Pure ethanol has a density of 0.78945 g/cm ³ at 20.0 °C and 0.80625 g/cm³ at 0.0° C. What will be the difference in mass that a 500.0mL flask will hold at 0.0°C from that at 20.0 °C? Assume the volume of the sample at 0.0 °C is exactly the same as the volume of the sample at 20.0°C.