Student Objective Warm Up Identify the indicators that a chemical change/reaction has occurred. Warm Up WHAT DO YOU THINK???? How do you know if a chemical reaction has taken place??

Add to Physical vs Chemical Notes A PHYSICAL change affects only the _____________________ of the material, but does not make a _______ _________________. A CHEMICAL change forms _______ or more __________ substances.

Matter can undergo two kinds of changes… Matter can undergo two kinds of changes…. PHYSICAL changes and CHEMICAL changes.

Differences between chemical and physical changes… Add this to your worksheet & to your vocab. section!! Add 2 examples to 3rd box on vocab. paper from next two slides Chemical Change a change that forms one or more new substances. Physical Change a change that affects only the appearance of a material, but does not make a new substance.

Examples of Physical Changes….Why? tearing paper chopping wood molding clay melting ice

raw egg becomes cooked egg                                        raw egg becomes cooked egg                                                                      cake mix becomes cake                                                                                 paper becomes ash steel becomes rust EXAMPLES OF CHEMICAL CHANGES….Think about why each of these is a “chemical change”.

How do you know if a chemical reaction has taken place and a new substance is made? Use the following slides to find out as you complete your “Indicators of a Chemical Change or Reaction” worksheet

Indicators of a Chemical Reaction Occurring: Sometimes a gas is produced, which you might see as bubbles in a liquid.

Indicators of a Chemical Reaction Occurring: Other times, a solid may appear when two solutions are mixed. A solid that forms from mixing two solutions during a chemical reaction is called a precipitate.

Indicators of a Chemical Reaction Occurring: Still other times, a color change or a change in other properties may tell you that a new substance has formed.

Indicators of a Chemical Reaction Occurring: Sometimes heat and/or light are produced when a new substance is formed.

IMPORTANT All of these indicators are evidence of a chemical reaction. But they do not always mean that a chemical reaction has taken place. Sometimes, physical changes give similar results! Take for example boiling water. Don’t you observe bubbles indicating a gas has been made, but is it a new substance? In this case, the liquid water has turned into gas water……it’s still water! Just a change in state has occurred, not the creation of a new substance! The key characteristic of a chemical reaction is the production of new substances that are chemically different from the starting substances!

Touching Cactus Gives Little Pricklies. REVIEW: INDICATORS OF A CHEMICAL REACTION (List these at the bottom of your worksheet) Temperature change Color Change: Light produced Chemical Interactions Page 19 Gas Produced Precipitate Touching Cactus Gives Little Pricklies.

Virtual Lab: Reversible & Irreversible changes. Fill-in-the-Blanks *Reading Comprehension - Properties and Changes Virtual Lab: Reversible & Irreversible changes. http://www.bbc.co.uk/bitesize/ks2/science/materials/changes_materials/play/ Click yellow “Fullscreen” button Sound off, subtitles on When you have completed the mission click yellow “Close” button & then scroll down to find QUIZ. Website for Fill-in-the-blanks: http://education.jlab.org/reading/properties_and_changes.html Website for Virtual Lab: http://www.bbc.co.uk/schools/ks2bitesize/science/materials/reversible_irreversible_changes/play.shtml Website for Mission: http://www.bbc.co.uk/bitesize/ks2/science/materials/

Try these sites to see if you and your partner really know about physical and chemical changes. http://www.edinformatics.com/math_science/a_p_chem.htm http://www.quia.com/quiz/303980.html http://www.fordhamprep.com/gcurran/sho/sho/review/rev15b.htm

Where’s the Evidence of a Chemical Reaction? Conclusions: Where’s the Evidence of a Chemical Reaction? Look at the reactions on the next chart. Fill in the last two columns by putting your answers on your worksheet.

Where’s the Evidence? Activity Reaction Observations Before Reaction 1. Sodium carbonate (powder) + hydrochloric acid   2. sugar + heat 3. Copper sulfate + sodium carbonate solutions Was there a chemical reaction? Indicators? Observations After Reaction Describe the change that occurred

Where’s the Evidence? Activity Reaction Observations Before Reaction 1. Sodium carbonate (powder) + hydrochloric acid   2. sugar + heat 3. Copper sulfate + sodium carbonate solutions Was there a chemical reaction? Indicators? Observations After Reaction Describe the change that occurred YES color change gas produced turned white bubbles formed turned brown looks liquidy YES color change thick stuff formed in the clear liquid 2 clear liquids turned blue YES color change precipitate formed