Understanding Elements, Compounds, and Mixtures: A Study Guide
School
Rancho Buena Vista High**We aren't endorsed by this school
Course
CHE 120A
Subject
Chemistry
Date
Dec 12, 2024
Pages
1
Uploaded by CommodoreRose3807
GUIDE: Group Exercise #1 1. Which of the following are elements? Which are compounds? Explain your reasoning. Mg, Al, Cl, are elements because they consist of one type of particle. CO,, Na(Cl are compounds because they consist of two or more types of particles. 2. Draw particulate-level representations of two molecules, hydrogen and water. Are these molecules elements or compounds? Explain your reasoning. Hydrogen 1s an element, water 1s a compound. Same reasons as above. ® & 3. Classify the following as homogeneous or heterogeneous. Explain your reasoning. cola (freshly opened versus days old) — freshly opened 1s heterogeneous (has gas bubbles), days old will likely appear homogeneous. air (1n this room versus over LA) — homogeneous 1s this room, on most days air looks heterogeneous over LA (heavy particulate matter —smog!) sand (1n an hour glass versus on the beach) in an hour glass 1s likely homogeneous (usually a clean sand), on the beach 1s better descrnibed as hetvwgeniow (bits of shells, etc.) glass (clear versus stained) — clear glass usually looks homogeneous, stained glass could be either, but some stained glass has bubbles 1n the glass so would be heterogeneous 4. Classify the following as a pure substance or a mixture. Explain your reasoning. water (bottled water versus sea water) — both are mixtures (bottled water still has dissolved substances in 1t — check the label) because they have more than one type of matter table salt — pure substance (e.g., just NaCl — one type of matter) or mixture (NaCl and KCl - more than one type of matter); also note that table salt does have small amounts of ‘contamunants’, so would be best described as a mixture ammonia (NH;, substance in window cleaner) - pure substance (if just NH; — has one type of matter), or a mixture (1f you are descnibing the solution of glass cleaner, which contains water, NH; and other compounds) bromine (Br,) gas — pure substance — has one type of matter 5. Give an example of a homogeneous pure substance, a homogeneous mixture, a heterogeneous pure substance, and a heterogeneous mixture. homogeneous pure substance — liquid mercury, solid 1ron (no rust) homogeneous mixture — salt dissolved in water heterogeneous pure substance — water 1ce cubes 1n liquid water (assume pure water) heterogeneous mixture — sand and water
