Middle School Physical Science › Determine whether a chemical reaction has occurred
Which of these is NOT an example of a chemical reaction?
Heating Zinc Chloride to its melting point of 290 °C and watching it turn to a liquid is an example of:
Cooking uses heat to cause chemical changes in food. For example, when you hard boil an egg, the hydrogen sulfide produced by heating the egg white can react with iron from the egg yolk to form a green ring around the yolk. How do you know a chemical reaction has occurred during this process?
A block of ice melting into a puddle of water is an example of:
The following equation represents what happens when you combine Hydrogen Chloride and Potassium Hydroxide: HCl + KOH → KCl + H2O. This is an example of:
You are doing a science experiment in your classroom. Your teacher gives you these instructions and tells you a chemical reaction will take place.
Materials: ammonium nitrate (NH4NO3), tap water(H2O), Ziploc bags, a graduated cylinder and a balance.
Procedure:
1. Measure out 5 grams of ammonium nitrate and place it directly into a Ziploc plastic bag.
2. Using a graduated cylinder, measure exactly 10 mL of water .
3. Quickly, pour the water into the bag of ammonium nitrate, remove excess air and seal the bag.
4. Gently squeeze the bag to mix the solid and water. Observe while holding the bag.
After doing the experiment you recorded the following observations:
Which of these is a sign that a chemical reaction took place when you mix the ammonium nitrate and the water?
Which of these is NOT a sign of a chemical reaction?
The difference between a chemical change and a physical change is:
An "indicator" is a substance that changes color to tell us whether another chemical is present in our solution. An example of an indicator is the substance called "methyl yellow" which makes a yellow color in the presence of an alkaline. Indicators changing color are a sign that what has occurred?
Hydrochloric acid breaking down food during digestion is an example of: