Final answer:
To find the number of moles of SiO2 in a 43.0 g quartz crystal, divide the mass by the molar mass of SiO2 (60.08 g/mol), resulting in approximately 0.716 moles of SiO2.
Step-by-step explanation:
To calculate the number of moles of SiO2 in a quartz crystal with a mass of 43.0 g, we need to use the molar mass of SiO2. The molar mass of silicon dioxide (SiO2) is approximately 60.08 g/mol, which is the sum of the atomic mass of silicon (28.085 g/mol) plus twice the atomic mass of oxygen (2 x 15.999 g/mol).
Using this information, we can calculate the number of moles of SiO2 as follows:
Number of moles = Mass of substance (g) / Molar mass (g/mol) = 43.0 g / 60.08 g/mol ≈ 0.716 moles of SiO2
Therefore, a quartz crystal with a mass of 43.0 g contains approximately 0.716 moles of SiO2.