Answer:
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
[tex]252.3 \ g \ H_2S(\frac{1 \ mol \ H_2S}{34.09 \ g \ H_2S} )(\frac{6.022 \cdot 10^{23} \ molecules \ H_2S}{1 \ mol \ H_2S} )[/tex] = 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
Answer:
[tex]\boxed {\boxed {\sf 4.457*10^{24} \ molecules \ H_2S}}[/tex]
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.
[tex]252.3 / g * \frac{1 \ mol \ H_2S}{34.086 \ g }[/tex]
Multiply. The grams will cancel each other out.
[tex]\frac{252.3 / mol }{34.086 \ }=7.40186587 \ mol[/tex]
Finally, found the number of molecules using Avogadro's number (There are 6.022*10²³ molecules in 1 mole).
[tex]7.40186587 \ mol \ H_2S*\frac{6.022*10^{23} molecules \ H_2S}{1 \ mol \ H_2S}[/tex]
Multiply. The mole (mol) will cancel each other out.
[tex]7.40186587*{6.022*10^{23}\ molecules \ H_2S} = 4.45740363 *10^{24} \ molecules \ H_2S[/tex]
Round to the correct number of significant figures. The sample had 4 sig figs (2, 5, 2, 3), so round to 4 sig figs.
[tex]4.457*10^{24} \ molecules \ H_2S[/tex]
There are about 4.457 * 10²⁴ molecules of H₂S
