Physical and Chemical Change Virtual Lab 15 videos_

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Indian Land High *

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Chemistry

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Nov 24, 2024

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VIRTUAL LAB: Physical and Chemical Changes Beginning Question: How do physical changes differ from chemical changes? Background Information: Matter can undergo physical and chemical changes. In a physical change, matter changes its appearance (physical properties) but not its composition. Examples of physical changes include changes of state (between solid, liquid, and gas phases) and making mixtures. On the other hand, in a chemical change, matter does change its composition (new substances are made). For example, the Statue of Liberty, which is covered with copper, turned green upon exposure to air because the copper reacts with gasses in air to form new compounds. The following are clues that indicate that a chemical change may have occurred: • unexpected color change or odor change • formation of gas (bubbles form) • formation of a precipitate (solid forms in a liquid) • energy change (change in temperature, light, sound) Task: For each “station”, click on the link and use the videos below to make observations of the changes in the video in the data table below. o INITIAL APPEARANCE: make sure to include color of substance and state of matter. o OBSERVATIONS: what do see and hear video (during and after the change) ▪ Observations include all these items: color, odor, temperature, clear or cloudy (for liquids only) ▪ Observations tell if heat, light, or electricity were added during the experiment o FINAL APPEARANCE: make sure to include color of substance and state of matter. o TYPE OF CHANGE and CLUE: is the change physical or chemical and how did you determine this. ▪ Uses the term physical or chemical change (may be both). Clues are the observations used to back up an opinion. Station # Initial appearance Observations Final appearance Type of Change & Clue Station #1: Lead Nitrate and Potassium Iodide solutions. Shower of yellow Clear liquid The yellow is dispersing throughout the clear liquid. It forms lines of yellow that fall to the bottom of the clear liquid. Then it turned a light brownish yellow. A cloudy light brownish yellow. Towards the top it was more yellow. Physical change because it changed in color and the change in color is a physical change. Station #2: Potassium Chlorate and Gummy cloudy white liquid When the gummy bear hit the potassium chlorate it cloudy mixture all over the Chemical change because it was an exothermic

bear. Gummy began a kind of rapid fire. It began to smoke. walls of the tube. reaction. Station #3: Elephant toothpaste. Elephant toothpaste a dark red liquid, a dark green liquid and light blue dawn dish soap. When the peroxide was added it caused the liquid to turn into this foam-like substance and made it expand to over 10 times its original size. It also changed from a dark green to a light blue. When done in a container with a smaller opening it reacts by shooting really high up but when done in a container with a larger opening it just spilled out the sides. Large foam-like substances. A chemical change, because a new substance with new properties are formed. Station #4: Copper and Nitric Acid. Cu + Nitric acid A regular penny. Not new, a dark brownish color. When the nitric acid is added it turns a greenish color and a gas is formed. The gas is a dark orange color. The liquid then started to bubble. After a while the liquid started to turn blue. A dark orange gas and a blue liquid. Chemical reaction because a gas is formed. Station #5: Carbon Disulfide and Nitric Oxide. Carbon Disulfide and Nitric Oxide A colorless gas. When the nitric oxide mixed with the oxygen it turned to a brownish gas called nitrogen dioxide. When the carbon disulfide is added to the nitric oxide and the light is added it makes the liquid ignite into a blue flame. Made a boom-like yellow sulfur left on the edges of the container. Chemical reaction because it forms an ignition of the mixture.

sound . Station #6: Chemiluminescence. Chemiluminescence The video wouldn't open. Station #7: Color changing milk. Milk regular milk with drops of food dye added. When the drops of food dye mix with dawn dish soap it makes the colors disperse through the milk. colorful milk physical change occured because the milk changed color. Station #8: Silver nitrate and Hydrochloric acid. Silver Nitrate and HCl clear liquid made a solid cloudy white substance solid substance that is a cloudy white color. It also floats at the top of the clear liquid. A chemical change because it made a solid from a liquid. Station #9: Ammonium Thiocyanate and Barium Hydroxide Octahydrate. Watch this! wood that had water on it when the ammonium thiocyanate is placed on the wood and mixed with barium hydroxide octahydrate it gets colder making the wood stick or freeze to the glass container. the wood froze the the class container a chemical change occurred because of the change in temperature. Station #10: Salt Crystal Garden. Salt crystals a paper towel roll when placed in the liquid it formed these salt crystals on the paper towel roll. Salt crystals formed. Chemical change occurred because a new substance was formed. Station #11: Combustion of iron in pure oxygen. Combustion a clear gas When mixed with a heated up iron coil it forms a type of fiery explosion. a cloudy white gas is formed a chemical reaction occurred because there was a change in temperature and a new

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substance was formed. Station #12: Genie in a bottle. Genie 30% hydrogen peroxide When mixed with the manganese dioxide it forms a white cloudy gas. a white cloudy gas is formed A chemical change occurs because a new substance is formed and there is a change in temperature. Station #13: Halloween clock reaction. orange and black Station #14: Fun with Sodium Acetate. Sodium Acetate clear liquid when heat is added it makes the clear liquid freeze frozen liquid a chemical change occurred because there was a change in temperature. Station #15: Cold but Sublime. Cold hot liquid When the hot liquid is put into a really cold temperature it forms a gas. a cloudy white gas is formed. chemical reaction because a new substance is formed. Post Lab 1. Define endothermic- A chemical reaction that absorbs energy in the form of heat 2. Define exothermic- A chemical reaction that releases energy in the form of heat 3. What stations had an endothermic process or reaction? How did you determine this? 14, 9, 10, 4. What stations had an exothermic process or reaction? How did you determine this? 15, 12, 2, 5, 11,