Pre-Lab 19A: Solubility Curve of KNO3

Purpose

Solubility refers to the amount of solute that can be dissolved in a certain volume of solvent under certain conditions.

In this experiment, you will be examining the relationship between temperature and the solubility of potassium nitrate (KNO3).

The solvent will be water.

Using class data, you will construct a solubility curve for KNO3.

Key Question

• What is a solubility curve?

Background

• Define:

solution

solute

precipitate

Drawing

• Download or make a drawing of rock candy on a string

Section 2You will be dissolving potassium nitrate into warm waterEach lab station will have a different mass of KNO3:

NOTE: change from book: each lab station increases solute by1.00 grams (accuracy to the 100th place: two decimals):lab 1 = 1.00 glab 2 = 2.00 glab 3 = 3.00 getal……

Be certain you tare the mass panLiquid volume must be exact and to an accuracy 0.1 mlYou will heat, then cool the solution to form a precipitateThis is a critical step: record the temperature (accuracy

of 0.1 degrees C) at which you first see crystals gather at the bottom of the test tube

Clean up:

Pour the solution into the trash

Use a test tube brush and warm water to COMPLETELY clean the test tube

Also,

do not lick your fingers, why?

KNO3 is a laxative!!!!

Section 3:

SHOW YOUR WORK

for part A you will be calculating water’s mass NOT MEASURING!! (density of water = ? )

Part B: use part A ratio = unknown ratio

Record your solubility/temperature values on the data chart:

NOTE: data chart must have 7 data columns

Critical step: Your data MUST then be recorded on the chart on the white board

Thus, the board’s data is the data you will use for making your solubility graph

Section 4:

Make a solubility graph from the classes’ data

Use graphing rules

Add/change this to your lab:

d. Explain why

e. Show your work

Post Lab: