In this lab you will be dealing several chemicals that can irritate your skin. Take all precautions to prevent contact with these chemicals.
Use goggles to protect your eyes and an apron to protect your clothes.
A chemical change always results in the formation of a new substance. A chemical reaction is a process in which a chemical change occurs. However, it may not always be obvious when a chemical reaction has occurred.
In this activity, you will investigate several supposed reactions and determine whether a chemical change has taken place.
What are some signs that a chemical reaction has taken place?
Materials and Equipment
4 small plastic cups
two plastic spoons
10 ml graduated cyclinder
10cm square sheet of aluminum foil
dilute hydrochloric acid (HCl) in a dropper bottle
sodium carbonate powder
copper sulfate solution
sodium carbonate solution
A "dry lab" activity includes collected data and/or a video solution for your convenience. You can simply watch the following video and use the provided data, or if you wish to perform this lab for yourself, follow the procedure steps 1 through 16 described in the video. The same steps are included in written form in the documents available for download on the bottom of this page.
Analyzing and Interpreting
What do your observations tell you about the supposed chemical reactions? Did a chemical reaction occur in each case? Explain your answers.
A student performing the procedure steps 1 through 16 recorded the following observations and results. What do these results indicate about the three supposed chemical reactions - did a chemical change occur in each case? Explain your answers.
Observations and Results
Sodium carbonate powder + HCl
Fizzed during reaction, produced bubbles of gas
Sugar slowly melts, then turned into a dark black substance, gas given off, reaction produced a sweet smell.
Copper sulfate + sodium carbonate solution
Produced a greenish solid precipitate
When sugar is heat gradually, it first melts, but then begins to change colour while giving off a sweet odour, eventually turning completely black. At what exact point would you say a chemical reaction began to take place? Explain your answer.