# 4.3

## 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.