How do i read a solubility curve to answer a question like: at what temp will 50g of potassium nitrate complete saturate 100cm3 of water

You need a graph of saturation concentration (in units of g/100 cc) along the y axis vs temperature (plotted on the x axis). Look up the temperature on the curve that corresponds 50 g/100 cm^3. That will be the answer.

According to data in my Chem Physics handbook, the saturation concentration of KNO3 in H2O is 50 g/100 cm^3 at about 40 C. I only have data points at 0, 20 and 100 C, and so should plot a curve for a more accurate value.

To answer this question, you will need to understand how to read and interpret a solubility curve. Here's how you can do it step by step:

Step 1: Find the solubility curve for potassium nitrate (KNO3) in water. This can be found in a reference book, textbook, or online resource.

Step 2: Identify the temperature axis (x-axis) and the solubility axis (y-axis) on the graph. The temperature is typically measured in degrees Celsius (°C), and the solubility is usually expressed in grams of solute per 100 grams of solvent or 100cm3 of water.

Step 3: Locate the point on the graph where the line representing potassium nitrate intersects with the solubility value of 50g (the amount of potassium nitrate) and follows along the 100cm3 line (the volume of water).

Step 4: From the point where the line intersects, draw a straight line parallel to the temperature axis until it meets the axis. This line represents the temperature at which the solubility of the potassium nitrate is 50g in 100cm3 of water.

Step 5: Read the value on the temperature axis where the line intersects. This temperature value is the answer to the question – the temperature at which 50g of potassium nitrate completely saturates 100cm3 of water.

Keep in mind that the solubility curve provides information for a specific system, such as the solute and solvent combination. Different substances will have different solubility curves.