A student takes four samples of a white crystalline solid and places each in a well plate. On top of each sample, she carefully places 20 drops of clear mystery liquids A, B, C and D. Her results for each well are as follows: Liquid A: The solid dissolves quickly.

Liquid B: The solid appears unchanged.

Liquid C: A brownish colored liquid is produced.

Liquid D: Fizzing occurs and the well becomes warmer.

In which well does a PHYSICAL change occur?

Liquid B: The solid appears unchanged.

Explanation:

A is a chemical change, because the solid dissolves away.

C is a chemical change, because the solid changes color.

D is a chemical change, because fizzing occurs.

B is the only solid that seems to remain the same.

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.