Data in tables can be extremely useful and informative. Sometimes, though, making a graph of data makes relationships between variables much more clear than a table can. In this activity you will graph four sets of data on the same sheet of graph paper. These data describe the maximum solubility of four different substances in water as a function of temperature. Two of the substances are gases and two of the substances are solids.
Maximum solubility is also known as saturation. When a solution is saturated it means that the solvent has dissolved as much of the solute as it can and no more solute will dissolve. If more solute is added to a saturated solution it will not dissolve. If the solute is a solid it will remain visible in the solid phase. On the level of ordinary observation nothing appears to be happening. On the molecular level, particles of solid are constantly dissolving and exiting the solution to become solid again.
Here are the data you will graph:
|Temperature (°C)||Mass NaCl (g)
|Mass O2 (g)
|Mass NH3 (g)
|Mass C12H22O11 (g)
Table Sugar (sucrose)
The table shows the number of grams of solute that will combine with 100 g of water to make a saturated solution of that solute. For example, 34.5 g of NaCl plus 100.0 g of water make up 134.5 g of solution and this would be the maximum amount that would dissolve at 0°C.
The numbers in the table can be manipulated to find out how much solute you would add to any amount of water to make a saturated solution. Volumes of water in mL can stand for mass of water since for low temperatures because the density of water is 1 g/mL at 4°C. Think of it as a simple fraction. In the data given it states that 34.5 g of salt mixed with 100 g of water at 0°C make a saturated solution. That means that 134.5 g of solution contain 100 g water and 34.5 g salt. To turn this into a percentage by mass just divide and multiply by 100%:
34.5 g salt ------------------ x 100% = 26.14% 134.5 g solutionSay you want to make a saturated solution with 100 g of water:
26.14% salt means: (0.2614 g salt)/(1 g solution) Set up a proportion like this: 0.2614 g salt x g salt -------------- = ------------------------- 1 g solution (100 g water + x g salt)
this simplifies to: x 2614 0.2614 = --------- so x = ------------- = 35.39 g (100 + x) (1 - 0.2614) which is what we started with.
So, to prepare the solution described you would mix 35.39 g of salt with 100.0 g of water. The total mass of the solution you make would be 135.4 g. The table relates how much of each solute will dissolve in 100 g water at each temperature. For other amounts of water you must find the percentage and solve the equation given above to find the amount of solute to dissolve.
To make your graph:
Answer these questions on a separate sheet of paper using complete sentences. Show work for all mathematical questions.
For this assignment you must turn in the answers to these questions and your sheet of graph paper showing all four plots. This will count toward your lab grade.