Question

nicole has 2 glasses on the counter: one of water and one of sugar - water. she is baking a cake and needs to use the sugar - water for the glaze. both glasses look identical, but one contains a mixture and the other contains a compound
is sugar - water a mixture or a compound? define mixtures and compounds, and explain how, without tasting it, nicole can test to make sure she is using the sugar - water in the glaze.

Explanation:

1. Definition of Mixture and Compound:

• A mixture is a combination of two or more substances that are physically combined and can be separated by physical means. The substances in a mixture retain their individual chemical properties. For example, in a mixture of sand and salt, we can separate them using methods like filtration (to separate sand) and then evaporation (to get salt from the salt - water filtrate).
• A compound is a substance made up of two or more different elements that are chemically bonded together in a fixed ratio. The elements in a compound lose their individual properties and form a new substance with unique properties. For example, water ($H_2O$) is a compound where hydrogen and oxygen are chemically bonded in a 2:1 ratio, and it has properties different from both hydrogen and oxygen.

1. Why Sugar - water is a Mixture:

• Sugar - water is a mixture because sugar (sucrose, $C_{12}H_{22}O_{11}$) and water ($H_2O$) are physically mixed. The sugar can be separated from the water by physical processes like evaporation. When we evaporate the water from the sugar - water solution, the sugar will be left behind, and the water can be collected as vapor and then condensed back to liquid water.

1. Testing Method for Nicole:

• Nicole can perform an evaporation test. She can take a small amount of the liquid from each glass and place it in a clean, dry container (like a watch glass). Then, she can gently heat the container. If the liquid is sugar - water (the mixture), upon heating, the water will evaporate, and she will be left with solid sugar crystals. If the liquid is pure water (the compound, $H_2O$), upon heating, all the liquid will evaporate, and there will be no solid residue left. This way, without tasting, she can identify which glass contains the sugar - water (the mixture) to use for the glaze.

Answer:

Sugar - water is a mixture.