To determine the number of chlorine molecules in a given volume of chlorine gas at standard temperature and pressure (STP), we can use the ideal gas law equation, which relates the number of molecules to the volume, pressure, and temperature of the gas.
STP conditions are defined as a temperature of 273.15 Kelvin (0 degrees Celsius) and a pressure of 1 atmosphere (101.325 kilopascals or 760 millimeters of mercury). The molar volume of an ideal gas at STP is approximately 22.4 liters (or 22,400 cubic centimeters) per mole.
To calculate the number of chlorine molecules in 30 cm³ of chlorine gas at STP, we need to convert the volume to liters and then use Avogadro's number, which states that there are 6.022 × 10^23 molecules per mole.
1 cm³ = 0.001 liters
Volume of chlorine gas = 30 cm³ × 0.001 liters/cm³ = 0.03 liters
Number of moles of chlorine gas = volume of chlorine gas / molar volume at STP = 0.03 liters / 22.4 liters/mol ≈ 0.00134 moles
Number of chlorine molecules = number of moles × Avogadro's number = 0.00134 moles × 6.022 × 10^23 molecules/mole ≈ 8.07 × 10^20 chlorine molecules
Therefore, there are approximately 8.07 × 10^20 chlorine molecules in 30 cm³ of chlorine gas at STP.