You light up my life
conductivity
Chem Catalyst
1) If you were to drop a spoonful of salt (NaCl) into a glass of water, what would the salt dissolve? Would a gold ring that is dropped into a glass of water Dissolve?
2) Why do these substance react so differently to water?
Unit 1 • Investigation V
The Big Question
– What patterns do we see in the properties of substances?
Unit 1 • Investigation V
You will be able to:
– Predict whether MgSO4(aq), epsom salts, will conduct electricity.
Build conductivity meters
• We use Christmas Tree lights with wires to form a conductivity meter
Unit 1 • Investigation V
(cont.)
(cont.)
Intro to electricity
• What is a circuit?• Open vs closed circuit• Short Circuit
Demonstration of dissolving and conductivity
Test to see if Kool-Aid will dissolve and/or conduct electricity
Both solid and solution (if applicable)
Revisit Mixtures and Substance change
Amount of SolubilityHomogeneous (H): Uniform Solution, can not determine
separate ingredientsHeterogeneous (He): Can determine ingredients, but
some mixing occursImmiscible (I): no mixing of ingredients at all
When water was added to create a solution:Was there a:Physical change (P) (no chemical reaction)Chemical change (C) (chemical reaction)
Unit 1 • Investigation V
Activity
• Purpose: This lesson allows you to collect evidence regarding some of the properties of substances, and look for patterns.
(cont.)
Lab set up
1. Form groups
2. Make sure each member has their own copy of all handouts
3. There are a number of stations around the room, groups will be rotating through them
4. Groups will take their conductivity test equipment with them as they move through the stations
Procedures to take at the stations1. Do not leave the conductivity meter connected in circuit
too long. These Christmas light burn out very fast
2. Do not connect wire to both ends of battery, creating a short (dangerous). This burns out the batteries extremely fast. Points will be deducted from group score for lab if this occurs
3. Once you test the materials at a station take paper clips off of beaker and dry them off. Separate all material
4. Do not place paper clips used to test one material or solution into a different one, (minimize Contamination)
Extra Lab Precautions
• Be aware about special conditions for the following materials:
• Ethanol (strong smelling)• Calcium Chloride Solution (can damage paper
clip, stain clothes)• Copper Sulfate solution (can damage paper
clip)
Before you perform experiments
• Make predictions as a group
The solvent will be water for each solution
When Done
• Answer questions based on lab with your partner(s)
• Make sure your have cleaned up after yourself
• Question and answer session will follow
Predict Test Results Test results Mixture type (H, He, I )
Change ? P, C, none
Solute Formula and Name
Conduct? Conduct Dissolve
Potassium sulfate (KCl)
Al(s)
C12H22O11(s) Sugar
NaCl(s) Salt
SiO2(s) Sand
C20H42(s)Parrafin wax
C2H6O(l) Ethanol
Cu(s)
CaCl2(s),
calcium chloride
CuSO4(s), copper sulfate
Tap Water (mixture)H2O(l) Distilled
Most objects can be sorted into one of 4 categories:
Whether it dissolves or notWhether it conducts or not
Unit 1 • Investigation V
NaCl – salt
CuCl2 – calcium chloride
CuSO4 – copper
sulfate
H2O – water
C12H22O11 – sugar
C2H6O – ethanol
Au – gold
Cu – copper
Al – aluminum
SiO2 – sand
C20H42 – paraffin
Dissolves
Yes No
Conducts
Yes Yes NoNo
Conducts
Notes
Conducts, dissolves Conducts, does not dissolve
Dissolves, does not conduct
Does not dissolve or conduct
Unit 1 • Investigation V
Wrap-Up
– Not all substances conduct electricity. – Substances that do conduct electricity
involve either solid metals, or metal-nonmetal compounds dissolved in water.
– Not all substances dissolve in water.