4.3

Comparing the Concentrations of Saturated Solutions

Notes

-mass of solid=(dish+dry solution)-dish empty

-mass of water=(dish+saturated solution)-(dish+dry solution)

-mass of water=volume of water

-density of water=1 g/cm^3

-solubility: the concentration of saturated solution

Experimental Errors

1. Not shaking long enough

2. Not warming test tube

3. Not evaporated to constant mass

4. Splattering out of dish

5. Dish is not clean/dry



Gray-Box Questions

8. A student poured 60 g of sodium nitrate into 100 cm^3 of water and observed that all the solid dissolved. Which of the following can she conclude about the solubility of sodium nitrate in water?

IT CAN BE 60g/100cm^3, BUT ITS MOST LIKELY GREATER THAN 60g/100cm^3

9. A solid is placed in a container with water and stirred thoroughly. Some solid dissolves and some remains at the bottom of the container.

a- Will adding more water and stirring cause more of the solid to dissolve?

YES, BECAUSE IT'S A SATURATED SOLUTION SO MORE WATER AND MORE SOLID WILL BALANCE OUT.

b- Does adding more water increase the solubility of the solid?

NO, THE SOLUBILITY IS A CHARACTERISTIC PROPERTY OF THE SOLID.

10. (graph)

11. (graph)

12. Suppose that 200 cm^3 of a saturated solution of potassium nitrate were left standing in an open beaker on you lab desk for three weeks. During this time most of the water evaporated.

a- Would the mass of potassium nitrate dissolved in the solution change?

YES, THE AMOUNT OF MASS OF DISSOLVED SOLID DECREASES BECAUSE THERE IS LESS WATER TO DISSOLVE SOLID.

b- Would the concentration of the potassium nitrate solution change during the three weeks?

NO, BECAUSE IT'S A SATURATED SOLUTION.