Question

A student was given two clear liquids; a colorless liquid and a dark-blue liquid. The student was asked to combine the liquids in a beaker and record observations. Which of the following results, if true, would provide the best evidence that a chemical change took place when the liquids were combined?
a) The resulting mixture was cloudy.
b) The total volume of the mixture was equal to the sum of the initial volumes.
c) The resulting liquid was light blue.
d) The liquids formed two separate layers in the beaker.

Answer 1

Answer:

The correct option is;

a) The resulting mixture was cloudy

Explanation:

Here we have the initial color as

1. Colorless and

2. Dark blue

We analyze each of the results as follows

a) The resulting mixture was cloudy

A cloudy mixture forming when the two liquids are mixed is most likely due to the formation of a suspension from  a new substance That is a new compound is formed

b) The total volume of the mixture was equal to the sum of the initial volumes.

Here since there is no change in the physical properties as the volume of the mixture is the sum of the volumes of the  constituent then there is unlikely to be a chemical change

c) The resulting liquid was light blue

Here, the observation is more of a physical change

d) The liquids formed two separate layers in the beaker.

This is an indication that there was no mixing of the liquids hence no reaction or chemical change.