PLS HELP Conservation of Mass Activity Worksheet Instructions: Observe and analyze the interactions between the substances pictured in the slide show. Compare the properties of substances before and after each interaction. You will submit your completed worksheet for grading. Data Table On the table below, record your observations before and after the interactions and note if mass was conserved. Describe the changes in properties that prove a chemical reaction occurred. The first row is an example. Observations Before Interaction Observations After Interaction Was Mass Conserved? Proof of a Chemical Reaction Example: Sugar + Heat The sugar is in tiny white particles in a pile. Heat is not seen but is implied by the heat source. The pile of sugar in the pot weighs 100 grams. There is a solid, light brown mass at the bottom of the pot. It weighs 100 grams. Yes, both the reactants and the products weigh the same. There was not a chemical reaction. Sugar did not change composition. It only melted. Melting point is a physical property, and this is a physical change. Steel Wool + Oxygen (Fire)= Egg + Heat= Water + Heat= Zinc + Hydrogen Chloride Sodium Hydroxide + Copper Sulfate=

Steel Wool + Oxygen (Fire)  The steel wool is a grayish color and has a rough surface. Oxygen is transparent  It looks like a powder, and like if it was rusted steel wool but then broken apart and turned into a powder  Well Iron oxide is 7 grams and steel wool combined is 7 grams so you can say that the mass was conserved  Yes, this is a chemical change because the steel wool rusted and rust is a chemical change, so iron oxide is cause because if a physical change.

Egg + Heat  The egg has a yellow yolk in the middle while there is some type of liquid at the border of the yolk, but it is clear, the heat is hot but transparent  The egg turned into a delicious food called an omelet what was yolk staid as a liquid but got a tad harder, but the transparent border around it turned white  It was conserved because the eggshell was 4 grams and the fried egg is 41 grams  It is a chemical change because it results in the formation of new particles, and the chemical bonds break up and new ones are formed.

Water + Heat  The water is a clear liquid, while the heat is very hot but transparent  The water turned into a type of oxygen -Water Vapor-   If 5 g of water becomes a gas it becomes 5 g of water vapor. The mass of the liquid water is simply transferred into the mass of the newly formed water vapor.  There was no chemical reaction because the water vapor can be turned back to water also it just changed from a liquid to a gas and did not change its composition  

Zinc + Hydrogen Chloride  Zinc: a white/silver metallic solid. Hydrogen chloride (dilute hydroelectric acid) a transparent, colorless liquid with a very low pH (acidic). Zinc "dissolved" in hydrogen chloride, while emitting a colorless gas.  The liquid remains a colorless liquid, possibly still having a low pH from the unused acid. The colorless gas collected in a test tube gives a popping sound when ignited with a burning wooden splint, so it is not air embedded in the zinc, nor dissolved in hydroelectric acid.  Well although the zinc chloride is 12 grams and not 15 the gas that was released was 3 grams and as we all know 3 + 12 is 15 so you could say that the mass was conserved The production of a new substance (most probably hydrogen) from the reaction of the two reactants. When a few drops of the liquid product are evaporated on a watch glass, a white residue is left.

When a few drops of the liquid hydroelectric acid are evaporated on a watch glass, there is no residue. This proves that a new product (hydrogen gas), (white powder, zinc chloride) is produced instead of zinc being physically dissolved in hydroelectric acid.

Sodium Hydroxide + Copper Sulfate  Sodium hydroxide is a turbid solution and copper sulfate is in form of bright blue crystals. When their solutions are mixed with each other, a pale blue precipitate of basic copper hydroxide & a solution of neutral salt sodium sulfate will be formed. The sodium hydroxide and the copper sulfate combined make a total of 67 grams and the product  is split because the sodium sulfate is 47 grams and the copper hydroxide is 20 grams but all together it is still 67 grams so you could say that the mass was conserved The proof of the reaction is the appearance of pale blue precipitates of basic copper hydroxide & a solution of neutral salt sodium sulfate.

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