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.