Chemical Reaction Indicators: Change in Size
A chemical reaction signifies the formation of new substances with distinct properties. While certain observations strongly suggest a reaction has occurred, others do not reliably indicate it.
Evidence of Chemical Reactions
The following are common indicators that a chemical reaction might be happening:
- Change in colour: Often signifies the creation of new chemical compounds. For instance, metal rusting changes its colour.
- Evolution of a gas: Vigorous bubbling or fizzing points to the production of a gas, a frequent outcome of chemical changes.
- Change in state: Although state changes like melting are physical, a chemical reaction can result in a substance changing its state, for example, producing gases from solid reactants.
Evaluating Change in Size
A change in size, whether an increase or decrease, is typically characteristic of a physical change, not a chemical reaction. Examples include:
- Materials expanding or contracting due to temperature changes.
- Objects physically breaking down or eroding over time.
Because a change in size does not necessarily involve the formation of new chemical substances, it does not serve as a definitive indicator that a chemical reaction has taken place. The other options listed are more direct indicators of chemical change.
Similar Questions
- What is oxidization?
- With which substance does silver react and turn black?
- Which chemical process results in the formation of plaque on copper, the rusting of iron and the blackening of silver?
When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium hydroxide. This process is called:
When Barium Chloride (BaCl2) solution is mixed with Sodium Sulfate (Na2SO4) solution, a white product Barium Sulfate (BaSO4) is formed. This product is known as a ______.
Which of the following statements about carbon monoxide in the air is correct?
During an experiment, iron nails are placed in copper sulphate solution, and a reddish-brown deposit forms on the nails. What does this observation demonstrate about the type of chemical reaction and the substances involved?
When dilute Hydrochloric acid (HCl) reacts with Sodium Hydrogen Carbonate (NaHCO3), which is the product formed along with Sodium chloride (NaCl) and Water (H2O)?
Which metal reacts violently with cold water, producing a metal hydroxide, hydrogen gas, and enough heat for the hydrogen to catch fire?
In the reaction Na2SO4(aq) + BaCl2(aq) → BaSO4(*) + 2NaCl(aq), what will be the actual physical state that can replace (*)?
Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which is the most reactive metal?
