We know that the water in humidification systems is not always pure, but we are targeting an absolute humity of 43.9 mg/L when the air hits the lungs. Assuming our unpure water is in an ideal solution with other material and we heat our humidification system to 50.0 celsius degree, what is the minimum mol fraction of water that can provide enough water vapour to the air to allow us to reach our target of 43.9 mg/L in the air phase? Assume atmospheric pressure is 101325 Pa. The molecular weight of water is 18.01528 g/mol.