Chemistry

Chemistry

Problem

A sample contains 1.50×10241.50\times10^{24} molecules of carbon dioxide. What is the mass of the sample to the correct number of significant figures? a) 7.0×101 g7.0 \times 10^{1}\,\text{g} b) 1.8×101 g1.8 \times 10^{1}\,\text{g} c) 1.10×102 g1.10 \times 10^{2}\,\text{g} d) 3.0×101 g3.0 \times 10^{1}\,\text{g}
Intuitive explanation

The key is converting from individual molecules to moles using Avogadro's number, then from moles to grams using molar mass. Since you're given a count of particles, divide by 6.02×10236.02 \times 10^{23} molecules/mol to find how many moles you have, then multiply by CO₂'s molar mass (44.01 g/mol). Watch your significant figures throughout—your given number has three sig figs, so your answer should too.

Intuitive explanation

The key is converting from individual molecules to moles using Avogadro's number, then from moles to grams using molar mass. Since you're given a count of particles, divide by 6.02×10236.02 \times 10^{23} molecules/mol to find how many moles you have, then multiply by CO₂'s molar mass (44.01 g/mol). Watch your significant figures throughout—your given number has three sig figs, so your answer should too.

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