Page 22 - ICSE Chemistry 8
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formed are the same as the ones present in the reactants, thereby conserving the total mass. Hence, we
can say that the total mass of the reactants is equal to the total mass of the products in a chemical reac on.
Activity 1.2
Aim: To show that the total mass remains same during a physical change
Materials required: An ice cube, sealable plas c bag, measuring scale
Procedure
• Take a sealable plas c bag and keep an ice cube in it.
• Measure the mass of the ice cube and the plas c bag.
• Keep the bag aside and wait un l the ice cube melts.
• Measure the mass of the plas c bag again when the ice has melted.
• Compare the mass of the plas c bag with ice cube in it and when the ice cube has melted.
• Record your observa ons.
Observa on: You will observe that the ice cube changes its form from solid to liquid but there is no
change of mass involved.
Conclusion: Hence, it can be conclude that substances change their forms during a physical change but
the total mass remains constant.
Activity 1.3
Aim: To show that the total mass remains same during a chemical change
Materials required: 20 ml vinegar, 2 cups, a sealable plas c bag
Procedure
• Take 20 mL vinegar in a cup and measure the mass of the cup with vinegar.
• Similarly, take 10 g baking soda in another cup and keep it in a sealable plas c bag. Measure the
mass of the plas c bag containing the cup.
• Now, keep the cup containing vinegar inside the same plas c bag that consists of cup containing
baking soda.
• Carefully, without opening the seal of the bag, pour the vinegar into the cup containing baking soda.
Now, measure the mass of the sealed plas c bag.
• Record your observa ons and compare the mass of the reactants and products.
Observa on: You will observe that reactants mix together to form a product but there is no change of
mass involved.
Conclusion: Hence, it can be conclude that reactants take part in chemical reac on to form new products
but the total mass remains constant.
Total mass of reactant = Total mass of products
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