams / 2 = 3.75 moles

(3.75 moles)(6.02 x 10^23) = 2.258 x 10^24 molecules

Molecules are equal to atoms, so 2.258 x 10^24 molecules = 2.258 x 10^24 atoms

Answer 2

The number of molecules present in the hydrogen gas is 2.107 x 10²⁴ molecules.

The given parameters;

• mass of the hydrogen gas, = 7.5 grams

The molar mass of hydrogen gas is calculated as follows;

H₂ = 2 x 1 = 2

The number of moles is calculated as follows;

$moles = \frac{7.5}{2} = 3.5 \ moles$

The number of molecules present in the hydrogen gas is calculated as follows;

1 mole ------------ 6.02 x 10²³ molecules

3.5 moles ----------- ?

= 3.5 x 6.02 x 10²³

= 2.107 x 10²⁴ molecules.

Thus, the number of molecules present in the hydrogen gas is 2.107 x 10²⁴ molecules.

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