Question

during a laboratory experiment, four students each combined two substances and recorded their observations.
which student most likely produced a new chemical substance?
a. student 1
b. student 2
c. student 3
d. student 4

Explanation:

Step1: Understand chemical reaction

A new chemical substance is formed when there is a chemical reaction. A chemical reaction often shows signs like color change, gas production (bubbles), precipitate formation, etc.

Step2: Analyze each student's observation

• Student 1: Just mixing two substances (clear liquid and clear liquid at 15°C) without any sign of new substance formation like color change, gas, or precipitate.
• Student 2: Clear liquid (Substance I) and blue solid (Substance II) combine to form a clear liquid that bubbles. Bubbling can indicate gas production (a sign of chemical reaction and new substance formation).
• Student 3: White solid (Substance I) and clear liquid (Substance II) form a white solid that floats. This could be a physical change (like dissolution and floating, not necessarily a new chemical substance).
• Student 4: Yellow liquid (Substance I) and white solid (Substance II) form a white solid on top of yellow liquid. This might be a physical separation or simple mixing, not a clear sign of new chemical substance.

Answer:

B. Student 2