Which of the following samples contains approximately 2 moles of particles?

• A. 12 grams of carbon (C)
• B. 64 grams of oxygen gas (O_2)
• C. 23 grams of sodium (Na)
• D. 36 grams of water (H_2O)

Answer: (D)

Verified step by step guidance

1. Identify the molar mass of each substance given in the problem. The molar mass is the mass of one mole of particles (atoms or molecules) and can be found using the periodic table: for example, carbon (C) has a molar mass of approximately 12 g/mol, oxygen gas (O_2) about 32 g/mol, sodium (Na) about 23 g/mol, and water (H_2O) about 18 g/mol.
2. Calculate the number of moles in each sample by using the formula: \(\text{moles} = \frac{\text{mass of sample (g)}}{\text{molar mass (g/mol)}}\). This will give you the amount of substance in moles for each sample.
3. For carbon: \(\text{moles} = \frac{12\,g}{12\,g/mol}\). For oxygen gas: \(\text{moles} = \frac{64\,g}{32\,g/mol}\). For sodium: \(\text{moles} = \frac{23\,g}{23\,g/mol}\). For water: \(\text{moles} = \frac{36\,g}{18\,g/mol}\).
4. Compare the calculated moles for each sample to see which one is closest to 2 moles. This comparison will help you identify the sample that contains approximately 2 moles of particles.
5. Remember that the term 'particles' refers to atoms for elemental substances like carbon and sodium, and molecules for molecular substances like oxygen gas and water. This distinction is important when interpreting the results.