Final answer:
To find the number of C atoms in 42.0 mL of ethanol, we need to calculate the mass of ethanol in grams and then use the concept of moles to find the number of C atoms. The number of C atoms in 33.138 g of ethanol is 1.440 x 10^23 C atoms.
Step-by-step explanation:
The density of ethanol (C2H5OH) is given as 0.789 g/mL. To find the number of C atoms in 42.0 mL of ethanol, we need to first calculate the mass of ethanol in grams using its density:
Mass of ethanol = Density x Volume = 0.789 g/mL x 42.0 mL = 33.138 g
The molar mass of ethanol (C2H5OH) is 46 g/mol, which means that 1 mole of ethanol contains 6.022 x 10^23 molecules (Avogadro's number). To find the number of C atoms in 33.138 g of ethanol, we can use the concept of moles:
Number of moles of ethanol = Mass of ethanol / Molar mass = 33.138 g / 46 g/mol = 0.720 moles
Since 1 mole of ethanol contains 2 C atoms, the number of C atoms in 33.138 g of ethanol will be:
Number of C atoms = Number of moles of ethanol x (2 C atoms / 1 mole) = 0.720 moles x 2 = 1.440 x 10^23 C atoms