Does mixing two or more substances always result in the formation of new substances? Why?
Hypothesis:
Objective:
Investigate different types of mixtures to determine if new substances are formed after mixing and understand the differences between physical and chemical changes.
Materials:
Beakers or clear plastic cups (3-4 per group)
Water
Sand
Salt
Vinegar
Baking soda
Steel wool
Glass stick/rods
Spoon-spatula
Petri dish
Scale
Matchsticks
Procedures:
Introduction:
Physical changes do not result in new substances, whereas chemical changes do.
Prepare Mixtures:
Mixture 1: Mix 1 spoon of salt and 80mL of water in a beaker. Stir with the glass stick until the salt dissolves.
Mixture 2: Mix 1 spoon of sand and 80mL of water in a separate beaker. Stir with the glass stick.
Mixture 3: Mix 1 spoon of baking soda and 10mL of vinegar in a third beaker and observe.
Mixture 4: Using a scale, measure the weight of the steel wool in a petri dish. Using the matchstick, put fire in the steel wool and observe. Mesure the weight of the system again.
Results:
Observe the mixtures and write down everything you observed. Note changes such as color, temperature, gas production (bubbles), or other indicators.
Think about it: Are the substances easily separable or appear to have combined irreversibly?
Guiding Questions for Discussion:
What did you observe when you mixed the substances?
Did any of the mixtures produce bubbles, heat, or other noticeable changes?
Do you think it’s possible to separate (or reverse) all the components of the mixtures? How?
Based on your observations, which of these mixtures do you think resulted in new substances? Why?
Guiding Questions for Conclusion:
How can you tell if a new substance is formed after mixing two or more substances?
Which of the mixtures represented physical changes and which represented chemical changes? Explain your reasoning.
What are some real-life examples of mixtures that do not create new substances, and those that do?
How can this investigation help you in identifying chemical reactions in everyday life?
Was your hypothesis correct? If your answer is yes, what did you do in your experiment that confirm your answer? If not, how does the experiment answer the research question correctly?
