Base your answer to the following question on the information below and on your knowledge of chemistry.
In a laboratory activity, each of four different masses of KNO3(s) is placed in a separate test tube that contains 10.0 grams of H2O at 25°C.
When each sample is first placed in the water, the temperature of the mixture decreases. The mixture in each test tube is then stirred while it is heated in a hot water bath until all of the KNO3(s) is dissolved. The contents of each test tube are then cooled to the temperature at which KNO3 crystals first reappear. The procedure is repeated until the recrystallization temperatures for each mixture are consistent, as shown in the table below.
Data Table for the Laboratory Activity
Mixture | Mass of KNO3 (g) | Mass of H2O (g) | Temperature of Recrystallization (°C)
1 | 4.0 | 10.0 | 24
2 | 5.0 | 10.0 | 32
3 | 7.5 | 10.0 | 45
4 | 10.0 | 10.0 | 58
Determine the percent by mass concentration of KNO3 in mixture 2 after heating.