How many molecules are in 252.3 g H2S?

4.457 × 10²⁴ molecules H₂S

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

252.3 g H₂S

Step 2: Identify Conversions

Avogadro's Number

Molar Mass of H - 1.01 g/mol

Molar Mass of S - 32.07 g/mol

Molar Mass of H₂S - 2(1.01) + 32.07 = 34.09 g/mol

Step 3: Convert

= 4.45688 × 10²⁴ molecules H₂S

Step 4: Check

We are given 4 sig figs. Follow sig fig rules and round.

4.45688 × 10²⁴ molecules H₂S ≈ 4.457 × 10²⁴ molecules H₂S

Explanation:

First, find the molar mass of H₂S

Use the Periodic Table to find the mass of hydrogen and sulfur.

To find the molar mass of H₂S, multiply the molar mass of the elements by the number of atoms of the element.

Add.

Next, find the number of moles in the sample (252.3 g)  Use the ratio of grams to moles.

Multiply. The grams will cancel each other out.

Finally, found the number of molecules using Avogadro's number (There are 6.022*10²³ molecules in 1 mole).

Multiply. The mole (mol) will cancel each other out.

Round to the correct number of significant figures. The sample had 4 sig figs (2, 5, 2, 3), so round to 4 sig figs.

There are about 4.457 * 10²⁴ molecules of H₂S

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