Before you read this, I suggest that you read posts 16.34, 16.35 and 18.29. In post 16.34, we noted that heat flows spontaneously from a hot object to a cold object. This process is shown in the picture above, where the temperature T1 is greater than the temperature T2, and the arrow shows the direction… Continue reading 18.30 Heat pumps

Before you read this, I suggest you read post 18.27. The picture above is almost the same as the second picture in post 18.27; a membrane (green) separates water molecules (blue) from a solution of big molecules (red) in water. The big molecules are too big to pass through the pores of the membrane. The… Continue reading 18.29 Reverse osmosis